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Alternative Water Resources Cluster

Alternative Water Resources: A Review of Concepts, Solutions and Experiences



International Water Association

2015

AlteRnAtive WAteR ResouRCes: A RevieW of ConCepts, solutions

And expeRienCes

Main authorsDevon Hardy

Francisco Cubillo

Mooyoung Han

Hong Li

Key Contributors And ReviewersHelena Alegre

Bambos Charalambous

Israel García

Raül Glotzbach

Jan Hofman

Valentina Lazarova

Walter Malacrida

Patricia Gómez Martínez

Tim Waldron

Xiaochang Wang

PREFACEEvery resource used to supply water demand in an urban zone could be considered as alternative. Historically, since

settlements were located some distance from water sources, a variety of sources and technologies for abstraction,

conveyance, treatment and waste collection were emerging. Population growth and evolving enabling technologies led to

new forms of alternative resources that were able to satisfy needs and specific requirements for water related activities. At

the beginning, solutions were mainly focused on looking for additional reliable and good quality raw water resources without

considering that large infrastructures were required to abstract, store and convey water to consumption points. Since cities

and water demands were growing, potential solutions became more expensive, with high marginal costs and significant

environmental impact. In some cases these solutions were just unfeasible or created considerable social reluctance.

All over the world, the search for affordable, acceptable and reliable solutions is today a common challenge for water

supply planners. Therefore, having a sufficient quantity of water with appropriate quality is a common aim.

In this context, the water sector has been coping with different concerns throughout time. This way, finding average

demand/resources balance was the first concern, especially for water-stressed areas. Then, reliability of available resources

under droughts or scarcity scenarios became the key issue to cope with climate variability. Appropriate water quality for

health protection and to fulfil specific requirements of every use was the following challenge. Thus, technology has been

providing solutions to every problem, contextualised with different costs, impacts and consequences. Nowadays, some

solutions such as desalination, reuse, greywater, artificial recharge or rain harvesting could be considered almost as

conventional solutions as abstraction from pure streams or aquifers was long ago. There are many examples of use of those

resources and their enabling technologies.

Additionally, demand management is the other component of resources/demand balance, and, in consequence, its

contribution should be also analysed. If demand is considered as the total water that outflows from a water supply system,

demand management must include policies to reduce both the global consumption and the different types of real loss.

Every context and city has a variety of options with different figures of marginal costs, (economic, social and

environmental) and with different reliability for the availability/demand balance.

A review of the mentioned alternative options that focus on resources and demand has been compiled and described in

detail in this Compendium. Likewise, case studies and parameters to assess their costs and benefits are described.

This Compendium is a good starting point for the activities planned in IWA’s Alternative Water Resources Cluster. There

are many identified ways to move forward within the cluster: new solutions for appropriate water balance, such as water

trading, cloud stimulation, and applications of other smart technologies, new methods to assess reliability and to include risk

parameters and principles, new criteria to compare in a consistent way potential options with all their significant parameters

such as environmental impact, sustainability or social preferences. Perhaps at the end of this process we strongly

acknowledge that we are not dealing with just alternative resources, but we will be dealing with reliable and resilient supply

systems. Resources will probably be as alternative as they were in the past but solutions will be linked to energy, resilience

and sustainability in a new comprehensive and efficient approach.

■ FRANCISCo CubILLo

AbbreviationsA2O Anaerobic–Anoxic–OxicASR Aquifer Storage and RecoveryAWR Alternative Water ResourcesBOD Biological Oxygen DemandCBA Cost-Benefit AnalysisCOD Chemical Oxygen DemandCSP Concentrated Solar PowerCSR Corporate Social Responsibility CSU Colorado Springs UtilitiesCW Constructed WetlandDMA District Metered AreaDPR Direct Potable ReuseED ElectrodialysisEIA Environmental Impact AssessmentESB Engineered Storage BufferFESR Fuel Energy Savings RatioFO Forward OsmosisGL GigalitreGPT Gross Pollutant TrapGRP Goreangab Reclamation PlantGWF Gippsland Water FactoryHKIA Hong Kong International AirportHSFW Horizontal Subsurface Flow WetlandIC Internal CirculationICI Institutional, Residential and IndustrialILI Infrastructure Leakage IndexIMS Integrated Membrane SystemIPR Indirect Potable ReuseIWA International Water AssociationIWRM Integrated Water Resources ManagementKDWS Korean Drinking Water StandardKGWS Korean Gray Water StandardkWh Kilowatt HourLBSE Lithium Bromide-water Simple EffectLCA Life-Cycle AnalysisLID Low-Impact DevelopmentMBR Membrane Bioreactor

MD Membrane DistillationMED Multiple-Effect DistillationMEH Multi-Effect HumidificationMENA Middle East and North AfricaMF Microfiltrationmg/L Milligrams per LitreMm MegametreMNF Minimum Night FlowMSF Multi-Stage FlashMVC Mechanical Vapour-CompressionMWh Megawatt HourNAD Natural Aeration DitchNF NanofiltrationNRW Non-Revenue WaterNWD No Water DayORC Organic Rankine CyclePLP Peak-Load PricingPSDP Perth Seawater Desalination PlantPV PhotovoltaicRO Reverse OsmosisROS Regional Outfall SystemRW RainwaterRWH Rainwater HarvestingSDG Sustainable Development GoalSNU Seoul National UniversitySODIS Solar DisinfectionSW StormwaterTDS Total Dissolved Solids TSS Total Suspended SolidsTWS Triple Water SupplyUASB Upflow Anaerobic Sludge BioreactorUF UltrafiltrationUV UltravioletVBFW Vertical-Baffled Flow WetlandVMD Vacuum Membrane DistillationWUE Water Use EfficiencyWWTP Wastewater Treatment Plant

Contents1 INTRODUCTION 1

1.1 Overview Of Challenges 1

1.1.1 Water Quantity 1

1.1.2 Water Quality 2

1.1.3 Energy and Climate 3

1.2 Drivers Of awr Use 3

1.3 ratiOnale 4

1.4 sCOpe anD ObjeCtives 4

2 RaINwaTeRHaRvesTINgaND

sTORmwaTeRCOlleCTION/maNagemeNT 5

2.1 rainwater harvesting 5

2.1.1 Unlocking the Potential of Rainwater Harvesting 5

2.1.2 Tackling Rainwater Shortage in Dry Seasons 7

2.1.3 Challenges and Considerations in Rwh

Implementation 7

2.1.4 Future of Rainwater Harvesting 8

2.2 stOrmwater COlleCtiOn anD management 9

2.3 infiltratiOn anD green rOOfs 9

3 waTeRReUseaNDDesalINaTION 11

3.1 water reUse 11

3.1.1 Potable Water Reuse 11

3.1.2 Non-Potable Reuse 13

3.1.3 Greywater Reuse 14

3.2 DesalinatiOn anD saline water Use 15

3.2.1 Reverse Osmosis (Ro) 16

3.2.2 Other Non-Thermal Desalination 16

3.2.3 Thermal Desalination 17

3.2.4 Saline Water Use 18

3.2.5 Development on Low-Energy Desalination 18

4 DemaNDmaNagemeNTaNDwaTeRlOss

ReDUCTION 20

4.1 eCOnOmiC inCentives 20

4.2 water-saving teChnOlOgies 22

4.3 water lOss reDUCtiOn 23

4.4 OperatiOnal effiCienCy 27

4.5 eDUCatiOn anD awareness 27

4.6 COmbineD DemanD management sOlUtiOns 28

5 TOwaRDsRelIableaNDsUsTaINable

waTeRsUpplysysTems 30

5.1 COnsiDeratiOns anD examples 30

5.2 inflUenCing faCtOrs in water sUpply systems 33

5.2.1 Environmental Factors 33

5.2.2 Social Factors 33

5.2.3 Economic Factors 33

5.2.4 Political/Institutional Factors 34

6 sHOwCaseOfawRTeCHNOlOgy 35

6.1 hOng KOng internatiOnal airpOrt 35

6.2 perth, aUstralia: rO DesalinatiOn 36

6.3 hybriD COnstrUCteD wetlanDs, China 38

6.4 maDhya praDesh, inDia 39

6.5 tenOriO wastewater treatment plant, mexiCO 40

6.6 gOreangab reClamatiOn plant, winDhOeK,

namibia 41

6.7 gUelph, CanaDa 41

6.8 bOra bOra, frenCh pOlynesia 42

6.9 KOgarah, syDney, aUstralia 43

6.10 star City, seOUl, sOUth KOrea 44

6.11 DeCentraliseD water reUse with

ZerO DisCharge, China 45

6.12 sChOOl DrinKing water sUpply in hanOi,

vietnam 46

7 KNOwleDgeaNDTeCHNOlOgygaps 48

7.1 Data COlleCtiOn anD integratiOn 48

7.2 framewOrK fOr assessing Case-by-Case

sCenariOs On the basis Of envirOnmental impaCt

anD COst-effeCtiveness 48

7.3 mOre effeCtive anD reliable water sOlUtiOns

fOr ariD Climates 48

7.4 high rates Of water lOss 49

7.5 laCK Of pUbliC aCCeptanCe Of reClaimeD

water 49

7.6 safety anD sUstainability in transpOrtatiOn 49

8 ReCOmmeNDaTIONs 50

8.1 awr visibility 50

8.2 teChnOlOgiCal aDvanCement 50

8.3 framewOrK fOr awr assessment 50

8.4 system reCOnfigUratiOn 51

8.5 fit-fOr-pUrpOse treatment anD UtilisatiOn 51

8.6 DynamiC strategies 52

8.7 envirOnmental priOrities 52

9 CONClUsIONs 54

10 RefeReNCes 55

01 IWAALTERNATIVEWATERRESOURCESCLUSTER

1 introductionWateravailabilityisanissueofincreasingglobalconcern.Asusagecontinuestoexceedsustainableratesandgreater

quantitiesofpollutantscomeincontactwithoncepristinewatersources,morepeoplearebecomingconcernedasto

wheretheirwaterwillcomefrom.Anaverageof3.3millionpeoplediefromwater-relatedillnesseseachyearand,in2008,

46%ofpeopleonEarthlivedinhomeswithoutpipedwater(Macedonioet al.,2012).Ifcurrentconsumptiontrends

continue,two-thirdsoftheglobalpopulationwillbelivingwithseverewaterscarcityby2025(Macedonioet al.,2012).

AccordingtotheUnitedNationsWorldWaterDevelopmentReport(UNWater,2015b),demandforwaterisexpectedto

increaseinallsectorsofproductionand,by2030,theworldisprojectedtofacea40%globalwaterdeficitunderthe

business-as-usualscenario.Inadditiontothis,climatechangeisincreasingthefrequencyandintensitybothofdroughtsand

ofstormevents,whilehigherairtemperaturesnecessitategreaterwateruseforcropirrigationandlivestock.Forthese

reasons,alternativewaterresources(AWRs),suchasrainwaterharvest(RWH),waterreuseanddesalination,aswellas

movingtowardsmoreholistic,integratedapproachestowatermanagementarebecomingmorepopularformeetingthe

globalwaterneedsthatmaynotbesatisfiedbyasinglewatersource.

1.1 OVERVIEW OF CHALLENGES

Inthefieldofwaterresourcesmanagement,wearecurrentlyfacingchallengesrelatingbothtothequantityandthequality

ofwatersources.Challengesarediverseintheircausesandeffects,butmustbeconsideredtoensuregreatersustainability

inthewatersector.

1.1.1 WATER QUANTITY

1.1.1.1 Resource Depletion

Notonlyistheglobalpopulationincreasingatanexponentialrate,buteconomicdevelopment,urbanisationand

globalisationhaveresultedintheaveragepersonhavinghigherconsumptionpatternsandweakerconnectionstothe

originoftheirconsumedresources.Meat-heavydietsareontherise,increasingresourceconsumption,andanincreasing

proportionoftheglobalpopulationisconcentratinginmegacities,disproportionatelystrainingresourcesinthoseareas

(ButlerandMemon,2006).Onanevenlargerscale,theamountofwaterneededtoirrigateagriculture(whichcomprises

over70%oftheworld’sfreshwateruse(FoodandAgricultureOrganizationoftheUnitedNations,2013))hashadto

increasetofeedthegrowingpopulation,andascountriesstrivetodeveloptheireconomies,waterneedsinindustrial

sectorshaveincreasedaswell.Thisdemandhastypicallybeenmetbyincreasingtheextractionrateoffreshwaterfrom

surfacewaterbodiesandundergroundaquifers,which–ifitexceedstherateofreplenishment–leadstodepletionof

theresource,andcanpossiblycauselandsubsidenceifgroundwaterisover-extracted.Conventionalwaterresourcesare

nolongersufficienttomeetdemand.AccordingtoNget al.(2013),globalwaterdemandisprojectedtoincreaseatan

averageannualrateof2%,leadingtoademandofcloseto7trillionm3bytheyear2030,asisillustratedinFigure1.1.

Giventhatwaterscarcityisagrowingthreatworldwide,thisrisingdemandislikelytohavedetrimentaleffectsontheglobal

populationanditswaterresourcesifitisnotaddressed.

1.1.1.2 Climate Change and Drought

Climatemodelspredictthatthetrendofincreasingglobalwaterscarcitywillcontinueasclimatechangeimpactsbecome

moresevere.Withthesechanges,precipitationpatternsbecomemoreerratic,evaporationandtranspirationratesrisewith

increasedairtemperaturesandwaterresourcesthereforebecomemorescarceandlessreliable(Olsson,2012).Allover

theworld,particularlyinaridclimates,lakesareshrinkingdramaticallyordisappearingcompletely,affectingbothecosystems

andhumanuse(Liuet al.,2013).Stern(2007)predictsthatjusta2°Cincreaseinaverageglobaltemperaturecouldresult

inbetween1billionand4billionpeople–particularlythoseindevelopingcountries–becomingvictimsofseverewater

scarcity.Someofthewater-relatedimpactsofclimatechangeincludediminishingfreshwatersuppliesduetoshrinking

glaciers,decreasedprecipitationandincreaseddroughtpropensity,higherfrequencyofflooddisastersinsomeareasdue

toseverestormeventsandunreliablesuppliesofbothfoodandwater(Morrisonet al.,2009;Olsson,2012).Theseissues


willprobablybecomeexacerbatedashigheratmospherictemperaturesdrivetheneedforincreasedwateruseinagriculture

andlivestockproduction,freshwaterresourcesbecomecontaminatedbecauseofseawaterinfiltrationandpollutant

discharge,andprecipitationpatternsbecomelesspredictable.Ifenergydemandandcarbonemissionsarenotreduced,all

ofthedetrimentaleffectsofclimatechangearelikelytoincreasemorequickly.Therefore,amoreresilientwatersupplyis

needed,asistheproliferationofmoreenergy-neutralpracticeswithinthewatersectortohelpmitigateclimatechange.

1.1.2 WATER QUALITY

1.1.2.1 Risks to Human Health

Thedischargeofwastewaterbackintowaterbodies,dumpingofindustrialchemicalsintothosesamesourcesand

excessiverunoffofstormwateroverpollutedareashaveresultedinthecontaminationofgroundwaterandsurfacewaterthat

wasonceorstillisusedfordrinking.Inmanyareas,contaminantscanbeeffectivelyremovedwithtreatmenttechnology.

However,someregionseitherlackthecapacitytotreattheirwatertopotablestandardsorthecontaminantspresentin

thesupply–suchasheavymetals,pesticidesandevenpharmaceuticalcompounds–cannotberemovedbycurrently

implementedtechnologies.Bangladeshisaprominentexampleofacountrystrugglingtomeetdemandforfreshwater

becauseofsourcecontamination.Arseniccontaminationinaquifershasledtoepidemicratesofcancerandotherdiseases,

withanestimated30millionpeopleexposedtoarsenicinconcentrationsgreaterthan50μg/L.Ontopofthis,muchofthe

country’ssurfacewaterhashighturbidityandsalinity,makingitunfitfordrinkingandnecessitatinganalternativesourceof

clean,reliableandaccessiblepotablewater(Karim,2010a).However,Bangladeshisnottheonlycountrysufferingfrom

theseissues;Pimentelet al.(2004)statethat,indevelopingcountries,90%ofallinfectiousdiseasesarespreadthrough

orrelatedtowater.Pollutioninwatersourcesconstrainstheuseoftheseresources,andpropertreatmenttechnologyor

alternativesourcesofwaterareneededtoovercomethisissue.

1.1.2.2 Ecological Health

Theexcessivewithdrawalofwaterfromrivers,lakesandaquiferscanbeverydisruptivetoaquaticandsurrounding

terrestrialecosystems.McKayandKing(2006)statethatecosystemsarehighlysensitivetothealterationofhydrological

flows,whichoccurswhenwaterisextractedfromriverinesystems.Reducingdepthandstream-wettedareamayalteror

destroythehabitatofcertainorganismsanddecreasebiodiversityintheecosystem.Itcanalsoreducedissolvedoxygen

concentrations,whichcanbedetrimentaltoaquaticorganisms.Inadditiontothis,thedischargeofpoorlytreated

wastewaterorsalinebrineintonaturalbodiesofwatercancauseharmtoaquaticecosystems,especiallywithcontinual

introduction.Compoundingthisissuefurther,thereducedvolumeofavailablewatercausedbyover-extractionconcentrates

thesecontaminantsbecausedispersionislimited.Finally,urbanisationoftenresultsintheremovalofvegetationandriparian

buffers,leadingtofurthercontaminationfromurbanandagriculturalrunoff.

Figure 1.1 Global water demand in 2010 compared with projected global water demand in 2030 (Ng et al., 2013).


1.1.3 ENERGY AND CLIMATE

1.1.3.1 Water–Energy Nexus

Waterandenergyareinherentlylinked.Waterisgenerallyneededtoproduceenergy(Mekonnenet al.,2015),and

energyisneededtopump,treatanddistributewater.Thisrelationshipincreasesthecomplexityofbothwaterandenergy

management.Hydraulicfracturingfornaturalgas,oilsandsdevelopmentandthermalenergygenerationareallimportant

sourcesofenergyneededtopowerindustriesaroundtheworld.However,bothoftheseprocessesrequirelargequantities

ofwater,which–ifreturnedtothenaturalenvironment–aredischargedwithsignificantlydiminishedquality.Ontheother

hand,waterscarcityisbeingaddressedthroughtheincreasingimplementationofreuse,desalinationandmoreeffective

treatmentprocesses,whicharegenerallyveryenergyintensive,thustheexistenceofthewater–energynexus.

IntheUnitedStates,thelargestwithdrawalofwaterisforevaporativecoolinginpowergenerationplants,andthelargest

consumptiveuseofwaterisagriculturalirrigation,muchofwhichgoestowardtheproductionoffeedstockforbiofuels.

Increasingly,reclaimedwaterisbeingsubstitutedforpotablewaterintheseendusestoconserveexistingfreshwaterstores,

andthereismuchcurrentresearchfocusingonrecoveringresourcestocreatemoresustainablewaterandenergysupplies.

Cleanwater,aswellasnutrientsandenergy,canberecoveredfromwastewater,andwithtechnologicalinnovationthese

processeswillprobablybecomemoreefficient.However,eveninprocessesinwhichrenewableenergyisused,water

usecanbehigh,andmanywater-efficientprocessesstillrequireagreatdealofenergy.Forthisreason,therelationship

betweenthesetworesourcesisavitalconsiderationinallwaterand/orenergy-relateddecision-makingprocesses

(Schnoor,2011).

1.1.3.2 Non-Sustainable Water-Supply

Manymethodsofacquiring,treatinganddistributingwaterarepoweredbyfossilfuels,whichexistinfinitesupplyandtend

toincreaseinpriceastheybecomescarcer.Excessiveenergyusealsocontributesgreenhousegasestotheatmosphere,

worseningtheimpactsofclimatechange.Therefore,dependenceonthesesourcestomaintainwatersupplysystemsisnot

sustainableinthelongterm(Brown,2013).Utilisingrenewablesourcesofenergysuchaswind,solarorgeothermalcan

helptoalleviatetheseproblems,buttheyoftenrequirelargecapitalexpenditures.Therefore,ifproperinfrastructureisnotin

placeandsufficientfundsarenotavailable,theirimplementationmaynotbefeasible(Gudeet al.,2010).

Anotherunsustainableaspectofpresentwatersupplynetworksistheneedtotransportwaterlongdistancesfromsource

tosuppliertoenduser.Mostmunicipalwatersuppliersarehighlycentralised,andthereforerequireagreatdealofenergy

andpipinginfrastructuretosupplywatertousers.Centralisationcanalsoresultinmorewaterlossasthereismore

potentialforleaksandinefficienciesinthesystem.Adecentralisedwatersupplythattreatsanddistributeswaterlocallyisa

moresustainableoption,andthereforeashifttothiskindofstructuremaybenecessary.

1.2 DRIVERS OF AWR USE

TheOrganisationforEconomicCooperationandDevelopment(OrganisationforEconomicCooperationandDevelopment,

2010)groupsthedriversfortheuseofAWRintofourcategories:socio-economicchanges,technologicalchange,

environmental/externalstressandpoliticalchange.

Socio-economicchangesincludepopulationgrowth,demographicchangesresultingindemandforbetterormore

environmentallyfriendlywaterprovision,expansionofurbanareasandshiftsinactivityfrompublictoprivatesectorsorvice

versa(OrganisationforEconomicCooperationandDevelopment,2010).

TechnologicalchangedrivestheuseofAWRbecauseitoftenmakesnewoptionsavailablewhicharesafer,cleaner

andpossiblycheaperthanexistingstructures.Newtechniquesthatimprovetheresourceefficiencyofwatertreatment/

distribution,simplifyprocesses,enhanceecosystemservices,createmoredurablesystemsandreducepollutionhavethe

tendencytomitigatecostsinwatersectoroperations,bothintheshortandlongterms.However,thisisnotalwaysthecase

(OrganisationforEconomicCooperationandDevelopment,2010).

Environmentalandotherexternalstressesonwaterresourcesarebecomingmorecommonwithhabitualover-extraction,

andclimatechangeislikelytoworsenthissituationinmanyplaces.Manyjurisdictionalareasarerespondingtothis

increasingscarcitywiththeintroductionofwaterreuse,desalination,demandmanagement,etc.Insomecases,itmay

notbeachoice,butanecessitytomeetstheneedsofthepopulation(OrganisationforEconomicCooperationand

Development,2010).


Politicalchanges,particularlyregulatorychanges,aremajordriversofAWRimplementation.Includedunderthiscategory

arelandusechanges,waterqualityregulations,effectivenessofgovernanceandrevenuecollection(Organisationfor

EconomicCooperationandDevelopment,2010).

Withinallofthesecategories,costbecomesamainfactoraswell.Lowercostsofrelevanttechnologiesgenerally

increaseuptakeofthesemethods(OrganisationforEconomicCooperationandDevelopment,2010),althoughforward-

thinkingwatermanagersmaymakedecisionsbasedonlong-termcostsaswell.Forexample,ahigher-costtechnologythat

causesminimalenvironmentaldamageislikelytoinducelowermitigationorrestorationcostsinthefuture,andtherefore

maybefavoured.

1.3 RATIONALE

Theexistenceoftheabovechallengesnecessitatesamoresustainableapproachtowatermanagement,onethatdoesnot

relyonasinglesourceofwatertomeetallofanarea’sneeds.Therefore,itisimportanttohaveinformationoftheAWR

optionsavailableandwaysinwhichtheycanbeusedtocreateresiliencewithinalargersystem.ThisCompendiumhas

beencreatedtoreviewalternativeoptionsfocusedonresourcesanddemand,usingevidencefromscientificpapersand

realcasestudiestoassesstheircostsandbenefits.Currentandfuturechallengestowatersuppliesarealsoaddressed,

andrecommendationsaremadeforhowtoeffectivelyandsustainablyintegrateAWRforthecreationofamorereliable

system.

1.4 SCOPE AND OBJECTIVES

WithinthescopeofthisCompendium,allpotentialwaterresources,includingsurfacewaterandgroundwaterwillbe

consideredasAWR.However,owingtoincreasingstrainonexistingsources,morefocuswillbeputonlessconventional

resourcessuchasRWH,reuseanddesalination.Theuseoftheseresourceswillbeconsideredaswaysbothtoaugment

thedrinkingwatersupplyandtocreatemoresecurewatersuppliesforagriculture,industryandotherend-usersofnon-

potablewater.

Withthecompletionofanextensiveliteraturereview,bestpracticeswillbeidentified,alongwiththeiradvantages,

disadvantagesandexamplesofhowtheycanbeintegratedintoasustainablewaterportfolio.Thesolutionsdiscussedwill

rangeintheirapplicabilityfromruraltourbansystemsandfromlow-tohigh-incomecountries.Casestudiesthat

successfullydemonstratethecreationofmorereliablewatersupplieswillbehighlightedtoshowtheviabilityofsuch

projectsandtoinspirenewprojectsofequalintegrity.Thiswillalsohelptoenabletheidentificationofgapsinknowledge

andtechnologythatmustbeaddressed.

Thedocumentaimstocoverawidespatialscale,withexamplesfromeachmajorgeographicareaandarangeof

socio-economicconditions.Thefeasibilityandapplicabilityofdifferentoptionsforenhancingtheresilienceofwatersupplies

varydrasticallybylocation.Eachcountryhasdifferentneedsandresourceavailability,aswellasuniquepoliticalclimates

andeconomiccapabilities.Therefore,attentionwillbedrawntotheseissueswhendiscussingAWR.

ExpertsinrelevanttopicshavecontributedknowledgeaboutthefuturedirectionofAWRuse,andthisinformationis

summarisedattheendoftheCompendium.Finally,asetofrecommendationsaremadeforhowtoeffectivelyand

sustainablyintegrateAWRforthecreationofamorereliablesystem.

TheobjectivesofthisCompendiumincludethefollowing.

• RaisingawarenesswithinthewatersectoroftheapplicabilityofAWRuse.

• Highlightingkeyissuesthatareaffectedordrivenbynon-sustainableresourceuse.

• CompilingandsummarisinginformationonAWRbestpracticestomakeitaccessibletointerestedparties.

• ShowcasingsuccessfulcasestudiestodemonstratedifferentapplicationsofAWR.

• IdentifyingkeytechnologyandknowledgegapsthatexistwithinAWR-relatedsectors.

• Providingrecommendationsfordecision-makersandwaterprofessionalstosuccessfullyimplementAWRsintolarger

managementplans.

• Creatingabasisonwhichprofessionalsandacademicscancollaboratetoshareknowledgeanddevelopsolutions.


2 RAINWATER HARVESTING AND STORMWATER COLLECTION/MANAGEMENTRainwaterandstormwaterareseenaspromisingAWRbecauseoftheirlowtreatmentneedsrelativetootherAWR,minimal

environmentalimpactandaddedbenefitsofrunoffandpeakflowreduction.TheapplicationofRWHdatesbacktoaround

2000bc,whereitwasusedinIsrael,partsofAfricaandIndia(Fewkes,2006).Thislonghistoryofusehasresultedin

manycivilisationsbecomingquiteefficientatusingRWHprocesses,evenwithoutthehelpofadvancedtechnology.Itis

alsoasourceofwaterwithminimalpotentialtocreateconflict,astransboundaryandpropertyrightsissuesareunlikely.

However,problemsarisinginrecentyears–suchasthepresenceofemergingcontaminants,rapidpopulationgrowthand

climatechange–haveintroducednewchallengesforRWHthatmustbeaddressedinsystemdesign.

DespitethepotentialofRWH,itspromotionislimited,probablybecauseofmisunderstandingofrainwaterqualityand

unreliablewatersupplyduetoseasonalvariation.However,goodexamplesofRWHexistandscientificinnovationis

narrowingthegapbetweenourcurrentknowledgeandfutureneeds.Whenmorethanonepurposecanbeservedatthe

sametime–suchasfloodmitigation,watersupplyandcontingencyplanning–orwhenrainwaterisusedtosupplement

theexistingwatersupply,theadoptionofRWHispromising.Inallcases,sustainability,technological,economicandsocial

aspectsshouldbeconsidered.

2.1 RAINWATER HARVESTING

2.1.1 UNLOCKING THE POTENTIAL OF RAINWATER HARVESTING

Forthepurposesofthisreport,“rainwater”willrefertoprecipitationthatiscollectedbeforeithitsthegroundandbecomes

runoff.Thisisanimportantdistinctiontomakebecause“stormwater”,whichhasalreadybecomerunoff,willgenerallyhave

differentcollectionsystems,contaminants,treatmentmethodsandenduses.

Thereisalotofmisunderstandingaboutthequalityandquantityofrainwater.Evaporatedwaterfromthelandforms

cloudsandeventuallybecomesrainfall,thequalityofwhichissimilartodistilledwater.Whenitfalls,itmaycontainsome

quantityofairpollutantsandparticulatematter,andintheuseofrooftopRWHsystems,somecontaminantsmaybepicked

upfromtheroof,particularlyifitisnotcleanedwell.Furtherchancesofcontaminationarepresentedifrainwaterrunsoff

ontostreetsanddrivewaysintostreamsandlocalcatchments;thelongerthedistance(mileage)thatrainwaterhastotravel,

thegreaterthechanceofcontamination.Inthewatercycle,rooftop-harvestedrainwaterhastheshortestmileage,and

thereforehasthelowestchanceofacquiringdissolvedandparticulatematter,asshowninFigure2.1.

Figure 2.1 Mileage of rainwater and total dissolved solids (TDS) (provided by Mooyoung Han).


RWHcollectsrainwaterfromrooftopsinastoragetank,butmostrainwaterstoragetanksinoperationhaveproblemsto

dowithwaterquality.Thewaterisoftenturbid,containingsuspendedsolidsoreventinyinsectsthatareeasilyobservable

tothenakedeye.Sometimes,thisisaresultofpoordesign,whichcreatesanobstacletoharvestingrainwaterforhuman

consumption.

CurrentprogressinscienceandtechnologyhascreatednewopportunitiesforRWHtobecomeasafesourceofpotable

water.Rainwaterisofhighqualitywhencollectedproperly,andpoor-qualityrainwaterisnotnecessarilyaresultofthewater

itself,butofinadequatesystemdesign,poormaintenanceofequipment(Dobrowskyet al.,2014)orincorrectsampling

methodsfromrainwatertanks.

Ingeneral,theonlycontaminantsinrainwatertanksareparticlesandmicroorganismsfromtheatmosphere(Kaushiket al.,2012),birddroppingsortheroofcatchment(Ahmed et al.,2012).Therefore,itrequiresminimaltreatmentbeforeusingitas

drinkingwater.Manystudieshaveevenreportedthatrainwatercanbeagoodqualitydrinkingwatersourcewithoutany

othertreatmentaslongasthecatchmentandtankaremanagedwell(Coombeset al.,2006;Leeet al.,2012).

Thereareseveralparticleremovalstrategiesusedwhencollectingrainwaterthatmaintainitsqualityinholdingtanks.

SpecificexamplesaredepictedinFigure2.2andareasfollows.

1. Biofilm:biofilminsidethetankmaximisesmicrobialactivitiesforself-purification(Kimet al.,2012;KimandHan,

2013,2014).

2. Calminlet:toavoidre-suspensionofsludge,inflowingenergyisdivertedupwardsbyusingatwo-elbow-typepipe,

allowingthesedimenttoremainundisturbed.

3. Inletbarrieranddrainpipe:sedimentiskeptinthefirstpartofthetank,andfromtimetotimeitisdrainedawayby

openingavalve.

4. Floatingsuction:flowerpollencansometimesenterthetankandfloatonthewatersurface.Bymakingthepipeinlet

10cmbelowthewaterlevel,onlycleanwateriscollected.

5. Siphonicdischarge:whenthewaterexceedsacertainlevel,anyscumfloatingatthesurfaceissiphonedoff.

Figure 2.2 Technical innovation in particle removal (provided by Mooyoung Han).

Finally,averyusefulmethodofremovingpossiblepathogensfromrainwaterissolardisinfection(SODIS).Thisinvolves

exposingrainwaterin2-Lpolyethyleneterephthalatebottlesinasolarcollectortosunlightforabout4–8hours.Complete

disinfectioncanusuallybeachieved,evenunderweakweatherconditions,byaddinginexpensivefoodpreservativessuchas

lemonandvinegar(AminandHan,2009,2011).


2.1.2 TACKLING RAINWATER SHORTAGE IN DRY SEASONS

Oneofthebarrierstousingrainwatertoitsfullpotentialisirregularrainfalldistributionoveracalendaryear.Rainwaterisnot

consideredareliablewatersourcebecauseoftheshortageofprecipitationduringthedryseason.Addingtothisproblem,

inmanyruralareas,localrainfalldata–whichareanessentialinputfordeterminingefficientsystemdesign–arenot

available.

Tocopewithwatershortageduringdryperiods,systemscanbecarefullydesignedthroughsimulationmodelling(Mun

andHan,2012).Optimumtankvolumecanbecalculatedwithcatchmentareamappingandtheinputofrainfallandwater

consumptiondata.Strategiestorestrictwaterconsumptionbasedontheremainingwaterinthetankcanthenreducethe

numberofnowaterdays(NWDs)thatoccur(Mwamilaet al.,2015).Anotherwaytoreducewatershortageistodevelopa

site-specificwatersupplysystemwithdualsources:forexample,rainwaterfordrinkingpurposesandgroundwaterforother

domesticpurposesatsitescontaminatedbyarsenic(NguyenandHan,2014).

2.1.3 CHALLENGES AND CONSIDERATIONS IN RWH IMPLEMENTATION

RWHhaslongbeenapopularpracticeatsmalltomediumscales,particularlyinruralandperi-urbanareas.Adoptionrates

forRWHpracticesarenowrisinginurbanareas,andthescaleofthesesolutionsisincreasing.AccordingtoBelmeziti

et al.(2014),15%oftheinhabitantsofFranceareconnectedtoaRWHsystem.Theyinvestigatedthequantityofpotable

waterthatcanbesavedbyapplyingRWHtoalargeurbanarea,inthiscasetheParisagglomeration.Usinggeographic

informationsystem(GIS)-derivedestimationsoftotalrooftoparea,annualprecipitationandtotalwaterdemand,they

concludedthatabout81millionm3peryear–11%ofthearea’spotablewaterdemand–canbereplacedbyrainwaterfor

non-potableuses.

Biswaset al.(2009)conductedasimilarstudyinDwarka,andidentifiedaveragepotentialwatersavingsof16.8%

throughRWH.Themosteffectiveareasinwhichtoharvestanduserainwaterarethosethataredenselypopulatedbecause

thismaximisestheratioofinhabitantstorooftoparea,allowingwatertobeusedmorefullyifcollectionsystemsareefficient

(Chananet al.,2010).However,thesefindingsdonotspeaktotheeconomicfeasibilityoffullimplementation;incentives

oftenstillneedtobeinplacetoencourageinstallationofRWHsystems.

Historically,RWHhasbeenmostcommonlyimplementedinaridandsemi-aridregionsbecauseofthelackoffreshwater

ingroundandsurfacewaterreserves,butclimatechangeandpopulationgrowthhaveresultedinthedepletionofwater

resourcesinmanyhumidregionsthatwereformerlyperceivedaswaterrich.ThishasnecessitatedtheuseofRWH

systemsinareassuchastheUnitedStatesandWesternEurope,andtheadditionalbenefitsofrunoffandpeakflow

reductionmakethesesetupsmoreattractivetobusinessesandmunicipalities.RWHalsocreatesopportunitiesfor

decentralisation,asitcanbeusedclosetothesource,reducingtheneedforlarge-scaletreatmentanddistributionsystems

(DeBusket al.,2013).

DeBusket al.(2013)statedthatautomatedRWHsystemsthatwithdrawwateratregularintervalsforspecificenduses

andarelinkedtoabackupwatersupplyaresuperior,astheypreventsystemoverflow,decreasepotablewaterdemandand

reduceoreliminatethelabourneededintheiroperation.Inadditiontothis,itisrecommendedtohaveanalarmorwarning

lightthatalertsuserswhenasystemmalfunctions,waterlevelsareloworpotablewaterisbeingusedinplaceofrainwater.

Inareasthatdonotsufferfromseverewatershortages,thereissometimesalackofincentivetoimplementRWH

becausethecostofimplementationintheseregionsmayexceedpotentialwatersavings–aproblemthatisexacerbatedby

subsidisationofwatersupplies.RWHsystemsalsohavelimitedefficacyifthecollectedwaterisnotused.Ifsystemsare

keptatcapacityandnotsubjecttoregularwithdrawals,overfloweventswillbepronetooccurringandthesystemwillyield

fewerbenefits(DeBusket al.,2013).

TheresponsibilityofhomeownerstocleanandmaintaintheirRWHsystemsisessential.Inmanypartsoftheworld,itis

commonforhousestohaverooftopRWHsystems,butnotalluserstakenecessarysafetymeasures.Thismostlybecomes

anissuewhenthesystemsinquestioncollectwaterforpotableuses.AstudybyStumpet al.(2012)assessedthe

demographicsandpracticesofhouseholdRWHsystemusersintheUnitedStatesandfoundthattestingofwaterqualityin

thetankswasinfrequent.Infact,theresultsofthestudyshowedthat64%ofparticipantsnevertestedforcontaminantsin

theirrainwatertanks.Althoughthesesetupsusuallydohavetreatmentsystemssuitedtotheexpectedenduse,certain

contaminantsmaypersist,includinglead,whichcanharmyoungchildrenandfoetuses,eveninverysmallquantities.Inthe

studybyStumpet al.,leadwaspresentinsomeofthecollectedsamples,buttheuseofafirst-flushdevicedecreased

concentrationssignificantly,suggestingthatatmosphericdepositionisoccurring.


2.1.4 FUTURE OF RAINWATER HARVESTING

2.1.4.1 RWH as a tool to increase the resilience of urban water systems

DecentralisedRWHhashighpotentialinincreasingtheresilienceofurbanwatersystems.Itcanbeusedasabackup

systemwhenthewatersupplyhastemporarilystoppedowingtoasuddenpowerfailure,pipebreakdownornatural

disaster.RWHcanalsomitigatefloodingwithoutincreasingtheexistingsewercapacity,andlocallystoredrainwatercanbe

suppliedforfirefightingtoextinguishfiresintheirearlystages.Reducingpotablewaterconsumptionfromthemainwater

supplybysubstitutingrainwaterfornon-potableusescanalsoreducetheenergyrequiredtotreatanddistributewater,

therebyreducingthecarbonfootprintofthewholenetwork.Furthermore,whenrainwaterisusedtosupplycleanwaterin

developingcountries,itcontributestotheUnitedNations’SustainableDevelopmentGoal(SDG)6,ensuringavailabilityand

sustainablemanagementofwaterandsanitationforall.

2.1.4.2 Multi-purpose RWH and management

AlthoughthereisgrowingglobalawarenessofthebenefitsofRWHthroughsuccessfulRWHprojects,moreeffortputinto

raisingpublicawarenessisneededintheformofmoretangibleincentivestopromotetheinstallationofRWHsystems.

ThemainreasonfortheslowpromotionofRWHistheeconomicfeasibility;thecostoftapwaterisoftentoolowto

justifytheinitialsetupcostsofmostRWHsystems.Thisistrueinmostdevelopedcountrieswherewatersupplysystems

aregenerallyveryestablishedandcomprehensive.However,bytakingintoaccountotherbenefitssuchasfloodmitigation

andcontingencyplanning,multi-purposeRWHsystemscanbeseenasmoreeconomicallyfeasible.ThecaseoftheStar

Citymulti-purposeRWHsystemisanexample,andwillbediscussedingreaterdetailinsection6.10.

Providingeconomicincentivessuchassubsidies,taxexemptionsorequivalentsmayhelptoencourageRWHasa

practice.Publicawarenesscanbeincreased,especiallyamongchildren,byofferingenvironmentaleducationinschools,and

includinginformationonwaterconservation,harvestingandreuse.

2.1.4.3 Rainwater management using IT

SeoulCityannouncedanewregulationtoenforcetheinstallationofRWHsystemsinDecember2004,aschematicof

whichcanbeseeninFigure2.3.Themainpurposeistomitigateurbanflooding,andthesecondarypurposeistoconserve

water.Asaresult,itaimstoensurethesafetyofthecityandimprovethewellbeingofcitizens.Aspartoftheprogramme,

thecityaskscitizenstovoluntarilycooperatebyfillingandemptyingrainwatertanksaccordingtodirectionsfromthe

disasterpreventionagency.

Figure 2.3 Monitoring of a multi-tank system for urban flood prevention and water conservation using IT (provided by Mooyoung Han).


Aspecialfeatureofthenewsystemistoprovideanetworkforthemonitoringofwaterlevelsinallwatertanksbythe

centraldisasterpreventionagency.Dependingontheexpectedrainfall,theagencymayissueanordertobuildingownersto

emptytheirrainwatertanksfullyorpartly.Anincentiveprogrammeisinplaceforthosewhofollowthegovernment’s

instructionsandthereissomepunishmentforthosewhodonot.Afterastormevent,thestoredwatercanbeusedfor

firefightingand/ormiscellaneouspurposessuchastoiletflushingandgardening.

2.2 STORMWATER COLLECTION AND MANAGEMENT

Stormwaterrunoffcanalsobecollectedforuse,buttreatmentmethodsgenerallydifferfromthoseusedinrooftop-

harvestedrainwater.Constructedwetlands(CWs)–consistingofvegetation,supportingsubstrateandlivingorganisms

–areafrequentlyusedsystembothtotreatandtostorestormwater.Macrophytesfacilitatethesedimentationofsolidsand

removecertainpollutantsfromthewater;watercolumnstransportpollutantstoactivebiologicalzonesandprovideideal

environmentsinwhichbiochemicaltreatmentprocessescanoccur;andlivingorganismspresentinthewetlandsystemaid

inthetransformationandrecyclingofsomechemicalsubstancesfoundinstormwaterrunoff(Chananet al.,2010).The

addedrecreationalandaestheticvaluemakesconstructedwetlandsidealforurbanareaswheredevelopmenthasledtoa

lossofgreenspace.

Thecollectionofstormwaterrunoffcanbeaneffectivewaytoreduceflooding,streambankerosion,waterpollution,

seweroverflowandotherissueslinkedtoincreasedrunoffgeneration,andmayevenhelptosupplementtheexistingwater

supply.However,someexpertswarnthattheover-extractionofstormwatercanbedetrimentaltostreamhealthand

environmentalflows.Stormwatercollectionregimesshouldbeoptimisedbothtomeeturbanwaterrequirementsandto

restorethehydrologicalprofileoftheareatoasclosetopre-developmentconditionsaspossible(Fletcheret al.,2007).

Figure 2.4 Differences in runoff pathways between water collected by storm drain and water collected by rooftop RWH. Collected stormwater passes over more impermeable surface area than rainwater, and therefore tends to have lower quality (provided by Mooyoung Han).

Oneofthebarrierstocollectingstormwaterrunoff–particularlyinurbanareas–isthehigh-levelcontaminationthatis

generallypresentafterithaspassedoverdirty,impermeablesurfaces(Figure2.4).Forthisreason,stormwaterisgenerally

onlycollectedfornon-potableuses(McArdleet al.,2010).

Bothrainwaterandstormwatercanbeusedforcropirrigation,reducingpotable-qualitywateruseinagriculture.However,

theymustbeusedefficiently,asthecollectionofprecipitationsolelyforirrigationcanbecomeproblematicforseveral

reasons.Thefirstoftheseisthepropensityfortankstooverflowandcreaterunoff-relatedissuesduringnon-growing

seasons.Additionally,inmanycountries,thetimeofyearwhenthemostwaterisneededforirrigationisthetimewhenthe

leastprecipitationisreceived.Therefore,rainwaterforirrigationisbeststoredusinglargetankswithcontrolstoenablethe

slowreleaseofwater,andtohaveabackupusageforthecollectedwatertopreventoverflowduringrainyseasons

(DeBusket al.,2013).

2.3 INFILTRATION AND GREEN ROOFS

Theencouragementofnaturalinfiltrationprocessesisawayinwhichmanyregionschoosetomanagestormwater.Notonly

doesenhancingtheinfiltrativecapacityofanareareducepeakflows,floodriskandrunoff,butthisprocessspeedsupthe


rechargeofaquifers,thuscontributingtotheusablefreshwatersupply.Low-impactdevelopment(LID)measuressuchas

permeablepavements,infiltrationgalleries/trenches,bio-retentionsubstratesandgrassswalesarepopularandeffective

meansofincreasinginfiltrationrates.

Liaoet al.(2013)completedastudycomparingtheefficacyoffivedifferent(mostlyinfiltration-based)LIDmethodsin

reducingpeakflowandcontrollingrunoffinurbansub-catchmentswithgreaterthan80%imperviousness.Themethods

includedbio-retention,infiltrationtrenches,permeablepavers,grassswalesandrainbarrels.Theresultsofthestudyare

displayedinFigure2.5,andsuggestthatinfiltrationtrenchesandrainbarrels(i.e.RWH)arethemosteffectivemethodsof

reducingpeakflow,andthesetwo,aswellaspermeablepavers,arethemosteffectivemethodsofreducingtherunoff

coefficientofsub-catchments.

0ZMJ7 ZMJ10 ZMJ57

1000

2000

3000

4000

Pea

k flo

w (

L/S

)

5000

Baseline SimulateBio-RetentionInfiltration TrenchPermeable PavementsRain BarrelsGrass Swale

0.0ZMJ7 ZMJ10 ZMJ57

0.2

0.4

0.6

0.8

Run

off c

oeffi

cien

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1.0

(b)(a) Baseline SimulateBio-RetentionInfiltration TrenchPermeable PavementsRain BarrelsGrass Swale

Figure 2.5 Effects of five different LID stormwater management techniques on peak flow and runoff coefficient (reprinted from Water Science & Technology 68 (12), 2559–2567 (2013) with permission from the copyright holders, IWA Publishing).

Insomearidorsemi-aridregionsinwhichconventionalRWHsystemsarenotfeasible,butgreaterwateravailabilityis

neededforagriculture,infiltration-basedin situRWHpracticesmaybeused.Thesemethodsinvolvecreatingmicro-

catchmentsinfarmfieldsaswellasmanipulatingvegetationcovertoreduceevaporation,enhanceinfiltrationandincrease

theavailabilityofwaterattherootzone.Anexampleofsuchamethodisthehalf-moonsordemi-lunespicturedinFigure

2.6,whichcapturerainwaterandkeepitonthefield(VohlandandBarry,2009).VohlandandBarry(2009)performeda

studyontheefficacyofin situRWHpracticesinsub-SaharanAfrica,andfoundthatthesesystemshaveanoverallpositive

effectoninfiltration,groundwaterrecharge,biomassproductionandsoilwaterstorage.

Figure 2.6 Man-made demi-lunes created in an agricultural field (Vohland and Barry, 2009).

Greenroofsandurbanfarmingdonotactuallyinfiltraterainwater;however,theycanreducestormwaterrunoff.Theheat

islandproblemcommoninlargecitiescanalsobemitigatedbythecreationofvegetatedgreenroofs,andsomefoodcan

beproducedinadditiontotheformationofanewcommunitygatheringspace.Anewparadigmofconcave-typegreenroofs

aspartofthewater–energy–foodnexusisrecognised,andhasreceivedseveralinternationalawards.


3 WATER REUSE AND DESALINATION

3.1 WATER REUSE

Reusingwaterenhancespotentialforconservingexistingfreshwaterresources,manyofwhicharebeingusedbeyond

sustainablelevels.Additionally,waterreuseisamorereliablesourcethanpumpedsurfaceandgroundwaterinsomeareas,

asitislesssensitivetodroughtconditionsandincreaseddemand.Notonlydoesthishelptoensurethequantityofwaterin

lakes,riversandaquifers,butdirectwaterreusepreventsthedeteriorationofwaterqualitysincetheactofdischarging

wastewaterintotheenvironmentcanleadtotheaccumulationofpersistentchemicalsinwater,floraandfauna.

3.1.1 POTABLE WATER REUSE

Recyclingwaterforpotablereuseisbecomingincreasinglypopular.Animportantconsiderationintheseusesisthattherisk

ofillnessfromcontaminationbeextremelylow.Allplantsdesignedtoreusewater–eitherdirectlyorindirectly–should

haveadditionalredundanciesinplacetominimisetheriskofdistributingcontaminantsofconcern(Rietveldet al.,2011).

Indirectpotablereuse(IPR)isthetreatmentofreclaimedwatertodrinkingstandardsafterithasbeendischargedintoa

surfaceorgroundwaterreservoir(Figure3.1).Wastewatermayundergoeitheradvancedorbasictreatmentbeforereaching

theenvironment,butthoroughpurificationmustoccurbeforeitisaddedtothecommunitysupply.TheideabehindIPRis

thatdischargingwaterintotheenvironmentfirstcreatesabuffer,astheprocessesofdispersion,infiltrationandnutrient

uptakebyplantsremovesomeunwantedcontaminants(Leverenzet al.,2011).Itiscommonlyusedaroundtheworld,and

existsbothinaplannedandinanunplanned(de facto)capacity.

Figure 3.1 The pathway of water in IPR, which can use either conventional or advanced wastewater treatment processes (based on Raucher and Tchobanoglous, 2014).

IPRcanproducehigh-qualitydrinkingwaterandisanimportantresourceoptionglobally,butLeverenzet al.(2011)

suggestthatdirectpotablereuse(DPR)maybepreferable,asfewerstepsinthetreatmentprocesscansavecostsand

energy,aswellasreducedischargeofwastestotheenvironment.DPRinvolvestreatingreclaimedwatertodrinking

standardsanddirectlyblendingitwiththepotablewatersupply.InDPR,anengineeredstoragebuffer(ESB)canbeused

inplaceoftheenvironmentalbufferusedinIPR,butisnotmandatory(Figure3.2).Also,IPRmaynotbeanoptioninall

areas,assomecommunitiesdonothavesufficientgroundwaterorsurfacewaterresourcestobehaveasenvironmental

buffers(RaucherandTchobanoglous,2014).

DPRofreclaimedwaterisoftenviewedasapromisingresourceoptionforthefuture.Itreducesthestrainonexisting

surfaceandgroundwatersourcesandeliminatestheneedforaseparatedistributionsystem,whichisnecessarywhen

reclaimingwaterfornon-potableuses.DPRwasfirstimplementedin1969inWindhoek,Namibia(seesection6.6),and

evenatthattimeprovidedasafedrinkingwatersupply(DrewesandKhan,2015).Owingtothecontinualimprovementof

watertreatmenttechnology,itispossibletoreducetheconcentrationsofharmfulcontaminantsinwaterdowntominute

quantitiesthatdonotthreatenhumanhealth.DPRmayalsobelessexpensive,lessenergyintensiveandlesscomplicated

toimplementthanotherwaterresourceoptionsbecauseoftheabilitytoreusewaterlocallyratherthantransportingitlong

distances(Leverenzet al.,2011).


Firstly,sourcewatercanvarywidelyitsbiological,chemicalandmineralcomponents,whichiswhyitisimportanttoknow

whatkindofeffluentisbeingdischargedandhowitisregulated.Fullknowledgeofsourcewaterqualityiskeyindeciding

onappropriatetreatmentmethods,andthereforecomprehensivewaterqualitymonitoringshouldbeperformed.Morerobust

systemreliabilitycanbeensuredbycreatingredundancywithmultiplebarriers,enablingtheremovalofawidevarietyof

contaminantsanddesigningresponseplanstoeffectivelymitigatesystemfailures.Aftertreatment,watermustbestoredor

blendedwithotherwatersuppliesbeforedistribution;makingsurethatqualityismaintaineduntilitreachestheconsumer

(DrewesandKhan,2015).

Oneprominentchallengeinwaterreuse–particularlypotablereuse–liesincommunityacceptance;manypeople

areinherentlyaversetodrinkingorusingreclaimedwater.BrownandDavies(2007)conductedastudyassessingthe

communityreceptivitytowaterreuseinaregionofSydney,Australia,andfoundthatpeoples’aversiontowaterreuse

increasedasusesbecamemorepersonal.Table3.1showsthattheacceptanceofrainwaterforalmostallpracticesis

higherthanthatofgreywater,withonly2%acceptingtreatedgreywaterfordrinking.Giventhatthestudywasperformedin

Australia–whereissuesofwaterscarcityareinherentlywellknown–acceptanceofwaterreusepracticesmaybeeven

lowerincountrieswithmoreabundantwatersupplies.Waterprofessionalsaremakingeffortstochangethepublic’s

perceptionofreusedwater.AsLouisvanVuurenoftheNationalInstituteofWaterResearchSouthAfricasaid,“Water

shouldnotbejudgedbyitshistory,butbyitsquality”(Roux,2013).

Figure 3.2 The pathway of water in DPR, which can operate without an ESB (based on Raucher and Tchobanoglous, 2014).

Figure 3.3 Key considerations in the planning and implementation of potable water reuse schemes (reprinted from Journal of Water Reuse and Desalination 5 (1), 1–7 (2015) with permission from the copyright holders, IWA Publishing).

Source WaterCharacteristics

ReliableTreatmentSystems

Storage andBlending

• Source control• Influent monitoring• Flow equalization

• Pilot testing of conventional and advanced processes• Redundancy, robustness, resilience• Performance monitoring/Analytical methods• Emergency facilities

• Introduction into drinking water system• Mineral balance• Disinfection residual• Blending with other supplies

Whetherpotablereuseisdirectorindirect,thereareafewkeyelementsofeverywaterreuseprojectthatmustbe

incorporatedintoitsdesign(Figure3.3;DrewesandKhan,2015).


3.1.2 NON-POTABLE REUSE

Non-potablereuseisanimportantapplicationofreclaimedwater,asitcanbesubstitutedforpotablewatertoconservethe

totalsupply.Potentialusesofnon-potablereclaimedwaterincludeagriculturalirrigation,industrialprocesses,street

washing,toiletflushingandlandscaping.Diversifyingnon-potablewaterreusepracticesandimprovingsystemefficiency

maybekeyfactorsinconservingfreshwaterandmeetingdemand(Kalavrouziotiset al.,2015).

3.1.2.1 Agriculture and Landscape Irrigation

Oneoftheprimarynon-potableusesforreclaimedwaterisinagriculture.Reclaimedwatermayevenimproveagricultural

productivityowingtothehighnutrientcontent,andreducingcostsspentonfertiliserwhilestillproducingahighcropyield.

Carret al.(2011)performedacasestudyonthreedifferentresearchsitesinJordan,inwhichrecycledwaterwasusedfor

cropirrigation.Theplant-beneficialnutrientsthatwaterwastestedforwerepotassium,phosphate,sulphateandmagnesium,

andbarleywasthetestcropbeinggrownateachresearchsite(Figure3.4).

Table 3.1 Percentage of study participants who would be open to using either filtered rainwater or treated recycled greywater for several different end uses (reprinted from Water Science & Technology 55 (4), 283–290 (2007) with permission from the copyright holders, IWA Publishing).

Use Filtered rainwater Treated recycled greywater

Drinking 28% 2%Cooking 32% 3%Showering 59% 13%Washingclothes 69% 31%Washingcar 85% 77%Rushingtoilet 85% 87%Wateringgarden 94% 95%

Figure 3.4 Quantity of each plant beneficial nutrient applied to three study fields – Kirbet As Samra (direct), Ramtha (direct) and Deit Alla (indirect) – compared with the average quantity of each nutrient that can be taken up by barley (reprinted from Water Science & Technology 63 (1), 10–15 (2011) with permission from the copyright holders, IWA Publishing).

Kirbet AsSamra

Ramtha Deir Alla Nutrient uptakeof barley

220200180160140120100806040200

Sol

ute

quan

tity

appl

ied

(kg

hect

are-

1)

PotassiumPhosphateSulphateMagnesium

Theauthorsestablishedthatthenutrientsfoundinreclaimedwaterweregenerallysufficienttomeettheneedsoffarmers,

sometimeswithsupplementaryfertiliserneeded.Thisallowedboththeconservationoflimitedfreshwaterresources,as

wellasareductioninfertiliserneeds,allowingfarmerstoreducecosts.Carret al.(2011)statethatwiththecontinual

applicationofreclaimedwatertoagriculturalfields,thepotassiumandphosphatecontentofsoilscanbeenhanced,

leadingtoincreasedproductivity.However,excessivequantitiesofsulphateandmagnesiuminsoilscanreduceagricultural

productivity;thereforethesenutrientsshouldbemonitoredcarefully.Animportantconditionisthatfarmersbewelleducated

aboutthenutrientcontentoftheirirrigationwater,sothattheyknowhowmuch–ifany–fertilisertoapplytocrops,thus

maximisingthebenefitsassociatedwithreusingwaterforirrigation.FindingsbytheWorldBank(2015)suggestedthat

Bolivianfarmershadabroadunderstandingofissuesrelatedtowaterreuseforagriculturalirrigation,andconsequently

wishedtotakepartincommunityeffortstoincreaseagriculturalwaterreuse.

Greywatercanalsobeusedforirrigation,but,likewastewater,itmustundergosometreatmenttoremoveoil,grease,

surfactantsandothercompoundsbeforeitisappliedtocrops.Thisisbecausetheuseofrawgreywaterforirrigationcan


drasticallychangethesoilproperties,increasingthehydrophobicityofsoilparticlesandeventuallymakingthesoilunfitfor

agriculturalactivities(Traviset al.,2010).

Reclaimedwateralsohaspotentialusesinlandscapeirrigation,includingparks,cemeteries,golfcoursesandother

non-agriculturalspaces.Thishelpstocurbtheexcessiveuseofpotablewaterfornon-drinkingpurposes,especiallyin

summertime.Thiswateralsogenerallydoesnotneedtoundergodisinfection,thereforereducingenergyrequirements

(Haeringet al.,2009).

3.1.2.2 Industrial Use

Reclaimedwaterhasextensiveusesinindustrybecausewaterqualityguidelinestendtobelessstrictandtheneedfor

potablewaterisreducedoreliminated.Industrialprocessesthatutilisereclaimedwaterincludeevaporativecooling,boiler

feed,washingandmixing(CharteredInstitutionofWaterandEnvironmentalManagement,2012).

AnexampleinwhichthishasbeenimplementedistheGippslandWaterFactory(GWF)inAustralia,whichtreats

domesticwastewateraswellasthatofanearbypulpandpapermill.Thefacilityusesprimarysedimentation,anaerobic

reactors,nutrientremovalbyactivatedsludgeandreverseosmosis(RO).TheGWFcreatesadrought-resistantwatersupply

forindustrialcustomers,andreducesthequantity/increasesthequalityofeffluentdischargedtothenearbyregionaloutfall

system(ROS)(Daiggeret al.,2013).

AnothergoodexampleofindustrialwaterreuseisinTerneuzen,TheNetherlands.TheDOWChemicalmanufacturing

plantusesanintegratedmembranesystem(IMS),consistingofcontinuousmicrofiltrationandtwo-stagesofRO.Asa

result,high-qualityreclaimedwaterisproducedusingsignificantlylessenergyandfewerchemicalsthanwouldbeusedto

desalinateseawatertothesamequality(Rietveldet al.,2011).

Analternativemethodofreusingwaterinamainlyindustrialsettingiscascading,inwhicheffluentfromoneindustrialuser

ispumpeddirectlytoanother;providedtheeffluentqualityofthefirstuserishigherthanthemandatedinfluentqualityof

thesecond.Thorenet al.(2012)performedastudylookingathowwaterreusepotentialcouldbemaximisedinVancouver,

Canada.Usingwaterqualityguidelines,influentandeffluentvolumeandlocationofplants,theyassessedthreedifferent

scenariostoseewhichprovidedthegreatestopportunityforwaterreuseatthelowestcostandenergyexpenditure.Since

theguidelinesinplacerequirethiswatertobeprocessedbeforeitcanbereused,cascadingisnotacost-orenergy-

efficientreuseoptionunlesssatellitewaterreclamationfacilitiesaresituatedinthecentreofindustrialareastotreateffluent

frommultipleusersbeforeitisreallocated.Expandingnetworkstoincludenotonlyindustrialusersbutalsocommercial,

institutionalandmulti-familyresidentialuserswouldfurtherincreasetheefficiencyofthesystemandthequantityofwater

saved(Thorenet al.,2012).However,thistypeofschemetakesadecentralisedapproachtowaterreuse,whichmaynot

beinlinewiththegoalsofalldecision-makers,whomaydisplayreluctanceduetoperceivedrisksandinsteadfavour

centralisation,whichismorecommonindevelopedcountries(Domènech,2011).

3.1.3 GREYWATER REUSE

Bothgreywaterandblackwatercanbereclaimedforfurtheruse.However,sincetheircompositionscanvarydramatically,

thetreatmentprocessesusedmustvaryaswell.Greywatercanbedefinedasanywaterusedinhomesorofficebuildings

excludingthatwhichcontainsfaecalmatter.Themainpollutantsofconcerningreywaterarechemicalcontaminantsfrom

detergents,personalcareproducts,bleachesanddyes.However,microbialcontaminantsarealsoaconcern.While

greywaterhasfewermicroorganismsthandoesblackwater,theconcentrationsofheavymetals,nutrientsandchemicalsare

oftensimilar(Warner,2006).

Onechallengeintreatinggreywateristhehighvarianceincompositionbysource.Greywatercollectedfromakitchen

sinkordishwashermaycontaingreaseandanimalfats,whilewatercollectedfromawashingmachineoftencontainstiny,

non-biodegradablefibresfromclothing.Forthisreason,itisvitaltofiltergreywaterfirsttoremovefibres,celluloseand

grease,andtochangefiltersregularlytopreventclogging.Misinformationtohomeownerscanalsobecomeanissue,as

monitoringandmaintainingon-sitegreywatertreatmentsystemsisoftenleftuptotheowner,whomayormaynothavefull

understandingoftherisksinvolved.Ifasystemmalfunctionsorwaterisusedforincorrectpurposes,theconsequencescan

besevere(Warner,2006).

Anexampleofhowgreywatercanbeintegratedintoamorecomplexsystemistheproposed“GreenVillage”attheDelft

UniversityofTechnology,whichaimstobeanautarkicsystemthroughtheuseofefficienttechnology,greywaterreuseand

RWH(Figure3.5).Builtfrom30recycledshippingcontainersmadeintoofficespaces,dormitories,bathrooms,alunchroom

andalaboratory,theprojectstressesdecentralisationanda“fit-for-purpose”watersupply.DrinkingwaterintheGreen

Villagewillcomefrom100%recycledsources:53%fromrecycledgreywaterand47%fromrainwater.Greywaterwillbe


subjecttoatriplebarrierofultrafiltration(UF),UVdisinfectionandozonation,whilerainwaterwillonlybesubjecttoUFand

UV(vanderHoeket al.,2014).

TheGreenVillagewillutiliselowwaterconsumptionappliances–includingvacuumflushtoiletsrequiringabout1Lper

flush–andblackwaterwillbetreatedbyanupflowanaerobicsludgebioreactor(UASB)toproducebiogas,beforebeing

divertedtoaverticalflowconstructedwetlandforsecondarytreatment(vanderHoeket al.,2014).Italsoaimstointegrate

variousmethodsandprinciplesofsustainablewatermanagementintoonedesign.Bylimitingwaterconsumptionthrough

water-savingdevices,treatinggreywaterandrainwaterfordrinkingandotheruses,andproducingenergythroughanaerobic

digestionofwaste,thevillagecanhaveanautarkicwatersupplyandhavearelativelysmallenergyfootprint.VanderHoek

et al.(2014)indicatethattheadditionofwindorsolarenergywouldcreateanautarkicenergysupplyaswell,butthese

aspectshavenotyetbeenincorporatedintotheprojectdesign.

Thereareanincreasingnumberofregulationsmakingacertaindegreeofreusemandatory,particularlyinverywater-

scarcecountries.ThiscanbeseeninIndia,wheretheNationalEnvironmentalPolicystatesthat,asof2006,allnew

buildingsmeetingaspecificsetofcriteriamustincludeawaterrecyclingplanttohelpsupplementthewatersupply.Ontop

ofthis,smallerbuildingsareofferedpropertytaxcreditstoimplementwaterreuse,eventhoughitisnotrequiredbylaw

(Barringer,2014).

3.2 DESALINATION AND SALINE WATER USE

Desalinationisthoughttobeabletoeithergreatlyreduceorcompletelyeliminatewaterscarcityissuesinaridandsemi-arid

regions(ElSalibyet al.,2009).Coastalareasorthoselyingabovesalinegroundwaterreservesoftenhavelimited

freshwateroptions,somakingdesalinationtechnologiesviableandaccessibleintheseregionscouldhelpahighproportion

oftheglobalpopulationtomeettheirwaterneeds.Unfortunately,conventionaldesalinationtechnologiesgenerallystillcarry

highcostsintermsofmoney,energyandenvironmentaldamage,includinggreenhousegasemissions,disruptionofmarine

lifeinconstructionphasesandatplantintakepoints,andthedischargeofchemical-containingsalinebrinethatposesrisks

tomarineecosystems(LattemannandHöpner,2008;BatenandStummeyer,2013).However,theprocessofdesalination

hasbecomemoresustainableandcost-effectiveovertime,andnewandemergingdesalinationmethodsmayhavethe

potentialtoincreasethesustainabilityoftheprocessfurther.Someexpertsevenstatethatitisbecomingpossibleto

desalinateseawaterusinglessthan2.0kWhpercubicmetre,anoveldevelopment(Macharg,2011).

Figure 3.5 Treatment processes to be used in proposed Green Village at the Delft University of Technology (reprinted from Journal of Water Reuse and Desalination 4 (3), pp 154–163 (2014) with permission from the copyright holders, IWA Publishing).


3.2.1 REVERSE OSMOSIS (RO)

In2013,thetotalglobaldesalinationcapacitywasdominatedbyRO,whichaccountedfor59%ofcapacity(Nget al.,2013),andthismarketshareiscontinuallygrowing,asistheenergyefficiencyofROtechnology(BatenandStummeyer,

2013).Macedonioet al.(2012)listROtechnologyasthemostpromisingamongmembranetechniquesbecauseitremoves

smallercontaminants–includingsomepharmaceuticalcompounds–andcarriesasmallercarbonfootprintthanmanyother

desalinationtechnologies.Itsdrawbackslieinthelargenumberofjointsandconnectionsintheprocess,theneedfor

additionalpre-treatmentandpost-treatmentstagestoensureadequatesystemperformance,andtheremovalofcertain

mineralsthatmayactuallybedesiredindrinkingwater(Macedonioet al.,2012).Mogheiret al.(2013)suggestthat

improvingthepre-treatmentprocessusingnanofiltration(NF)couldbothimprovewaterrecoveryratesandprolongthelife

ofROmembranesbyreducingscalingandfouling.

ROplantsdischargebrinethatis100%moresalinethantheinfluentconcentration,butisthesametemperatureas

seawater.Thisisincontrasttomultiple-effectdistillation(MED)andmulti-stageflash(MSF)desalinationplants,which

dischargebrineabout15%moresalinethanseawater,but5°Cto10°Cwarmer.Ofthesetwofactors,increased

temperaturehasgreaternegativeimpactsonmarineecosystems.Therefore,despitethehighsalinityofROdischarge,itis

moreenvironmentallysound(Al-KaraghouliandKazmerski,2013).

ROdesalinationisalsodescribedasbeingmorecost-effectivethanthermaldesalinationmethodsbyseveralexperts.

Wittholzet al.(2008)completedacostcomparisonofthemostcommondesalinationmethods,includingMSF,MEDand

RO,andboththecapitalcostsandoperatingcostsoftheROtechnologieswerelower(Figure3.6),whichbodeswellfor

theimplementationofdesalinationinlower-incomecountries.

Figure 3.6 Capital and per unit costs of desalinating water by four different methods (Wittholz et al., 2008).

900.00

800.00

700.00

SWROBWROMSFMED600.00

500.00

Cap

ital C

ost (

US

D·1

06 )

400.00

300.00

200.00

100.00

0.000 200000 400000

Capacity (m3/d)

600000

2.50

2.00

1.50

SWROBWROMSFMED

1.00

0.50

UP

C (

US

D/m

3 )

0.000 200000 400000

Capacity (m3/d)

600000

3.2.2 OTHER NON-THERMAL DESALINATION

AlthoughROiscurrentlythemostwidelyusednon-thermaldesalinationtechnology–aswellasthemostcommercially

viable–manyotherpromisingnon-thermalmethodsexist.

Ghyselbrechtet al.(2013)reportthatelectrodialysis(ED)technologyisbecomingincreasinglypopularowingtoitsability

torecoverionsintheprocess,andaccordingtoTurek(2003),EDcanbeascost-effectiveasRO.However,thecostofED

isdirectlyproportionaltothefeedwatersalinity,soitmaybeinfeasibleforsaltwateraboveacertainconcentration.

Membranedistillation(MD)harnesseslowtemperatureheatsources(renewablesorwasteheat),usingminimalchemical

treatmentandelectricalenergy.SeveraltypesofMDexist,includingdirectcontactmembranedistillation(DCMD),sweeping

gasmembranedistillation(SGMD),airgapmembranedistillation,andfinally,vacuummembranedistillation(VMD),which

tendstohaveahigherfluxrateandlowersusceptibilitytofoulingthanothertypesofMD(RamezanianpourandSivakumar,

2015).

WiththeuseofVMDtechnology,lowtemperaturethermalenergyissuppliedinthefirststageoftheprocess,followedby

severalstagesofevaporationandcondensation(Mendez,2012).VMDhasremovalefficienciesofclose100%forallmajor

parametersofconcern,andremainseffectivewithincreasingfeedwatersalinitymethods(RamezanianpourandSivakumar,

2015).


Mendez(2012)statesthatVMD(Figure3.7)isalowmaintenancetechnology,andispronetominimalscalingand

fouling,resultingfromlowtemperatureheatutilisationandhydrophobicmembranes.Thistypeoftechnologymaybe

especiallyimportantinoff-gridlocationswhereconventionalenergyandreliablefreshwatersourcesarenotaccessible.The

applicationoflowtemperatureheatprovidesanopportunitytocouplethetechnologywithwasteheatrejectionstreamsor

renewableenergy,increasingitssustainability(Kemptonet al.,2010).

Anotherformofnon-thermaldesalinationisforwardosmosis(FO),whichusesahighlyconcentratedsolutiontodrawfeed

waterthroughamembrane.Sincethetechnologyusesosmoticpressureinsteadofhydraulicpressure–asisusedinRO

–itrequireslessenergy.MembranesarealsosubjecttolessscalingandfoulingthaninRO,especiallycombinedwith

microfiltration(MF)pre-treatment(Venketeswariet al.,2014).

Thereisevidencethatcouplingdifferentmembraneprocessesmayproduceahigher-qualityendproduct,whilereducing

oreliminatingeffluentbrine(Macedonioet al.,2012).GiventhepromisingaspectsofbothVMDandFOtechnologies,Li

et al. (2014)testedtheefficacyofacombinedFO/VMDsystemonhighlysalineshalegasdrillingflow-backfluid.Usingthe

twomechanismsconsecutively–firstFOwithaKCldrawsolution,thenVMD–waterrecoveryratesof90%efficiency

wereachieved,minimalscalingandfoulingoccurred,andtheresultantdischargehadaqualityresemblingbottledwater,

despitetheinitialpoorqualityofthefeedwater(Liet al.,2014).

3.2.3 THERMAL DESALINATION

Eventhoughthermaltechniquestendtobemoreenergyintensive,withhighercostsandgreaterenvironmentalfootprints

thannon-thermalmethods,theyarestillwidelyused;mainlyinMENAcountries(Macedonioet al.,2012).However,an

increasingnumberofstudiesdemonstratethebenefitsofcogenerationorpolygenerationbycombiningthermaldesalination

withenergygenerationasawaytoreduceenergyuse,costandby-productwaste.AccordingtoGudeet al.(2010),when

aMSFdesalinationplantisconnectedtoapowerplant,thespecificenergyrequiredtoproducefreshwaterissignificantly

lower.ThiswasdemonstratedinKuwait,whereastand-aloneMSFplantused290kJ/kgofenergytoproducefreshwater,

comparedwith160kJ/kgwhenconnectedtoanenergygenerationplant.

Similarly,Maraveret al.(2012)releasedastudyassessingtheviabilityofapolygenerationconfigurationtocreatethree

usefulendproducts:energyfrombiomass,desalinationandcooling.Theproposedsystemhasthreemainsubsystems:an

organicRankinecycle(ORC)engine,aMEDplantandalithiumbromide-watersimpleeffect(LBSE)absorptionchiller.The

systemisidealforisolatedareasinwhichfreshwateravailabilityispoor,butalgae,energycropsorresidualbiomasscanbe

foundeasily,suchasislands.Theauthorsdeemedthisittohaveahighfuelenergysavingsratio(FESR)andpredictedthat

theresultantcostsavingscouldequalinstallationcostsin4–20yearsdependingonthetypeofbiomassused.

Hybriddesalinationmethodscombineboththermalandnon-thermalprocesses,andgenerallyincludeROdesalination

combinedwithMSForMED.ThemostcommonandfeasiblesetupisaRO-MSFplant,whichrequireslowermonetaryand

energyinputsandachieveshigherwaterrecoveryratesthaneachprocessindividually,owingtocouplingofboththermal

andelectricalenergysources.ROcanbeeasilyintegratedintoexistingMSFplants,reducingtheneedforlargecapital

investments(Gudeet al.,2010).AccordingtoKaragiannisandSoldatos(2008),MSFseawaterdesalinationplantscan

Figure 3.7 Aquaver MD desalination unit (Mendez, 2012).

membrane

boiling solution

condensation foil

p1

steam

from external heatsource, i.e. powerplant

p2 p3 p4

concentrate

condenser

distillate

preheatedfeed


reducecostsbyupto15%byincorporatingRO,andmanystudieshavefoundthecombinationofthermalandnon-thermal

desalinationmethodstoimproveperformance,costeffectivenessandwaterrecoveryrates.

3.2.4 SALINE WATER USE

Salinewatercanalsobeuseddirectly–usuallyfortoiletflushing–withouttheneedfordesalination.Anexampleofthisis

inuseinHongKong,whereextremefreshwaterscarcityhasledtotheimplementationofadualwatersupply,whichuses

freshwaterforpotableusesandseawaterfortoiletflushing.AccordingtoLeunget al.(2012),thisdualsystemhasbeenin

placesincethe1950s,serves80%ofHongKong’sinhabitantsandhasresultedina20%reductionintotalwaterdemand.

Seawateristreatedwithchlorinetopreventmicrobialgrowthinthepipesystem,distributionpipesarelinedwithcement

mortar,andlong-lastingpolyethylenepipesareusedindoors.Seawater’slackofdiscerniblecolourorodourmakesitwidely

acceptedbyresidentsandtouristsinHongKong.Theoneprominentissuewiththissystemisthatthesalineconcentration

oftheeffluentdrasticallylimitswaterreuseoptions.

SaltwaterisalsobeingusedinQatarforevaporativecoolingandhumidificationingreenhouses.Thisallowsthecrops’

freshwaterrequirementstobeminimised,butsupportshighyieldsandreducestheneedtodesalinatewater,thus

minimisingthecarbonfootprintofthewholeproject(SaharaForestProject,nodate).

3.2.5 DEVELOPMENT ON LOW-ENERGY DESALINATION

Inallformsofdesalination,expenditureonenergy–eitherthermalorelectrical–makesupmorethanhalfofthetotal

operatingbudget,andthemajorityofdesalinationplantsworldwideusefossilfuelstomeettheirneeds(Batenand

Stummeyer,2013).Thisnotonlyleadstohighvolumesofgreenhousegasesbeingemitted,butasfossilfuelsbecome

scarcer,theirincreasingpricesmaymakedesalinationprohibitivelyexpensive.Therefore,thefuturesustainabilityof

desalinationwillbeinfluencedbytheabilitytoincreaseefficiencyintheprocesses,harnessrenewableenergy

sources(BatenandStummeyer,2013)and/orrecoverenergy,whichcanberecapturedfromhigh-pressurepumps

(Macharg,2011).

Renewableenergycanbeacontroversialtopicbecausemanyofthesesources–suchassolarphotovoltaic(PV),

concentratedsolarpower(CSP)andwind–havefluctuatingavailability(vonMedeazza,2004).Also,dependingonthe

technology,renewableenergy-powereddesalinationcanbesignificantlymoreexpensivethanwhereconventionalfuel

sourcesareused(Table3.2).However,thesecoststendtodecreasewithtimeandtechnologicalinnovation,andthe

environmentalbenefitsprovideanincentivetouserenewableenergyregardlessofcost(Gudeet al.,2010).

Table 3.2 Cost comparison (in US dollars) of various desalination methods coupled with either conventional or renewable energy (Gude et al., 2010).


Solarstillsmaybeidealforremoteareaswithextremewaterscarcityandlimitedaccesstoelectricity,sincetheyhave

beeninuseformanydecadesandaresimpletoconstruct,althoughthesemaynotbeviableonalargerscale.Solar

multi-effecthumidification(MEH)unitshavegreatercapacityandarestillrelativelysimple.Thelargestoperationusingthis

technologyhasbeenfunctioninginDubai,UAEsince2008,andconsistsofa156m2plant(Al-KaraghouliandKazmerski,

2013).

Therealsoexistseveralviablesystemsthatcouplerenewableenergywithconventionaldesalinationprocesses,suchas

PV-poweredROorEDdesalination.Althoughtheyrequireminimalenergytofunction,theyarerelativelyhigh-costoptions;

mostaccessibletowealthycountries.WindpowercanbecoupledwithROormechanicalvapour-compression(MVC)

technology,andworkswellinremoteareas,butmusteitherhaveacontrolsysteminplacetosmoothoutfluctuationsin

windpatterns,abackupbattery,oradditionalfreshwaterstoragecapacity(Al-KaraghouliandKazmerski,2013).Parket al.(2012)statethatthedevelopmentandapplicationofbetterenergybufferingmethodshasthepotentialtoimprovethe

viabilityofrenewableenergymembranetechnology,andprovidemorereliablewatersuppliesinareaswhereconnectingto

anenergygridisinfeasible.


4 DEMAND MANAGEMENT AND WATER LOSS REDUCTIONInconventionalwatermanagementscenarios,theusualresponsetoincreasedwaterdemand–drivenbypopulationand

incomegrowth–hastypicallybeentoincreasegroundwaterand/orsurfacewaterextractionrates.Thishasresultedin

environmentaldegradationandtheoveruseofseveralfreshwaterresources.Controllingdemandsothatlesswaterisused

isamoresustainableoption,andconsequently,manymunicipalitiesandutilitiesusemethodsforachievingthisresult(Table

4.1),suchaseconomicincentives,water-savingtechnologies,metering,awarenesscampaignsandleakreduction.In

general,demandmanagementeitherincentivisestheconservationofwaterresourcesorprovideswaystouselesswater

withoutalteringlifestyle.Measuresthatcontroldemandtendtobelessexpensive,lessenergyintensiveandcarrysmaller

environmentalfootprintsthanAWRtechnologiesthatactuallyaugmentsupply(Grant,2006).Thissectionwillexploreways

inwhichthisispossible.

Table 4.1 Demand management strategies for varying levels of intervention.

Level of intervention Mechanism

Policy Utilitycreditsforimplementingstormwatermanagement,RWH,waterreuseandotherbestpracticesforwatercyclemanagement

Financialincentives,taxexemptionandotheradvantagesofferedonwater-savingappliancesand/oruseofAWR

Certificationsofferedoneco-efficienthomesandbuildings(water/energymanagement)Amendmentofbuildingcodestoincludeconservation/demandmanagementmeasuresAvailabilityoffreewaterefficiency/usediagnosesforhomesandbusinessesImplementationandenforcementofregulationsonwateruseandwithdrawalPublicationoftechnicaldocumentsonbestwater-demandmanagementpractices,made

availabletopublicSupplier Installationofmetersthroughoutentiredistributionnetworkorforselectedusers

AppropriatevolumetricpricingstructuretoensurefairnessandfullcostrecoveryImplementationofefficienttoolsandmethodologiesforleakdetectionandrepairTrainingandeducationforstaffondemandmanagementPubliceducationandawarenesscampaignsApplicationofoperationalefficiencymeasures

Consumer Installationofwater-savingdevicesParticipationinwaterconservation-relatededucationprogrammesandworkshopsIncreasedawarenessofwaterusehabitsRegularmonitoringandsystemassessmenttodetectleaksand/orotherdamagesTimelyrepairofleaksanddamageddevicesandplumbingConservativeandresponsibleoutdoorwateruse,particularlyinsummermonthsSubstitutionoflowornon-waterusingpracticesinplaceofwaterintensivepracticeswhere

possibleUseofAWRwherepossible

4.1 ECONOMIC INCENTIVES

Thereareafewwaysinwhicheconomicincentivescanbeusedtoreducewaterdemandandwhicharegenerallyquite

effective.Theyincluderaisingwaterpricestowardsfullcostpricing,offeringrebatesonwaterbillsforinstallingcertain

watermanagementbestpracticesorofferingdirectrebatesonwater-savingappliances(Biswaset al.,2009).Manyplaces

intheworldstillhavesubsidisedpublicwatersupplies,wherethetruecostofproductionisnotreflectedinthepricepaid

byconsumers.Thisleadstothegradualdilapidationofinfrastructureduetolackofrevenue,andincentiviseswastage

(EuropeanEnvironmentAgency,2013).Ingeneral,higherwaterpricestendtocorrespondtolowerusageratesandvice

versa(Figure4.1).Also,higherpricesdonottendtoinfluencedemandfordrinkingwater,butexcessiveusessuchascar

washingandfillingswimmingpoolsaredecreased(EuropeanEnvironmentAgency,2013).Therefore,re-evaluatingmunicipal

waterpricingstructuresmaybeoneofthefirststepsinmanagingacountry’swaterdemand.


0 100 200 300 400 500 600 700

United States of AmericaChinese Taiwan

South KoreaItaly

MexicoJapan

SwedenIran

Hong Kong, ChinaMacao, China

CanadaFinland

SwitzerlandMauri�us

BrazilNorwayFranceCyprusAustria

England & WalesNetherlands

SpainBelgium

DenmarkBulgaria

RomaniaHungary

PolandPortugal

Israel

Specific water consump�on—Drinking water charge*consump�on in litres/capita/day and charge in US$ for 200 m³

Drinking water charge in US$ Specific consump�on in litres/capita/day

Figure 4.1 Comparison of water pricing versus consumption in select countries (International Water Association, 2014).

Animportantconsiderationwhenlookingtocreateamoreequitablepricingschemeisthetypeoffeestructure,ofwhich

manyexist.Householdsmayusebetweenonethirdandonehalflesswaterwhentheyaremeteredandchargedbyvolume

ratherthanbyaflatfee,regardlessoftheactualprices(Brandeset al.,2010;EuropeanEnvironmentAgency,2013).

However,notallvolumetricpricingschemesarecreatedequal,andtheycanleadtodifferentoutcomes.Differenttypesof

variablechargepricingstructurearesummarisedinTable4.2.

Table 4.2 Existing types of volumetric water use fee structure (adapted from Brandes et al., 2010).

Structure Description Comment

Uniformrate Priceperunitisconstantasconsumptionincreases

Targetsallusersequally;simpletocalculatebill

Incliningblockrate Priceincreasesinstepsasconsumptionincreases

Targetshighvolumeusers;requiresmorecomplexcalculatingforbilling

Decliningblockrate Pricedecreasesinstepsasconsumptionincreases

Chargeslowvolumeusersthehighestrate;typicallyusedwhereutilitieswanttoprovidelargeindustrywithalowercostofservice

Excessuserate Priceissignificantlyhigherforanyconsumptionaboveanestablishedthreshold

Canbeusedtotargethighconsumptionduringpeakperiods;moreeffectivewithfrequent(e.g.,bi-monthly)meterreading

Seasonalsurcharges Priceishigherduringpeakperiods(i.e.,summer)

Targetsseasonalpeakdemand;tiedtothehighermarginalcostsofwaterexperiencedduringpeakperiods

Zonalrates Userspayfortheactualcostofsupplyingwatertotheirconnection

Discouragesdifficult-to-serve,spatiallydiffusedconnections

Scarcityrates Priceperunitincreasesasavailablewatersupplydecreases(e.g.,duringdrought)

Sendsstrongpricesignalduringperiodsoflowwateravailability;analternativetooutdoorwateringrestrictions

Lifelineblock Afirstblockofwaterisprovidedatlowornocostbeyondthefixedchargetoensureeveryonehasaminimumamountofwatertomeetbasicwaterneeds

Usedtoaddressequityissuesandensurethatallconsumers’basicwaterneedsaremet


Incliningblockstructurestendtodiscourageexcessivewastageandunnecessarywaterusessuchaslawnwateringand

carwashing,butsomearguethatitisunfairtolargefamiliesandgoesagainsttheUNdeclarationofwaterasabasic

humanright,whichiswhylifelineblockstructureshavebeenimplementedinsomeareas(Brandeset al.,2010).However,

atthispoint,therestilldoesnotseemtobeanyonesinglefeestructurethatcansatisfyallconsumers.

Molinos-Senante(2014)proposesadynamicpricingstructurecombininganincliningblockrate(IBR)withadditional

peak-loadpricing(PLP)toconservewaterresourcesintheseasonswhenwaterismostscarce,preventexcessiveusein

thetourismsectorandobtainfullrecoveryofallcostsincurredintheacquisition,treatmentanddistributionofwater

services.Theauthorfeltthat,inadditiontomeetingthestatedgoals,thedualpricingsystemcouldcreatemoreequitable

distributionofcostsamongusersandreduceconsumptioninthetourismsector.

AsimilarincentiveprogrammewasimplementedincentralCalifornia,whereincliningblockpricingstructureswere

appliedtoanirrigationdistricttoreduceconsumption,aswellassalineinterflowtotheSanJoaquinRiver.Crop-specific

pricingtiersweresetonthebasisofpastdataofaverageirrigationdepth,andinformationwasmadereadilyavailableto

farmers.Theprogrammewaseffectiveinreducingirrigationdepth,andingeneral,supportofthepricingstructurewashigh

fromthoseinvolved,suggestingthatfarmersdorespondtoeconomicincentives(Wicheins,2006).

ColoradoSpringsUtilities(CSU)intheUnitedStatestookasimilarapproachbyintroducinganincliningblockrate

structurewithpriceincreaseseveryfiveyears(Figure4.2).Theyalsoofferedrebatesforimplementingconservation

measuresandinvestedinpubliceducation;aidingintheacceptanceoffeeincreases.Includedinthisweremedia

campaigns,communitymeetingsandcallcentrestoanswerquestionsorcomplaints.Withthecombinationofthesefactors,

theprogrammereducedconsumptionbyanaverageof13%,despitepopulationgrowth,andwasgenerallyacceptedbythe

public(WaterResearchFoundation,2015).

Figure 4.2 Colorado Springs Utilities (CSU) inclining block rate structure and fee increases (Water Research Foundation, 2015).

$0.12

$0.10

$0.08

$0.06

$0.04

Cubic Feet per Month

$0.02

2014

2009

2004

1999

$0.00

50 400

750

1,10

01,

450

1,80

02,

150

2,50

02,

850

3,20

03,

550

3,90

04,

250

4,60

04,

950

$ p

er C

ub

ic F

oo

t

4.2 WATER-SAVING TECHNOLOGIES

Water-savingtechnologiescanbeinstalledatmultiplescales,fromhouseholdstolargecommercialandindustrialbuildings,

andincludelowflowtoilets,faucetsandshowerheads,andwater-efficientwashingmachinesanddishwashers,etc.The

ideabehindimplementingthesetechnologiesistoallowuserstoconsumelesswaterwithoutalteringtheirlifestyles.

ThecityofAlbuquerqueintheUnitedStatesimplementedarebateprogrammeforwater-savingappliancesandpractices,

whichhelpedtosignificantlyreducewaterdemandinconjunctionwithsmallpriceincreasesandanawarenesscampaign.

Afterimplementationoftherebateprogramme–between1996and2009–totalwaterdemanddecreasedby16%(Price

et al.,2014).Furthermore,Priceet al.(2014)wereabletodeterminewhichwater-savingdevicehadthebiggestmarginal

impactonconsumption(Table4.3):low-flowtoiletshadthegreatesteffect,followedbyefficientwashingmachinesand

dishwashers.


Watersavingmethodsandtechnologiesalsohaveextensiveapplicationsinagriculture,andmayincludewater-saving

irrigation,limitedirrigationanddrylandcultivation.Respectively,thesemethodsuselesswaterwhileachievingthesameor

higheryield;inducedeficitsinthesoil-waterbalanceduringnon-criticalgrowthperiods,andthenirrigateduringessential

stages;andrelyontheefficientcaptureandusageofrainwaterinareasbeyondexistingirrigationnetworks(Denget al.,2006).

Specificmethodsofimprovingwateruseefficiency(WUE)includeselectiveirrigationtorestrictwateringtocriticalstages

ofplantgrowth,croprotation,intercropping,applicationofanimalmanurestoenhancesoilfertility,ormulching,which

decreasessoilevaporationandevapotranspiration,aswellasincreasesingrainyieldandWUE.Theapplicationofchemical

fertilisershasbeenshowntodoublegrainyieldsandthereforeWUE,althoughthiscancausechemicalloadingtowater

bodiesviarunoff(Denget al.,2006;Tischbeinet al.,2013).

ApaperbyDenget al.(2006)examinedthebestwater-savingirrigationmethods,manyofwhichusedharvested

rainwater.Amongtheseareroot-zonedripirrigationandunder-mulchirrigation.Toillustrate,traditionalpracticessuchas

furrowandbordermethodsusewateratarategreaterthan7,000m3perhectare,whereasdripirrigationusesjustover

3,000m3ofwaterperhectare,whileachievingthesameorsimilaryields.

Therealsoexistsavarietyofsmartsensingtechnologiestolimittheuseofwaterforgardeningandirrigationinparticular.

Someofthesetechnologiesincludethefollowing.

• WaterSenseirrigationcontrollers:devicesthatuselocalweatherforecaststodeterminewhenandhowmuchto

waterplants(UnitedStatesEnvironmentalProtectionAgency,2015).

• Soilmoisturesensors:sensorsplacedinthesoiltomeasurethesoilwatercontentandcontroltheirrigationsystem

accordingly(UnitedStatesEnvironmentalProtectionAgency,2015).

• Rainsensorsandshutoffdevices:thesedevicessensewhenitisrainingandshutoffirrigationsystems(United

StatesEnvironmentalProtectionAgency,2015).

4.3 WATER LOSS REDUCTION

Waterlossescanoccurateverystageofthewatercycle;extraction,treatment,distributionandusage,andcomprisereal

andapparentlosses.Theformerincludesleaksandpipebursts,whilethelatterincludesunauthorisedconsumptionand

customermeteringinaccuracies.These,inconjunctionwithauthorised,unbilledconsumptionmakeupnon-revenuewater

(NRW)(TrowandFarley,2006),theglobalannualvolumeofwhichisconservativelyestimatedat50billionm3(Liemberger,

2009).

IfutilitiescanreduceNRWthroughidentificationandappropriatebilling,thecostsavingsarepotentiallyhuge,allowing

utilitiestogreatlyincreasetheirincometocovertheadditionalrepair,replacementandmonitoringcosts.Thisalsoreduces

theneedtoinvestinadditionalinfrastructureortechnologiesforaugmentingthewatersupplybecausetheexistingsupply

willbeabletosatisfymoreofthepresentandfuturedemands(UnitedStatesEnvironmentalProtectionAgency,2013).

Waterlossreductioncanoftenbetheleastexpensiveandmosteffectivemethodofensuringtheadequacyofthewater

supply.Forexample,inthe1980s,UKutilityNorthWestWaterinvestedover200millionpoundsinaprojecttoaugment

Table 4.3 Change in water use due to specific water-saving devices, including low-flow toilets (LFT), water-efficient showerheads (SH), washing machines (WM) and dishwashers (DW), and xeriscaping (XS) (Price et al., 2014).

Change in water use (AWU) due to low-flow device.

Rebate AWU (%)

AWU (Gal/Dav)

Single device AWU (Gal/Dav)

Rebate value ($)

Device lifespan (vrs)

LFT1 −12.86 −37.98 −3798 200 25LFT2 −14.78 −46.87 −8.89(LFT2-LFT1) 400 25LFT3 −14.78 −60.36 −13.49(LFT3-LFT2) 600 25SH/LFT1 −16.26 −46.69 −8.71(SH/LFT1-LFT1) 210 10WM −3.32 −3043 −30.43 100 12DW −4.87 −17.84 −1784 50 10XS(100ft2) −0.84 −3.08 −3.08 75 25


supply,onlytoexperienceamere2%increaseinavailablewater.However,bycontrollingtheirleakage–whichaccounted

for35–40%ofthetotalwaterinthenetwork–theywereabletogreatlyincreasethesupplyofavailablewaterwithminimal

spending(Waldron,2001).Thissectionwillexplorethebestpracticesforensuringthatwaterlossiskepttoaminimum.

Leakmanagementhastwomaintypes,activeandpassive(reactive).Passiveleakagemanagementoccursinresponseto

incidentssuchaspipesburstingordropsinpressure.Activemanagementincludesleakagemonitoringandregular

surveyingofthewholedistributionsystem.Theactivemethodispreferable,asitresultsinfewerlosses,butsometimes

resourcesdonotallowforthiskindofstrategy.Whenassessingasystem’swaterlosses,awaterbalanceshouldbe

conductedtoindicatehowmuchwaterisbeinglostandwhereitcomesfrom.Table4.4showsthecomponentsofawater

balance,includingwaterlossesandNRW.However,methodsforcarryingoutawaterbalancevaryindifferentcountries,

makinginternationalcomparisonsdifficult(TrowandFarley,2006).

Table 4.4 Components of a water balance (Trow and Farley, 2006).

Sys

term

inpu

tvo

lum

e

(cor

rect

edfo

rkn

own

erro

rs)

Authorisedconsumption

Billedauthorisedconsumption

Billedmeteredconsumption(includingwaterexported)

Revenuewater

Billedun-meteredconsumption

Unbilledauthorisedconsumption

Unbilledmeteredconsumption Non-RevenueWater(NRW)Unbilledun-meteredconsumption

Waterlosses Apparentlosses UnauthorisedconsumptionCustomermeteringinaccuracies

Reallosses Leakageontransmissionand/ordistributionmainsLeakageandoverflowsatutility’sstoragetanksLeakageonserviceconnectionsuptopointof

customermetering

Tosolvethisproblem,IWAdevelopedaperformanceindicator(PI)calledtheinfrastructureleakageindex(ILI),toallow

internationalcomparisonsofreallosses.TheILIusesseveralparameters,includingtheconditionofthefacility’s

infrastructure,leakage,andpressuremanagementandleakrepairprogrammes(TrowandFarley,2006).TocalculateILI,the

currentannualreallossesaredividedbytheunavoidableannualreallosses(UARL),whichisthesmallestamountofwater

thatcanbelostfromanefficient,well-maintainedsystem.TheadoptionoftheILIbyutilitiesaroundtheworldisanindicator

bothforitsaccuracyandapplicabilityasaninternationalstandard.AnILIvaluelowerthan2meansthatthecurrentreal

lossesarelessthantwicetheunavoidablelosses;systemswithsuchILIvaluesaregenerallyconsideredtobeavery

efficient(Delgado,2008).

Figure 4.3 Four pillars of leakage management (Trow and Farley, 2004).

PressureManagement

Annual Volumeof Losses fromLeakage and

Overflows

Speed andQuality of Repairs

Active LeakageControl

InfrastructureManagement


IWAalsodevelopedfourmainpillarsofleakagemanagement(Figure4.3).Thepillarsincludepressuremanagement,

speedandqualityofrepairs,infrastructuremanagementandactiveleakagecontrol,eachofwhichhavediminishingmarginal

returnsinreducingthevolumeoflossesandleakage(TrowandFarley,2004).

Perhapsthemostimportantofthesefourpillarsispressuremanagement,asmorewatercanbequicklysavedthrough

thismethodthananyother.Controllingpressureindistributionsystemscanbeextremelyefficientatreducingleakage,and

dosoatalowcost;mostpressuremanagementprogrammeshavepaybackperiodsoflessthantwoyears.Typesof

pressurecontrolincludeflow-modulatedcontrol,time-controlandfixed-outletcontrol,andthebestmethodtouseis

dependentonthesupplysysteminquestionandthefundsavailable.Astrongexampleoflargescalewaterlossreduction

withpressuremanagementistheKhayelitshainstallationinSouthAfrica,theimplementationofwhichresultedinannual

watersavingsof9millionm3;a40%decreaseinaveragedailyflow(7thWorldWaterForum,2015).

Itshouldbenotedthatdirectcomparisonscannotalwaysbemadebetweenpercentagesofwaterlossreduction.

Consumptionofwatercanvaryenormouslyowingtotheweather,makingapercentageleakagerateappeartodoubleor

halfduringextensiveperiodsofrainordroughts.Watersupplysystemscarryinherentdifferencesinsize,demandand

complexity;twoutilitiesexpressingthesamepercentreductioninlossesmayhavehadvaryinglevelsofsuccess.Therefore,

caremustbetakenwhenusingpercentagesforsuchcomparisons,anditiswisetoalsohaveanalternativefigureto

compare,suchaslitresperpropertyperhour,litresperlengthofwatermains,andideallyshowingtheILIvalue.

Theexistenceofwaterlossescanbeprovedwithacombinationofsmartmetering,districtmeteringandbulkmetering

systems.Integratingthesedataallowsutilitiestoquantifyleakagewithrelativeaccuracyandanalysenightflowratesto

improvewaterlossreductionstrategies.Loureiroet al.(2014)achievedthisbyusingselectdistrictmeteredareas(DMAs)

ascasestudiesandcollectinghourlycustomerdatafrommeters,thenusingalgorithmstodeterminewhichcomponents

wereapparentlosses,assumingthatreallossesstayedfairlyconstant.Theywerealsoabletodetectpipeburstsandillegal

waterusethisway(Figure4.4).Usingthecollecteddatatoimprovetheirunderstanding,theauthorswereabletomake

targetedeffortstoreducelossesbyanaverageof10%inthestudiedDMAs.

Figure 4.4 Flow profiles of a chosen DMA, modelled to detect illegal water use and pipe bursts (reprinted from Water Science & Technology: Water Supply 14 (4), 618–625 (2014) with permission from the copyright holders, IWA Publishing).

8.0(a)

7.0

6.0

5.0

4.0

3.0

Flo

w (

m3 /h

)

2.0

1.0

0.03-Dec 5-Dec 7-Dec

DateTotal inflowNon-revenue waterReported leaks and bursts

Total metered consumptionReal lossesApparent Losses

Total inflowNon-revenue waterReported leaks and bursts

Total metered consumptionReal lossesApparent Losses

Reported pipe burst

9-Dec 11-Dec

9.08.0

(b)

7.06.05.04.03.0F

low

(m

3 /h)

2.01.00.0

5-Jan 7-Jan 9-JanDate

Illegal water use

11-Jan 13-Jan 15-Jan

Apromisingtechnologyformonitoringandreducingreallossesinwaterdistributionsystemsistheimplementationof

automaticmeterreadingforservicepipes,whichautomaticallycollectsconsumptiondataandtransfersittoacentral

database,eliminatingtheneedtomanuallycheckmeters,whichcanbetime-consumingandleadtomorewastage.

automaticmeterreadingmayalsoallowformoreaccuratedetectionofleaksthatmaynototherwisehavebeenfound,as

wellaspreciseestimationsofleakagefromnight-timeflows.Thecommonpracticeofestimatingnight-timeleakagehas

beenthesubjectofcriticism,withsomeexpertsstatingthatitlacksaccuracy.Theprovisionofharddataandaccurate

minimumnightflow(MNF)valuestoutilitiesisinvaluableincalculatinglosses,detectingleaksandcreatinggreater

efficiencyinsystems(Waldron,2007).

InastudybyMunet al.(2008),acomprehensivewaterlossmanagementstrategywasimplementedinKorea,inacity

withhighratesofwaterlossduetopoormanagement,old,dilapidatedpipes,andarevenuewaterratioofonly55%.The

mainmethodsadoptedtoreducewaterlosswerethefollowing:

1. introductionofablockzoningsystem;

2. piperehabilitation/replacement;

3. pressurecontrol.


Thezoningsystem–inwhichthewholeserviceareaisdividedinlargeblocks,thenagainintomediumandsmaller

blocks–helpstomakethesystemeasiertomonitorandmaintain.Eachblockismonitoredforpressureaswellaswater

qualityandquantity,andleakscanbemoreeasilyidentifiedandrepaired.Italsoprovidesanadditionalelementofcontrolin

emergencies,asproblemlocationscanbeisolated.Thesecondmethodusedinthemanagementstrategywaspipe

rehabilitationandreplacement.50kmofpipe,aswellasallwatermetersandvalveswerereplacedowingtoleaks,

blockageorcorrosion.

ThethirdandmostcriticalelementoftheKoreancasestudywaspressurecontrol,inwhichvalveswereinstalled

accordingtotherangeofinitialpressuretohavemaximalefficacy.Munet al.(2008)isolatedtheeffectsofpressurecontrol,

andfoundthatthisstepaloneledtoa25%decreaseinwaterproductionanda10%increaseintherevenuewaterratio.

Figure4.5showstheeffectoftheentireprogrammeovera2-yearperiodontherevenuewaterratio,whichincreasedfrom

55%to70%between2004and2006.

Figure 4.5 Production, consumption and revenue water ratio in the study location of Mun et al. (2008) from the beginning of 2004 to the end of 2006 (reprinted from Water Practice & Technology 3 (2), 1–7 (2008) with permission from the copyright holders, IWA Publishing).

1,600,000

1,400,000

1,200,000

1,000,000

800,000

600,000

400,000

200,000

2004

-1 3 5 7 9 11

2005

-1 3 5 7 9 11

2006

-1 3 5 7 9–

Pro

du

ctio

n &

Co

nsu

mti

on

(m

3 /day

) 80productionconsumptionrevenued water ratio 70

60

50

40

30

20

10

0

Rev

enu

ed w

ater

rat

ion

(%

)Itisimportanttoconsidersocio-economicfactorswhencreatingstrategies,aslow-andmiddle-incomecountriesaccount

forabout70%oftotalwaterlossesworldwide.AccordingtoLiemberger(2009),SouthandSoutheastAsiahavesomeof

thehighestratesofwaterlossintheworld.InIndiaespecially,mostwaterutilitiesexperienceintermittentsupply,sometimes

foronly3–5hourseveryfewdays.Evenwiththislackofcontinuoussupply,waterlossratesareextremelyhighowingto

poormaintenanceanddegradedinfrastructure.Therefore,evenifsupplyweretobecomecontinuous,NRWwouldbeso

highthatthetotalsupplywouldnotbeimproved.

Anotherfactoratplayisthetypeofwaterlosstakingplaceandinwhatproportion.Someutilitieshavehighervolumesof

unbilledcommerciallossesduetocorruption,theftorpoormetering,thanphysicallossesduetoleakage,andviceversa.

Waterlossreductionstrategiesshouldincludeinvestmentininfrastructurerepairandmaintenance,aswellasmeter

installationandincentivestoreducetheftandunbilledconsumption.Therealsoexistsalackofdataonwaterlosses,

especiallyindevelopingcountries,andthereforedatacollectionshouldbethefirstcourseofactionindevelopinga

managementstrategy(Liemberger,2009).

Unfortunately,methodsofreducingwaterlossescanbeveryexpensive,sometimesprohibitivelyso.Itisnotuncommon

forgovernmentsandutilitiestoinvestminimallyinageinginfrastructure:ashort-sightedapproachthatleadstogreatercosts

inthefuture.AprominentexampleofthisisMontreal,Canada,whichloses40%ofwaterinthesupplysystemeveryyear

becauseofdilapidatedinfrastructure.Athirdofthecity’swaterpipeshavealreadyreachedtheendoftheirusefullifespan,

andtheothertwo-thirdsarepredictedtoreachthispointwithinthenext20years(FraserInstitute,2010).Despitethepoor

stateofMontreal’swatersystem,thecityhasyettoimplementthestepsnecessarytochangeitbecauseofthe4 billion

Canadian dollar investmentthatwouldberequiredtoupgradeinfrastructure(FraserInstitute,2010).Further

exacerbatingtheissueisthelackofinstalledmetersandtheflatfeepricingstructure,subsequentlycreatingalackof

revenueforwaterutilities.Implementingpricingstructuresthataccuratelyreflectthecostofproductionmaybeastepinthe

rightdirectionintermsofreducingwaterlosses,butwouldprobablybemetwithdisapprovalfromresidentswhohave

grownaccustomedtopayingthecurrentrates.


Ingeneral,water-lossreductionstrategiesmust

• betailoredtothespecificlocationofthewatersupplysystem;

• bewellintegratedintosurroundingsystems;

• beforward-thinkingwithawillingnesstoinvestinlong-termsustainability;

• takeintoaccounttheeconomic,social,politicalandenvironmentalfactorsofanarea.

Bytakingthesesteps,moreholisticandeffectivewater-lossreductionstrategiescanbeachieved(SchoutenandHalim,

2010).

4.4 OPERATIONAL EFFICIENCY

Operationalefficiencyreferstotheoutputtoinputratioofwatertreatmentprocesses,andanimportantpillarofwater

managementisthedevelopmentofstrategiesortechnologiesthatwillenhancethisefficiency.Thiscaninclude

implementingtechnologiesthatemitfewerwasteproducts,formingpartnershipstocreateeconomiesofscaleoragreater

rangeofexpertise,andimprovingsupervisorycontrolanddataacquisitionofwatersupplysystems.Onewayofensuring

betteroperationalefficiencyistheuseofpropercleaningandmaintenanceoftreatmentsystems.Toofrequentcleaningcan

resultinunnecessarywastage,whereasinfrequentcleaningresultsinpoorperformanceandclogging.Monitoringeffluent

turbidityorhydraulicheadlossandthencleaningwhennecessaryallowssystemstoperformoptimallywithoutwasting

resourcesonover-cleaning.Airscoursystemsandair/waterbackwashsystemsarebothefficienttechnologiesforcleaning

filtrationsystems(UnitedStatesEnvironmentalProtectionAgency,2013).

Operationalefficiencycanalsobeenhancedthroughimprovedstoragecapacity.Issuesoftenarisebecauseof

discrepanciesinwaterneedsbetweenseasons,forexample,periodsofhighestrainfallalsotendtobeperiodswiththe

leastwaterdemand,andviceversa.Withconventionalabove-groundstoragemethodssuchastanksandreservoirs,

overflow,contaminationanddiminishedqualityovertimearepotentialproblems.Aquiferstorageandrecovery(ASR)–

inwhichtreatedwaterisintroducedtoaquifersforstorageuntillateruse–isawayofovercomingthiswhilemaintaining

thewatertable,reducingtheriskofcontaminationandensuringadequatewatersupplyintimesofhighdemandor

supplyinterruption(Niaziet al.,2014).ASRespeciallyimprovesoperationalefficiencyfordesalinationandwaterreuse

becauseitallowsforsteadyenergyuse,removingtheneedforlargevariationsthatcanresultinwastage(Ghaffouret al.,2013).

4.5 EDUCATION AND AWARENESS

Educationandawarenessofenvironmentalandwaterscarcityissuescanbepowerfultoolsinreducingwaterdemand.

Examplesofthisincludeschool-levelwaterconservationprogrammes,radioandTVmessagesandinformationinmail-outs,

workshopsornewspaperadvertisements.Thisisamechanismthat,evenifitdoesnotcreatepermanentdemandreductions

onitsown,canbeincorporatedfairlyeasilyintoanydemandmanagementstrategywithverylittledownside.

Fieldinget al.(2013)performedanexperimentalstudytotesttheeffectsofvariouseducation-basedinterventionson

householdwaterdemandinAustralia.Theaveragedailywateruseforallgroupsdecreasedduringandimmediatelyafterthe

interventionperiod.Unfortunately,allgroupsreturnedtopre-interventionlevelsofwateruseby12monthsafterthe

interventionsceased,suggestinganeedforadditionalmeasures.Fanet al.(2014)alsostatethatifusersdonothave

accurateperceptionsoftheirownwateruse,educationcampaignsandotherdemandmanagementstrategiesmaybeless

effective,andthereforeawarenesscampaignsthatallowconsumerstorealisetheirownconsumptionpatternsarelikelyto

bemoresuccessful.

Watermeteringisanindirectdemandmanagementtoolthatmayhelptoenhanceawarenessofwateruse.Watermeters

allowtheexistenceofleakstobeproved,andenableutilitiestoimplementperunit,volumetricpricingstructures,which

incentivisemoreconservativewateruse(seesection4.1).Finally,whenaconsumercanseehowmuchwaterisbeingused,

theincreasedawarenessmaypromotemoresustainableconsumptionpatterns(Bealet al.,2011).Studieshaveshownthat

theinstallationofwatermetersleadstowatersavingsofbetween10and30%,andcanbeashighas50%(Biswaset al.,2009).


4.6 COMBINED DEMAND MANAGEMENT SOLUTIONS

Somedemandmanagementmechanismsarestrongerthanothers,andadditionalbenefitscangenerallybeaccruedby

combiningseveralstrategiesinonejurisdictionalarea.Table4.5comparesthedemandmanagementstrategiesofvarious

locations,andtheaveragereductionsinwaterdemandthatwereachieved.

Table 4.5 Comparison of different demand management case studies and their associated water use reduction.

Location Pricing Metering Water saving

devices/methods

Water loss reduction

Education & awareness

Legislation Average Reduction

Study

Canada ● ● 43% Brandeset al.(2010)

NewMexico,USA

● 16% Priceet al.(2014)

China ● 56% Denget al.(2006)

SouthAfrica ● ● ● ● ~42% Buckle(2004)India ● ● ● 8-20% Biswaset al.

(2009)Australia ● 6-15% Fieldinget al.

(2013)Colorado,

USA● ● ● ● 13% WaterResearch

Foundation(2015)

Portugal ● ● 10% Loureiroet al.(2014)

SouthKorea ● 25% Munet al.(2008)

Guelph,Canada

● ● ● 18% CityofGuelph(2013)

Windhoek,Namibia

● ● ● ● 35% SharmaandVairavamoorthy(2009)

Someotherexamplesofcountrieswhichmanagedemandeffectivelyarethefollowing.

• Singapore,whoseNRWexpressedaspercentageofsysteminputvolumeislessthan10%.Theyuseeconomic

incentives,comprehensiveeducationprogrammesandconservationmeasurestoreducedemandforwaterresources

(SharmaandVairavamoorthy,2009).

• TheUK,whoseleakreductionprogrammesmanagedtoreduceleakagebycloseto30%between1994and2009.

Also,promotionofwater-savinghouseholddevices,alongwithawarenesscampaigns,haskeptpercapita

consumptionrelativelylow(SharmaandVairavamoorthy,2009).

• SouthAfrica,whoseactiveleakagecontrolprogrammeandretrofittingofpublicanddomesticbuildingshasreduced

waterdemand(SharmaandVairavamoorthy,2009).

• France,wheretheprovinceofBrittanyusededucationcampaigns,letterstoresidents,leakagemonitoringand

water-savingdevicestocontrolwaterdemandbothinpublicandinprivatesystems,achievingwatersavingsof

between14and79%,dependingontheuser(SharmaandVairavamoorthy,2009).

Unfortunately,developingcountriesaregenerallylesswellsuitedtobenefitfromdemandmanagementstrategiesbecauseof

lowerincome,dilapidatedinfrastructure,reducedelasticityofdemandforwaterandlowerinstitutionalcapacity.

Animportantconceptintheintegrationofdemandmanagementsolutionsisthatofdifferentordersofscarcity.Thefirstof

theseisphysicalscarcity,inwhichthereisphysicallynotenoughfreshwatertomeettheneedsofthepopulation.Second-


orderscarcityreferstoscenariosinwhichthewatersupplyisnotphysicallyscarce,butcontamination,poormanagementor

inefficientusemakesasignificantquantityoftheresourceunusable;thisistechnologicalorinstitutionalscarcity.Third-order

scarcityreferstothesocial,politicalandculturaldimensionsofwaterscarcity;theperceivedabundanceofwaterleadingto

overuseorhabitualhigh-consumptionlifestyles.Justasthesethreeordersofscarcityaredifferent,sotooaretheirpotential

policyresponses,listedinTable4.6(WolfeandBrooks,2003).

Table 4.6 Overview of the three orders of scarcity, the dominant disciplines applicable to them and their response options (adapted from Wolfe and Brooks, 2003).

Order of scarcity Dominant discipline Responses

First Engineering Supply-sideprojects(dams,pipelines,canals,wells,desalination)

Second Economics Demand-sidemanagement;waterasaneconomicgood;technicalfixes

Third Socialscienceswithinbiophysicallimitations

Newoptionsandreallocation,technologicalchange,‘water-soft’paths

Thegoalofthird-orderscarcityresponsesistoshiftsocietalnormsawayfromhighconsumptionlifestylesandmake

conservationpracticesstandard.Thisreallocationofresourcesinfavourofconservationiscalleda‘watersoftpath’,the

implementationofwhichisbecomingmorepopularinresourcesmanagement.Thesepracticescanbedifficulttoimplement,

butnaturallycurbdemandandincreasethesustainabilityofwateruse,andshouldbeintegratedwithpoliciesaddressing

first-orsecond-orderscarcitywhereneeded(WolfeandBrooks,2003).


5 TOWARDS RELIABLE AND SUSTAINABLE WATER SUPPLY SYSTEMSThereisagrowingneedforreliableandresilientwatersuppliesthatusethehighestefficiencyuseofalternativeand

conventionalwatersourcesinconjunctionwithminimisedenergyuse.

Infinancialsectors,a“portfolio”managementconceptisused,whichaimstomitigateriskbyspreadingitbetween

severaldifferentresourceoptions(PaydarandQureshi,2012).Inthecaseofwatermanagement,asimilarconceptofthe

“portfolio”approachcouldbeconsidered,whichmeansutilisingwaterfromavarietyofdifferentsources–someofwhich

shouldbehydrologicallyindependent–tocreateamorerobustsupply.Acomprehensiveunderstandingofboth

hydrologicalandeconomicconceptsiscrucialwhenusingthiskindofapproach.Portfolio-basedwatermanagement

projectsshouldaimnotonlytoeffectivelymanagethewatersupplybutalsotoincreaseenvironmentalsustainability,use

energyefficientlyandyieldsocialbenefits.

Theportfolioapproachbearssomeresemblancetointegratedwaterresourcesmanagement(IWRM),butthetwoarenot

oneandthesame.IWRMcoversabroaderformofwatermanagementthat“promotesthecoordinateddevelopmentand

managementofwater,landandrelatedresourcestomaximiseeconomicandsocialwelfareinanequitablemannerwithout

compromisingthesustainabilityofvitalecosystems”(GlobalWaterPartnership,2012).Whilethismayincludeusinga

portfolioapproach,itisnotmandatory,asIWRMplansmayfocusonasinglewatersourcewithinthescopeofitsmain

principles.

RegardlessofwhetherornotapproachestowatermanagementarecategorisedunderportfoliomanagementorIWRM,

theyshouldaimtocreatemorereliableandsustainablewatersupplysystems.

5.1 CONSIDERATIONS AND EXAMPLES

EachpotentialAWRcarrieschallenges,andwiththosechallenges,possiblesolutions(Figure5.1).Itshouldbenotedthat

lakes,rivers,reservoirsandgroundwatercanalsobetreatedas“alternative”waterresources,butFigure5.1aimsto

summarisetheresourceoptionsdiscussedinChapters2–4.Watertrading/transfersmayalsobenecessaryinsomeparts

oftheworld,particularlyinthecaseofdroughts,disastersorotherextremeevents,butthesearenotincludedinthescope

ofthispaper.TherearemanymorepotentialproblemsandsolutionsinherentinAWRthanaredepictedinFigure5.1,but,

tosimplifythevisualrepresentation,onlymoreprevalentconcernswereincluded.

Thepresenceofthesechallengesinherentineachwatersupplyoptionmakesdiversifyingwatersuppliesevenmore

crucial.Combiningmultipleoptionscreatesredundanciesinthesystem,reducingtheriskofhavinginsufficientfreshwater

suppliesorissuesofpublichealth.

Themonetaryandenergycostsofallpossibilitiesshouldalsobeconsidered,toassessthefeasibilityofcertainoptions

againsttheavailablefundsandenergysources;thenavariedportfoliocanbebuiltoutoftheseoptions.Table5.1provides

ageneralisedcomparisonoftheaveragemonetaryandenergycostsofseveralwaterresourceoptionsusedworldwide.

Figure5.2depictsavisualrepresentationofthesameinformation.

ChinaandotherAsiancountrieshavebegunusingAWRinanintegratedapproach,andhaveseenimprovementsin

socio-economicconditions,environmentalhealthandwaterscarcityfactors.Wanget al.(2014)modelledthreepotential

futurescenariosfortheTongzhoudistrictinChina–business-as-usual,planning-orientedandsustainabledevelopment–to

predicttheireffectsonlocalindustry,GDPandwaterscarcity.Thefirsttwoscenariosusedonlygroundwaterandsurface

watertomeetdemand,whereasthesustainabledevelopmentscenariomethalfofitsdemandwithreclaimedwaterand

incorporatedwatertransfersaswell.Underthebusiness-as-usualscenario,thetotalwaterdemandin2020waspredicted

tobeabout366millionm3,whileinthesustainabledevelopmentscenarioitwas375millionm3.However,eventhoughthis

scenario’stotalwaterdemandwasslightlyhigher,itmetalmosthalfofitsdemandwithreclaimedwater,andexperienced

thegreatestGDPincreasesduetoastrengthenedtertiarysector,andmoreefficientwateruseintheprimarysector.

Californiaisaprominentexampleofawaterportfoliothatiscurrentlybeingexpandedtorespondtoscarcity.In2015,

Californiaimplementedmandatoryusagecutsof25%below2013levelstoutilitiesaftervoluntaryreductiontargetsin2014

werenotmet(BluefieldResearch,2015).Asoftheendof2014,45regionsinthestatehadimplementedcomprehensive

integratedwaterresourcesmanagement(IWRM)plans,withmoreplanned(CaliforniaDepartmentofWaterResources,

2015).InJanuary2015,overUS$850millionwasallocatedtoplannedandcurrentwaterreuseanddesalinationprojectsto

shiftdemandawayfromsurfaceandgroundwatersupplies.Whilereuseanddesalinationhavebeenslowtotakeholdin

Californiabecauseofhighcostsandcommunityopposition,droughtpressurehasincreasedthemarketpotentialandpublic

acceptanceofbothsources(BluefieldResearch,2015).


Figu

re 5

.1 Sim

ple ‘m

ind m

ap’ d

epict

ing A

WR

optio

ns (b

lue),

som

e ge

nera

l cha

lleng

es (g

reen

) ass

ociat

ed w

ith e

ach

cate

gory

and

pot

entia

l solu

tions

(pur

ple).


Table 5.1 Comparison of the average per unit costs and energy requirements of acquiring groundwater, surface water and several AWR options.

Resource option Average Electrical energy equivalent per m3

Average Cost per m3 Source(s)

Surface water ~0.36kWh(Worldwide) US$0.0003–0.40(Asia)

Gudeet al. (2010);Zhuet al.(N.D.)

Groundwater 0.14–0.24kWh(Worldwide)

US$0.05–0.07(Asia) Gudeet al.(2010);Zhuet al.(N.D.)

Brackish water RO 1.22–1.62kWh(NorthAmerica)

US$0.26–1.05(NorthAmerica,Europe)

Gudeet al.(2010);RaucherandTchobanoglous(2014);KaragiannisandSoldato(2008)

Seawater RO 2.0–4.5kWh(Worldwide) US$0.75–1.89(NorthAmerica)

Gudeet al.(2010);WateReuseAssociation(2012);RaucherandTchobanoglous(2014);Cornejoet al.(2014);Macharg(2011)

MSF desalination 13.5–25kWh(Worldwide) US$0.80–2.00(Australia)

Gudeet al.(2010);Wittholzet al.(2008);Cornejoet al.(2014)

Potable euse 0.84–0.92kWh(NorthAmerica)

US$0.66–1.62(NorthAmerica,Africa)

RaucherandTchobanoglous(2014);LahnsteinerandLempert(2007)

Non-potable reuse 0.27–0.42kWh(NorthAmerica)

US$0.25–1.59(NorthAmerica)

RaucherandTchobanoglous(2014)

Rainwater harvesting 0–0.1kWh(Worldwide) US$0–0.20(Vietnam,Tanzania)

Kimet al.(underreview)

Figure 5.2 Unit cost and energy consumption for various AWR (provided by Mooyoung Han).

25

24.8

13.6

13.4

4.6

4.4

4.2

2

2

1.8

1.8

1.6

1.6

1.4

1.4

1.2

1.2

1

1

0.8

0.8

0.6

0.6

0.4

0.4

0.2

0.20

0

Ene

rgy

requ

irem

ent p

er m

3 (K

Wh)

Cost per m3 (USD)

Groundwater

Surfacewater Rainwater

Potable Reuse

Non-Potable Reuse

Brackish water RO

MSF desalination (13.5~25KWh)

Seawater RO (2~4.5KWh)


5.2 INFLUENCING FACTORS IN WATER SUPPLY SYSTEMS

Tocreateintegratedsolutionstoissuesofwaterscarcityandresourceuse,allrelevantfactorsmustbetakenintoaccount,

includingenvironmental,social,economicandpolitical/institutionalaspects.Acentralgoalofsustainablewatermanagement

istoreducethelikelihoodofscarcity,soitmustincludeday-to-daywateruseprovisions,aswellascontingencyplanningfor

droughts.

5.2.1 ENVIRONMENTAL FACTORS

Environmentalaspectsinfluencingwaterportfoliodecisionsmaybedifficulttoidentify,quantifyandmanage.Factorssuch

asgreenhousegasemissions,effluentdischarge,ecosystemfragility,biodiversity,waterpollution,salinisationofaquifersand

manyotherrelatedissuesmustbeconsidered.

Toensurethatminimalenvironmentaldamageoccurs,acomprehensiveenvironmentalimpactassessment(EIA)mustbe

completedtoassessallpossiblelocations,scalesandtechnologies,takingintoaccountwaterdemandandenvironmental

factors.Withthisinformation,partiescandeterminetheoperationalproceduresthatwillbestalleviatetherelevantregion-

specificwaterconcerns.Projectsmustalsobeperformedwithproperaccountingoftheenergyrequirementstoseehow

thesefallinwithnational(orinternational)commitmentstoenergyandemissionsproduction,orotherenvironmental

agreements,aswellasathoroughunderstandingandintegrationofthewater–energynexus(Schreineret al.,2014).

5.2.2 SOCIAL FACTORS

Socialfactorsaffectingwaterusemaybeoverlookedinfavourofeconomicfactors,buttheyareextremelyimportant.First

andforemost,decisionmakersmustrememberthatcleanwaterisabasichumanright,asdesignatedbytheUnited

Nations,andthiscannotbeignored(UnitedNations,2014).Alleffortsmustbemadetomakewaterfordrinkingand

sanitationavailabletoallpeople.Theethicaldimensionsofwatermanagementextendalsototheroleofwomen,whoin

manycountriesarethemainusersofdomesticwater,aremoresusceptibletowaterbornediseasesthanmen,andmust

fetchwaterfortheirhouseholds(UnitedNations,2005).Inregionswherewomenaremoreheavilyaffectedbywater

managementdecisions,theiropinions,ideasandwelfareshouldbeofcentralfocus.

Anotherimportantdimensionofthesocialfactorsofwaterportfoliosistheexistenceofsocialnormsaffectinglocal

behaviour.Inmanydevelopedcountries,the“mythofabundance”–whichleadspeopletobelievethatthereexistmorethan

sufficientnaturalresourcestosatisfyhumanneeds–isdeeplyrootedintheprevailingmindset,reducingthelikelihoodthat

themajorityofpeoplewillengageincertainconservationbehaviours.Societiesinwhichchildrenhavebeenraisedto

understandthatwaterisascarceresourcethatmustbeconservedaremorelikelytohavelowpercapitawaterdemands

andtorespondtodemandmanagementstrategies.Theseattitudesalsohaveasignificanteffectonwhetherornotwater

reusecanbeimplemented,sincewithoutpublicacceptance,suchprojectsareunlikelytobesuccessful.However,these

attitudesareunlikelytochangequickly,andmaytaketimetobeeffective.

5.2.3 ECONOMIC FACTORS

Economicfactorsareoftenastrongconsiderationfordecision-makerswhenmanagingthewatersupply,asfinancescanbe

ahighlylimitingfactor,particularlyintheearlystagesofaproject,whenpotentialeconomicbenefitshavenotyetbeen

accrued.Therefore,thesefactorsmayoftendeterminewhetheraprojectcanbeimplemented.

Beforeaprojectcanbeimplemented,acomprehensivecost–benefitanalysis(CBA)mustbecompleted.TheCBAmust

takeintoaccountboththecapitalandoperationalcostsofthedevelopment,thepotentialeconomicbenefitssuchasjob

creation,environmentalimprovement,reductionsinwateracquisitioncostsfromothersources,andastrategiclife-cycle

assessment(LCA)oftheproposedprojectagainstotherpotentialwatersupplyoptions(Schreineret al.,2014).Perhapsthe

mostdifficultaspectofassessingthecostsandbenefitsofwatersupplyprojectsistheactofenvironmentalvaluation,

whichcanbehighlysubjective.Valuingecosystemservicesandrecreationalusesoftheenvironmentoftenrequireindirect

valuationmethodsanddiscountingonfuturevalues,andmaynottakeintoaccountpositiveandnegativeexternalities.

Therefore,thesecalculationsmustbedonecarefully,andassignappropriatevaluetonaturalenvironmentalentities.


5.2.4 POLITICAL/INSTITUTIONAL FACTORS

Goodgovernanceandpolicystronglysupporttheimplementationofgoodwatermanagement,butlegalandinstitutional

constraintstoportfoliomanagementmustbeaddressed.Legislativeprocessesmaybelengthy,withmultiplestepsinvolved,

whichcaninhibitapprovalofAWR-basedprojects.Theseprojectscanalsofailbecauseofstringentguidelinesregarding

waterreuseorothersimilarprocesses.Therefore,whenchoosingwatersupplyoptions,thelocalguidelinesmustbekeptin

mindsothattimeandfundsarenotwastedonprojectsthatwillprobablyberejected.

Fromagovernment’spointofview,agenciesshouldaimforprocessesandlegislationsthatsupportlong-term

sustainability,buildcapacityforfuturegrowthandencourageengagementofawiderangeofstakeholders.Bytakinginto

accounttheneedsandvaluesofallinterestedparties,governmentscanaidinthecreationofmoreholisticwaterportfolios

whilesimultaneouslygainingsupportfromthepublic.

Thedevelopmentofrelevantpolicyincentivestoensuretheintegrity,sustainabilityandregulatorycomplianceofall

phasesofprojectimplementationiscrucial(Schreineret al.,2014).AshasbeenmentionedearlierinthisCompendium,

peoplerespondtomonetaryincentives,andifindividualsorgroupsaremotivatedtocomplywithhealthandsafety

guidelinesanduseenvironmentallyfriendlypractices,thesafetyandreliabilityofwaterportfolioscanbesafeguarded.


6 SHOWCASE OF AWR TECHNOLOGY

6.1 HONG KONG INTERNATIONAL AIRPORT

HongKongInternationalAirport(HKIA)–assessedinapaperbyLeunget al.(2012)–successfullyimplementedatriple

watersupply(TWS)systemthatincludesafreshwatersupplyforpotableuses,aseawatersupplytobeusedintoilet

flushingandairconditioning,anirrigationsystemusingreclaimedgreywater,andseparatecollectionsystemsforgreywater

andblackwater(Figure6.1).TheHKIAusesapproximately9,000m3perdayoffreshwaterforuseinfoodservices,aircraft

washing,andbathroomsinks.Ofthis,approximately4,000m3isreclaimedasgreywaterandusedforgardenirrigation

surroundingtheairport.

Figure 6.1 HKIA triple water supply (TWS) system (reprinted from Water Science & Technology 65 (3), 410–417 (2012) with permission from the copyright holders, IWA Publishing).

ThroughtheimplementationoftheTWSsystem,theHKIAhasbeenabletoreducetheirwaterdemandby52%.Ofthis,

41%isfromflushingtoiletswithseawater,4%isfromgreywaterreuse,andtheother7%isattainedbyplantingdrought-

tolerantgrassesandthusminimisingirrigationneeds(Leunget al.,2012).Thesystemalsoprovidesbenefitsintheform

ofenergysavings,mostlybecauseoftheminimaltreatmentneededtouseseawaterfortoiletflushingasopposedto

greywater.Table6.1showstheestimatedenergy,costandemissionsassociatedwithtreatingseawater,freshwaterand

reclaimedwaterfortheirrespectiveenduses.AccordingtothestudyofLeunget al.(2012),substitutingseawaterfor

reclaimedwatercansaveUS$240,000,1,600tonnesofCO2emissionsand2,800MWhofelectricityperannum.

Table 6.1 Energy consumption, electricity cost and emissions associated with treating three types of water for their desired end uses (reprinted from Water Science & Technology 65 (3), 410–417 (2012) with permission from the copyright holders, IWA Publishing).

seawater for toilet flushinga Freshwater 1 supplyb Reclaimed waterc

Energyconsumption(kWh/m3) 0.013–0.025 0.05 0.2–1

Comparison based on Airport Isle 7,600 m3/day: Island’s TWS system with flushingseawater flow of 7,600m3/day:Electricitycostd(US$thousand/year) 3.1–6.0 12 48–240Energyconsumption(MWh/year) 36–69 140 560–2,800CO2emissione(tonne/year) 21–40 80 320–1,600

ThereducedtreatmentcostsarenottheonlymonetarybenefitsassociatedwiththeTWSsystem.Althoughthecapital

costofimplementingthesystemwasaboutUS$70million–includingtreatmentplants,upgradeddistributionsystems,

seawatercoolingandtoiletflushingsystems–savingsperyearhasaveragedUS$3.8million,reducingthepaybackperiod

tolessthan20years.Includedinthesecostsavingsarethereductionsinelectricitycosts,freshwaterpurchased,and

sewageandtradeeffluentcharges(Leunget al.,2012).


AlthoughsomeissueswiththeTWSsystemwereencounteredearlyon–particularlywithrespecttoseawatertoilet

flushing–thereplacementofuPVCpipeswithpolyethylenepiping,upgradingthematerialusedfortheflushingvalvesand

changingtheshapeofthetoiletbowlstomakethemmoreconducivetocleaningandmaintenancemadethesystem

functionmoreoptimally(Leunget al.,2012).OwingtothesuccessoftheTWSsystematHKIA,similarsystemsmaybe

feasibleforimplementationaroundtheworld,particularlyinlow-incomeandfreshwater-scarcecountrieswhereseawater

desalinationisprohibitivelyexpensive.

6.2 PERTH, AUSTRALIA: RO DESALINATION

Australiahasalonghistoryofdesalination,withitsfirstplantbeingbuiltin1903totreatsalinegroundwaterinthecountry’s

goldfields,anditspopularityrisingbetweenthe1960sand1980s(ElSalibyet al.,2009).Between2006and2013,six

large-scaledesalinationplantswerebuiltinAustraliainresponsetoprolongedperiodsofdroughtandincreasingwater

demands(Bosman,2014).

ThePerthSeawaterDesalinationPlant(PSDP)inthestateofWesternAustraliaisoneexampleofalarge-scaledrinking

waterdesalinationplant(Table6.2),whichwasfinishedin2006,producing144MLperdayoffreshwater(ElSalibyet al.,2009).Itsenergyefficiencyisexemplary,asitconsumesonly3.29kWhperm3thankstoanenergyrecoveryrateofabout

30%(Kemptonet al.,2010).Beforetheimplementationoftheproject,anenvironmentalimpactassessmentwasperformed

todeterminetheeffectsthattheplantwouldhaveonmarineorganisms,emissions,publichealthandsafetyrisks,noise,

surroundingvegetationandAboriginalculturalvalues.Aftertheextensivestudywascompleted,theproposedplantwas

deemedenvironmentallysound,andshortlyafteritsopeningitwasrecognisedastheworldstandardforthattypeofplant,

asitisthelargestdesalinationplantintheworldpoweredbyrenewableenergy(ElSalibyet al.,2009).

Table 6.2 Key operating data for Perth Seawater Desalination Plant (PSDP) (El Saliby et al., 2009).

Indicator Key data

Planttype SWROCapacity 140,000m3/dDesignexpansioncapacity 250,000m3/dSeawatertemperature 16–24°CSalinity 35.000–37.000mg/LEnvironmentalmonitoringrequired TDS,temperature,DO,sedimenthabitatProcessenergyrequirement 4–6–kW/m3

Contracttypes Designandbuild,operateandmaintainContractperiod 25yearsAnticipatedwatercost AUSSI.17/m3

Projectcost AUSS387MRenewableenergy Windfarmviagrid

Figure6.2showsaschematicofthedesalinationprocessatthePSDP,wherebyitpumpspre-treatedseawaterthrougha

seriesoffilters,addsananti-scalantbeforeitispumpedathighpressurethroughROmembranesandthenperforms

post-treatmentbeforeitisdirectedtoanearbyreservoir.

Australiaasawholehasdiversifieditswaterportfolioagreatdeal,activelyusingdemandmanagementtechniquessuch

aseducation,metering,water-savingdevices,low-impactdevelopment(LID)andpricingthat–tovaryingdegrees–reflects

thecostofproduction.Ithasalsoshiftedawayfromgroundwatersources,andincreasinglyusessurfacewater,RWHand

reusetechnology,aswellasdesalination,whileactivelyrechargingaquifers(Mollenkopf,2014).Infact,thecapacityof

desalinationandwaterreuseasaproportionoftotalwaterdemandhasbeensteadilyincreasing(Figure6.3).In2013,the

numberofwaterrecyclingplantsinAustraliawas165,withatotalcapacityof467GL,andthenumberofdesalination

plantswas82,withatotalcapacityof751GL(Radcliffe,2015).


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6.3 HYBRID CONSTRUCTED WETLANDS, CHINA

Constructedwetlands(CWs)havebecomeapopularnaturalmethodoftreatingwastewaterandstormwater,aswellas

creatingriparianbufferzonesandenhancingtheaestheticvalueofanarea.Theyarealsolow-costinbothenergyand

monetaryterms,makingthemfeasibleinbothdevelopedanddevelopingcountries.AninnovativehybridformofCWhas

beensuccessfullyimplementedinsouthernChina,ageneralschematicofwhichisdepictedinFigure6.4.ThisCWwas

designedtohaveasmallsize,makingitidealforsouthernChina,wherelandpricescanbeexorbitantlyhigh.Thehybrid

systemconsistsofavertical-baffledflowwetland(VBFW)andahorizontalsubsurfaceflowwetland(HSFW),aswellas

naturalaerationditches(NADs)toenhancethedissolvedoxygencontentofthedischargedwater,andanoptionalinternal

circulation(IC)system(Zhaiet al.,2011).

Figure 6.3 Total desalination and water reuse capacity in five major urban areas in Australia from 2006 to 2013, compared with the total urban water use in these areas (National Water Commission, 2014).

18001600140012001000800

GL

per

yea

r600400200

Adelaide desalination capacity

Melbourne recycled capacity

Melbourne desalination capacity

Sydney desalination capacity

South East Queensland recycled capacity

South East Queensland desalination capacity

Perth desalination capacity

Desalination and recycled water use*Total urban water use*

0

2006

–07

2007

–08

2008

–09

2009

–10

2010

–11

2011

–12

2012

–13

Figure 6.4 Hybrid constructed wetland schematic, overhead (top) and cross-sectional (bottom) view (reprinted from Water Science & Technology 64 (11), 410–417 (2011) with permission from the copyright holders, IWA Publishing).

Internal circulation (optional)

NADs

Section

Wetland cell

Clear waterpond

HSFWVBFW

Legend: Sampling points of pilot experiment

Septic tank Sediment pond

Reuse ordischarge

Reuse ordischarge

Rawwastewater

Rawwastewater

3 Baffles

3 Baffles

BaffleBaffle

BaffleBaffle


TheuniqueshapesandfeaturesincludedintheVBFW+HSFWwetlandsystemallowittomakeoptimaluseofthe

relativelysmallvolumeofthewetlandbed,andtosimplifyitsoperation.Zhaiet al.(2011)conductedastudyindicatingthat

thesystemissuccessfulattreatingeffluenttomeetwaterqualityguidelineswithminimalcostsandenergyrequirements.

Onthebasisoftestresults,theaverageremovalefficiencyoftheCWsystemforCOD,suspendedsolids,ammonia

nitrogen(NH4+-N),totalnitrogenandtotalphosphoruswerearound84%,95%,72%,65%,and68%,respectively,

exceedingtheperformanceofeitherverticalorhorizontalflowwetlandsalone.

6.4 MADHYA PRADESH, INDIA

Mostgreywaterreuseprojectstendtobeinurbanandperi-urbanareasofdevelopedcountries,andarelessfrequently

exploredinruralareasofdevelopingcountries(Godfreyet al.,2010).However,giventherelativelylowpathogencontent

andhighavailabilityofgreywater,itoffersseveraladvantagesinthesesettings.Godfreyet al.(2010)examinedarural

greywaterreusesystem,whichwasimplementedinschoolsintheprovinceofMadhyaPradesh,India,andby2009was

operatingin300schoolsand1,500householdsowingtoitssuccess.Thesystemisrelativelysimpletoconstructandcan

bemadewithlocallyfoundmaterials.Itconsistsoffivestepstotreathouseholdgreywater,includingabsorption,

sedimentation,filtration,aerationandchlorination.AschematicofthesystemisshowninFigure6.5.First,soapandhairare

absorbedintothespongefilterbeforethewaterflowsintoasettlingtank,wherethesedimentationprocessallowsmost

solidstoberemoved.Fourfiltrationchambersfollowthesettlingtank,whichfilterthewaterwithprogressivelysmallergravel

substrates(from60mmtocoarsesand).Theaerationstageoccursaswaterisaidedbygravitythroughasteptank,and

thenitisstoredinacleanwatertank,wherechlorineisappliedtwiceperweek.

Figure 6.5 Cross-sectional (top) and overhead (bottom) view of greywater treatment system implemented in Madhya Pradesh, India (reprinted from Water Science & Technology 62 (6), 1296–1303 (2010) with permission from the copyright holders, IWA Publishing).

Thetreatedwaterisusedfortoiletflushingandwateringkitchengardens,andusersareeducatedtorefrainfromdirectly

wateringfruitandleafygreenswithgreywater,andtowashand/orcookvegetableswellbeforeeating.Godfreyet al.(2010)

assessedtheefficiencyofthesystembymeasuringfivekeyparameters(TSS,turbidity,BOD,CODandfaecalcoliform)in

boththeinfluentandtheeffluent,toseehowmanycontaminantshadbeenremovedintheprocess(Table6.3).Results

indicatethat–althoughtheeffluentwaterdoesnotmeetpotablestandards–itissafetousefornon-potableuses.The

authorsalsonotethatthesysteminquestioncanbeimplementedatanaffordablecost,thusmakingitoptimalforlow-

incomeareas.Notonlythis,butithelpstoalleviatesanitationissues,asmorewaterismadeavailablefortoiletflushing.


6.5 TENORIO WASTEWATER TREATMENT PLANT, MEXICO

TenorioWastewaterTreatmentPlant(WWTP)inSanLuisPotosi,Mexico,wasthefirsttreatmentfacilityinMexicoto

producemulti-qualityrecycledwaterforavarietyofenduses.Giventhearidclimateoftheregionandover-pumpingofthe

twomainaquifers,freshwaterisminimal,andithasresultedinuntreatedwastewaterbeingusedforagriculturalirrigation.

TheTenorioWWTPusestherecycledwaterforagriculture,industrialuse(powerplant),environmentalenhancementand

groundwaterrestoration.Ithasbeensuccessfullyoperatingsince2006,savingoverUS$18millionfortheconnectedpower

plant(Lazarovaet al.,2014).

TenorioWWTPtreats45%ofthewastewaterfromthecityofSanLuisPotosi,andhasatotalcapacityof90,720m3per

day(Lazarovaet al.,2014).Theprimarytreatmentstepisappliedtoallincomingwastewaterandincludesinitialscreening,

removalofgritandgreaseandprimaryclarification.Afterthisstep,morethanhalfoftheprimarytreatedwaterisdischarged

totheTenorioReservoir–whichwasconvertedtoaconstructedwetland–toremoveorganicmatterandfaecalcoliforms

beforethewaterispumpedforagriculturalirrigation.Thewaterthatisnotallocatedtoirrigationundergoessecondary

treatmentbyactivatedsludgenitrogenremoval,followedbytertiarytreatmentwithsandfiltration,lime,softeningand

chlorinedisinfectiontobeusedforcoolingpurposesinanearbypowerplant(Lazarovaet al.,2014).Aschematicofthe

treatmentprocessisshowninFigure6.6.

Parameter Influent Effluent Efficiency; % or log removal

Suspendedsolids,mg/L 190 120 37Turbidity,NTU 142.5 80 44BOD5,mg/L 187,5 90 52COD(total)tmg/L 529.5 248 53Faecalcoliform,log 4.2–54Ulog/lOOmL 4–4.6Ulog/100mL+ 0.2–0,3

Table 6.3 Efficiency of greywater treatment system, based on five key water quality indicators (reprinted from Water Science & Technology 62 (6), 1296–1303 (2010) with permission from the copyright holders, IWA Publishing).

Figure 6.6 Schematic of Tenorio WWTP in San Luis Potosi, Mexico (reprinted from Journal of Water Reuse and Desalination 4 (1), 18–24 (2014) with permission from the copyright holders, IWA Publishing).

Grit and greaseremoval

Primary clarifierDensadeg

Lifting station 1

Liftingstation 2 Aeration tanks

Secondaryclarifiers

AgriculturalreuseTenorio

reservoir

Sand filtration Softening

Limetreatment

Coolingtower

in powerplant

Liftingstation 3

TheTenorioWWTPsavesabout7.9Mm3ofpotablewaterperannum,improvesthequalityofirrigationwaterand

provideswildlifehabitatthroughwetlandrestoration.Theprimarytreatmentprocessiseffectiveinremovingsuspended

solidsdowntoaconcentrationof82mg/L–whichisfurtherimprovedto28mg/Lafterwetlandtreatment–while

maintainingnutrientcontenttoallowreducedfertiliseruseinagriculture.Inadditiontothis,disinfectionoffaecalcoliformsis

ensuredwitha40dayresidencetimeintheCWsystem.Salinityisalsocontrolledtoreducetheriskofdamagingsalt-

sensitivecrops(Lazarovaet al.,2014).

AnecosystemmonitoringprogrammewassetuptoevaluateenvironmentalhealthinandaroundtheTenorioReservoir

sinceitsmodificationtoperformasawetland.Thestudyfoundthatthepresenceofthewetlandhasenhancedbiodiversity

intheregionbyattractingavarietyofmigratorybirds,aswellasincreasingthenumberofspeciesofsmallmammalsand

flora(Lazarovaet al.,2014).Finally,theprojectledtoseveralsocialandeconomicbenefitsinthearea,includingareduced


incidenceofgastrointestinaldiseasesfromrawwastewater-irrigatedplants,economicbenefitsforfarmersandindustrydue

toamorereliablealternativewatersupply,improvedstandardsoflivingduetoacleanerenvironment,andconservationof

groundwaterresources(Lazarovaet al.,2014).

6.6 GOREANGAB RECLAMATION PLANT, WINDHOEK, NAMIBIA

TheGoreangabReclamationPlant(GRP)inWindhoek,Namibia,hasbeeninoperationsince1969,supplyingdrinking

waterthroughDPR.Theplantsuccessfullyensuressuitablewaterqualitywithmultiplebarriers,includingtreatment,

non-treatmentandoperationalmeasures.Theactualtreatmentprocessincludesacombinationofultrafiltration(UF),

activatedcarbonfiltrationandozonation(seeFigure6.7).

Figure 6.7 Technical schematic of Goreangab Reclamation Plant in Windhoek, Namibia (reprinted from Journal of Water Reuse and Desalination 5 (1), 64–71 (2015) with permission from the copyright holders, IWA Publishing).

pre-ozonationFeed

Q=24.000 m3/d

Cl2

ultrafiltration GAC GAC BAC

(DAF: dissolved air flotation, BAC: biological activated carbon-filter, GAC: granular activated carbon-filter)

ozonation

flocculation rapid sand filtrationflotation (DAF)

Someofthenon-treatmentbarriersincludethefollowing:

• divertingtradewastestoadifferentwatertreatmentplant;

• monitoringatboththeinletandoutletpointsofthefacility;

• constantmonitoringofpotablewaterquality;

• blendingofreclaimedwaterwithotherpotablewatersources;

• activecommunityengagementprogrammetoimprovepublicacceptance.

AlongwiththeGRP’streatmentprocesses–whichensurethatbetweenoneandfourbarriersareinplaceforeach

identifiedwaterqualityparameter–theaboveactionshelptoensurethatsafedrinkingwaterisobtainedfromtheplant

(Lawet al.,2015).

6.7 GUELPH, CANADA

TheCityofGuelphinOntario,Canada,isaprominentexampleofamunicipalityusingdemandmanagementstrategies

effectively.Asacitythatgets100%ofitsdrinkingwaterfromaquifers,theimportanceofconservingthatfiniteresourceis

crucial.In1998,theCitybeganaWaterConservationandEfficiencyStudy,followedbyimplementationofaWaterSupply

MasterPlanin2004(CityofGuelph,2009).

IncludedintheCity’sdemandmanagementmechanismsare(GreatLakesCommission,2015)thefollowing:

• rebatesonwater-efficienttoiletsandwashingmachines;

• Blue Built Homecertificationprogramme–basedonthepresenceofefficienthomefixtures;

• incentivesforinstallinghomegreywaterreuseorRWHsystems;


• institutional,residentialandindustrial(ICI)auditandcapacitybuyback–paysusersforretrofitsthatpermanently

reducewaterconsumption;

• freeauditstoassesshomewaterandenergyefficiency,plusfreeretrofits;

• freeconsultationstoimprovegardenandlandscapewateruse.

ToiletandwashingmachinerebatesandtheICIcapacitybuybackaloneresultedinover400,000m3ofwatersavingsina

5-yearperiod(CityofGuelph,2009).

Overall,Guelph’swaterconservationprogrammeshaveresultedinsavingsofaround10,000m3perday,despitea

15,000personpopulationincrease(GreatLakesCommission,2015),makingthepercapitawateruseoftheaverage

Guelphresidentnearlyone-thirdlowerthanthatoftheaverageCanadian(CityofGuelph,2013).NotonlyistheCity

conservingfreshwater,buttheirdemandmanagementprogrammeshaveresultedinfinancialbenefitsofclosetosixtimes

theinitialinvestmentinavoidedsupply,capacityandwastewatercosts(Table6.4).

Table 6.4 Present value of total costs and benefits of each City of Guelph demand management strategy (Great Lakes Commission, 2015).

Activity Name PV Cost ($) PV Benefit ($) NPV ($)

RoyalFlushToiletRebate,SF $1,676,300 $12,068,155 $10,391,855RoyalFlushToiletRebate,MF $525.400 $2,534,944 $2,009,544RoyalFlushToiletRebate,IQ $55,600 $441,405 $195,605SmartWashWashingMachineRebate $1,333,250 $4,506,374 $3,473.124BlueBuiltHome-Bronze $329.2S0 $545,125 $215,546BlueBuiltHome-Silver $15,900 $21,467 $5,587GreywaterReuseSystems $21,000 $3,157 $(17,843)ICIAuditandCapacityBuybackProgram $967,395 $12,323,719 $11,356,324RainwaterHarvestingSystem $50,000 $7,264 $(42,736)HealthyLandscapeVisit $368.970 $36,022 $(332,948)EfficientHomeVisitSurveys(GEL/NetZeroCity) $229,505 $24,127 $(205,378)Total $5,572,800 $32,811,780 $27,238,980

Byimplementingawidevarietyofdemandmanagementstrategies,aswellasencouragingsmall-scaleacquisitionof

AWRthroughgreywaterreuseandRWH,theCityofGuelphdisplaysexemplaryunderstandingofintegratedwatersupply

management.

6.8 BORA BORA, FRENCH POLYNESIA

TheFrenchPolynesianislandofBoraBorawasexperiencingincreasingwatershortagesduetodwindlingrainfall,increased

developmentandalargetourismsector.Sincetheexistingfreshwaterresourcesontheislandwerenotsufficienttomeet

theneedsofpermanentresidentsplusthelargeinfluxoftourists,itwasimperativethatwaterreuseanddesalinationbe

implemented.Additionally,thelagoonecosystemstypicalofFrenchPolynesiaarefragile,andthedischargeofuntreated

waterposesaseriousrisktolocalfloraandfauna,creatinganotherincentivetoreusewater.BoraBorafinallyputawater

recyclingprogrammeintoplace,butseveralconstraintshadtobeaddressedtoensurecommunityacceptanceofthe

programme(Lazarovaet al.,2012).

Twowastewatertreatmentplantshavebeenimplementedontheisland,usingUFtotreatreclaimedwatertoEuropean

standardsforbathingwater(Table6.5).Therecycledwaterisstoredinacoveredreservoiraftertreatment,thenchlorinated

andpumpedthroughanon-potabledistributionnetwork.In2010,solarphotovoltaicenergywasappliedtoimprovethe

overallenergyefficiencyoftheprogramme.DesalinationisalsobeingutilisedinBoraBora,withthreeROplantshaving

beenimplementedsince2000(Lazarovaet al.,2012).

AccordingtoLazarovaet al.(2012),themainapproachtoincreasingpublicacceptanceofwaterreuseinBoraBorawas

communityconsultation,whichincludedthefollowing:

• publicforumsandinterestgroups;

• consultinginterestgroupsandholdingworkshops;


• educationprogrammesindicatingthesafetyofthereusescheme,aswellastheneedforsuchaprojectgiventhe

waterconstraints;

• collaborationwithmediatomarketreclaimedwaterasasustainablesolution.

Asaresultofthesepublicengagementinitiatives,demandforreclaimedwaterinBoraBorahasincreased,ashasthe

numberofend-users,whichdoubledaftertertiaryUFtreatmentwasimplemented.Recycledwaterisnowusedforboat-

washing,landscapeirrigation,fireprotection,industrialuses,large-scalecleaningandothernon-potableuses(Lazarova

et al.,2012).

Inadditiontocommunityconsultationprocesses,pricingmechanismswereputintoplace,consistingoffixedand

volumetriccostschosentoreflectthewillingness-to-payofconsumers.BoraBoraputinplaceatwo-partpricingstructure

withadecliningblockratewithlowerperunitpricesthanpotablewater.Largeend-usersandtourism-relatedbusinesses

helpedtoincreasepublicacceptanceofreusedwaterbyprovidingfundingtothereuseindustry,whichhelpedtokeep

costslowforsmallconsumers(Lazarovaet al.,2012).

AsaresultofBoraBora’sexpandedwaterportfolio,freshwaterresourcesarebeingconserved,thelagoonenvironmentis

beingprotected,businessesarereapingeconomicbenefits,andthecommunityasawholeisadoptingandacceptingmore

sustainablepractices.Inadditiontothefacilitiesalreadyinplace,BoraBorawouldliketoextendtheoperationtoincludea

morewidespreadnetworkoffireprotectioninfrastructureandaUF/ROmembranefacilityfortheproductionofpotable

water(Lazarovaet al.,2012).

6.9 KOGARAH, SYDNEY, AUSTRALIA

AsuccessfulexampleofadualRWHandstormwatercollectionsystemisbeingusedinthetownsquareofKogarah,a

suburbofSydney,Australia,adepictionofwhichisshowninFigure6.8.Stormwaterrunofffirstflowsthroughagross

pollutanttrap(GPT)toremovelargerparticlesandlitter,beforebeingcollectedinastoragetankfor“dirty”water.Itis

storedthereuntilitisreadytobeusedforirrigationofgreenspacesinsurroundingcourtyards,whichactasbio-filtersand

removesomeofthefinerpollutants.Itiscollectedonceagainafterithaspercolatedthroughthebio-filterandstoredina

“clean”watertank,locatedadjacenttothedirtywatertank(Chananet al.,2010).

Alsocollectedinthecleanwatertankisrainwaterfromrooftops.Thiswaterisusedfortoiletflushingandcarwashing,as

wellastotopupothertankswhenwaterlevelsarelow.Eighty-fivepercentofprecipitationthatfallsonthesquareisused

intheareathroughthedescribedsystem.Itisestimatedthatbetweenthereuseofrainwaterandstormwater,approximately

7,920kLofpotablewateraresavedannually(Chananet al.,2010).

Totreatstormwaterfromthelargercatchmentarea,a9,500m2constructedwetlandwasalsoimplementedinKogarah,

which–incombinationwithaGPT–treats95%ofstormwaterrunoffinthecatchment.Stormwaterentersthewetlandat

oneendwherethe2mdepthallowssedimentsandheavymetalstosettleandremainundisturbed;thenflowsthrougha

shallowsectioninthemiddlewheremacrophytesarepresenttoaidinnutrientfiltration;andfinally,thebreakdownof

bacteriaisaidedinafinal,deepersectionbysunlightandwind.Aftertheentireprocessiscompleted,anoutletpipecarries

thetreatedstormwatertoOatleyBay,apopularrecreationarea.Theconstructionofthiswetlandhasdrasticallyimproved

Parameter Raw sewage

Secondary effluent Recycled water (UF permeate)

Measured Consent Measured Guide value

COD(mg/L) 595(270–837) 31(21–65) 90 15(4–34) 40BOD5(mg/L) 349(200–540) 7(<5–22) 25 4(1–6) 20TSS(mg/L) 238(125–275) 9.5(4–19) 35 <5 20Ntot(mg/L) 47(30–70) 8.3(2–18) 20 7.3(2–17) 20Ptot(mg/L) 6.8(4.1–8.1) 2.5(1.0–5.8) – 1.9(0.45–5.8) –E. coli/100mL ND 105–107 – Non-detected 0/100mL

aAveragevalueandlimitofvariations(monthlycompositesamples,excludingE. coli.thatwasmonitoredingrabsamples).

Table 6.5 Measurement of water quality indicators at several stages in the treatment process, from raw sewage to treated recycled water (reprinted from Journal of Water Reuse and Desalination 2 (1), 1–12 (2012) with permission from the copyright holders, IWA Publishing).


thequalityofstormwaterabovepre-constructionlevels,whichwerepreviouslyveryhighinheavymetalsandotherpollutants

(Chananet al.,2010).

6.10 STAR CITY, SEOUL, SOUTH KOREA

Inoperationsince2007,StarCityisalargereal-estatedevelopmentinasuburbofSeoul,SouthKorea,thatishometo

morethan1,300apartmentsinfourhigh-risebuildings.ThedevelopmentfeaturesaninnovativeRWHsystemthatisused

simultaneouslyforfloodprevention,waterconservationandemergencyresponsepurposes.Thesubjectofworldwide

acclaim,itssuccesshasresultedinothercitiesacrossSouthKoreaimplementingsystemsofsimilardesign.HanandMun

(2011)collected2yearsofoperationaldatafromStarCitytoassesswaterandenergysavings,waterqualityandrunoff

control.

AschematicoftheStarCityRWHsystemisdepictedinFigure6.9.Thetotalroofcatchmentareais6,200m2ofrooftop

and45,000m2ofterrace,andthestoragecapacityis3,000m3ofwaterstoredinthree1,000m3tanks.Twoofthethree

tanksstorerainwatercollectedfromrooftopsaswellastheground;thiswaterisusedforgardenirrigation,andisthen

recycledandstoredforfurtheruse.Thethirdtankholdstreated,emergencytapwater.Theissueofthistank’swaterquality

deterioratingovertimeisaddressedbypumpinghalfofitsvolumeintooneoftherainwatertanksatregularintervalsand

replenishingitwithafreshsupply.Screensandfiltersarepresentattankinletstomaintainquality,andcalminletsand

floatingsuctiondevicesareusedtoavoidre-suspendingsediments(HanandMun,2011).

Uponanalysisofthesystem,HanandMun(2011)foundthatitconservesavolumeofapproximately26,000m3peryear

ofpotablewater,whichiscloseto50%ofthetotalprecipitationthatfallsovertheareaoftheStarCitycomplex.By

recyclingirrigationwateraswellasstoringunusedwaterfromonemonthtothenext,thesystemisabletomaintainfairly

consistentusagethroughouttheyear.AllwatertestedinthestudyhadturbiditylevelsbelowtheKoreanGrayWater

Standard(KGWS)(<1.5NTU)andpHwithintherangespecified(6–8.4)intheKoreanDrinkingWaterStandard(KDWS).

HanandMunalsoassessedtherunoffcontrolpotentialofthesystem,whichisillustratedinFigure6.10.Thetankvolume

tocatchmentarearatioofthesystemis5.8m3/100m2,meaningthatintheeventofa50-yearstormwithapeakflowof

Figure 6.8 Flows through Kogarah RW/SW harvesting system. Included components are “clean” water for toilet flushing (light blue), rooftop-harvested rainwater (medium blue) and stormwater (dark blue) (reprinted from Water Science & Technology 62 (12), 2854–2861 (2010) with permission from the copyright holders, IWA Publishing).


27m3/hour,theStarCitytankcouldreducethepeakflowdischargeto20m3/hour,equivalenttoa10-yearstormevent.

StarCityisalsoestimatedtosaveapproximately8.9MWhofelectricityeveryyear,owingtothereducedneedforthe

treatmentandconveyanceofpotablewater.

6.11 DECENTRALISED WATER REUSE WITH ZERO DISCHARGE, CHINA

AwaterreclamationandreusesystemwasdesignedandinstalledinXi’anSiyuanUniversitylocatedinthesoutheast

suburbanareaofXi’anCity,China.AsshowninFigure6.12,watersupplyinthisuniversitydependedongroundwaterwells

withacapacityof2,800m3perday;whichcouldmeetthedemandforpotableusesforupto35,000studentslivinginthe

campus,butwasinsufficientforcoveringallthenon-potableconsumptionasprojectedinTable6.6(Wanget al.,2015).

Afterpotableuse,thecollectedusedwaterissenttotheon-campustreatmentstationwhereasophisticatedprocess

(Figure6.11)isusedforwaterreclamationbycombiningananaerobic–anoxic–oxic(A2O)unitwithamembranebioreactor

(MBR)fortheproductionofhigh-qualityreclaimedwater.Toenlargethesourceforwaterreclamation,thereclaimedwater

–afterbeingusedfortoiletflushing–isalsocollectedandaddedtothetreatmentstationinflow.Asaresult,thepotential

ofreclaimedwaterproductionbecomeslargerthantheoriginalgroundwatersourceandeverydropofusedwaterisadded

Figure 6.9 Star City, South Korea, RWH system schematic (reprinted from Water Science & Technology 63 (12), 2796–2801 (2011) with permission from the copyright holders, IWA Publishing).

Ground surface Man-hole

Man-hole

Man-hole

Man-hole

RoofcatchmentFrom emergency tank

Tapwater

Store for Emergency Collect fromground surface

Collect fromroof catchment

Fourth below-ground floor in Building B

M.H

Filter

Figure 6.10 Runoff control potential for flood events from 5 to 100 years in magnitude, according to RWH tank volume (reprinted from Water Science & Technology 63 (12), 2796–2801 (2011) with permission from the copyright holders, IWA Publishing).

35

30

Qpe

ak (

m3 /h

r)

25

20

15

10

5

0

0 1 2 3 4 5 6 7 8 9 10

Tank volume (m3/100m3)

11 12 13 14 15 16 17 18 19 2055.8

5 yearDesign periods

10 year30 year50 year100 year


tothesourceforwaterreclamation,insteadofbeingcategorisedas‘waste’tobedischarged(Huet al.,2013;Wanget al.,2015).

AnoticeablefeatureofthesystemshowninFigure6.12istheintroductionofaso-called‘environmentallake’,which

performsthefunctionsofbothwaterlandscapingandstorage.Multi-stepwaterusehasalsobeenrealisedbysupplying

reclaimedwater,firstlytoaseriesofwaterlandscapesbeforethelake,andthenpumpingwaterfromthelakeforoutdoor

gardeningandindoortoiletflushing.Therefore,thehydraulicretentiontimeofwaterinthelakeisdynamicallycontrolledat

about5–7dayswithoutadditionalwaterconsumptionforitsreplenishment.Agreencampushasthusbeencompletely

nourishedbysufficientreclaimedwaterthroughazerodischargeandefficientwaterreusesystem(Wanget al.,2015).

6.12 SCHOOL DRINKING WATER SUPPLY IN HANOI, VIETNAM

CukheElementarySchoolislocatedinCukheVillage,inthesouthernpartofHanoi,Vietnam.Theschoolhas300students,

15teachersand3buildingswithrelativelysecureandsuitableroofs.Inthepast,theyhavehadtouseexpensivebottled

Figure 6.12 Configuration of the campus water reuse system (Wang et al., 2015).

Figure 6.11 The used-water treatment and reclamation process (Hu et al., 2013).

Table 6.6 Projection of non-potable water demands (Wang et al., 2015).

Water use Specification Quantity Demand Remarks

1 Toiletflushing 30L/d/person 25,000–35,000persons 750–1050m3/d2 Gardening 3L/m2/d 50,0000m2 1500m3/d For50hectaresgreenbelt3 Lakereplenishment 20%daily

replacement50,000m3 1000m3 Forlakesof5,000m2and

1mdepth4 Lakewaterloss 20%oflake

replenishment1,000m3 200m3 Evaporationandotherloss

5 Total 3,450–3,750m3/d Includingitem32,450–2,750m3/d Excludingitem3


waterfordrinkingbecauseofarseniccontaminationinthelocalgroundwater.InJuly2014,anewapproachwasintroduced

andtheLotteDepartmentStoredonatedmoneyforarainwatersystemaspartofitscorporatesocialresponsibility(CSR)

commitment.AteamfromSeoulNationalUniversity(SNU)designedthesystem,whichconsistsofa180m2roof

catchment,gutter,firstflushtank,two6m3rainwaterholdingtanks,andUVfiltersnearthetap(Figure6.13).Localpeople

usinglocallysourcedmaterialsconstructedthesystem,andfollowingconstruction,boththeresidentsandthedonor

companyweresatisfiedwiththeoutcome.Waterlevelgaugesandwatermeterswereinstalledtomonitorremainingwater

suppliesandcumulativewaterconsumption.About6m3rainwatercanbesavedfromtheRWHfacilitiespermonth,which

meansUS$150canbesavedmonthlyasaresultofnothavingtobuybottledwater.Thisisequivalentofbuildinganother

community-basedRWHsystemevery2years(US$3,600).

Figure 6.13 Rainwater tank at Cukhe Primary School, Vietnam (provided by Mooyoung Han).

Catchment

Kindergarten 150 m2 6,000L × 2 = 12,000L

School Area Volume of Tank

PrimarySchool

80 m2 5,000L × 2 = 10,000L

Filter

First Flush

First Flush

Tap

Drain

Water Meter

Vent

Drain Drain

Drain

Calm-inlet

Vent

InflowScreen

Overflow

Figure 6.14 The rain gauge installed at Cukhe Primary School, Vietnam.

Anotherprominentissueintheareawasinsufficientrainfalldata,asmostrainfalldataarecollectedinurbancentres.

Therefore,CukheVillagedidnothaveadequaterainfalldatatomakeapreciseRWHdesign.Thesolutionwastoinstalla

simplerainfallgaugeandworkwithagroupofsciencestudentstomaintainrainfallrecordsviaawebsite(Figure6.14),

whichtheycanthenuseinfuturedesigns.

Thelessonslearnedfromthiscasestudyarethreefold:theimportanceofbuildinglocalresidents’capacitytodesign,

build,andoperateRWHsystems;theimportanceofinvolvingindustrythroughCSRactivitiesasawin–winstrategy;and

thebenefitoflocaldatacollectionbystudents,whichresultedindemocraticdesigndecisionsthatcanbeusedas

referenceforfuturedesignsandoperations.

48AlternAtiveWAterresourcescluster

7 KNOWLEDGE AND TECHNOLOGY GAPSThe following section and section8 incorporate ideas and recommendations from experts in AWR-related fields. All the knowledge contained in these sections is that of the contacted professionals, unless a different source is cited. Individual contributors are listed in the document under “Key Contributors”.

DespitemanypromisingtechnologiesemerginginAWrsectors,therestillexistsomeprominentgapsinthepresent

knowledge,practicesandtechnology.someexamplesofthesegapswillbeidentifiedandexplainedinthissection.

7.1 DATA COLLECTION AND INTEGRATION

today,mathematicalmodellinghasbecomefundamentalfornaturalresourcesmanagement,inparticularforwaterresources.

Governmentalagenciesrelyonmodelstomanagecurrentconditionsandforecastfuturestrategies.However,gapsstill

exist–particularlyinlessdevelopedcountries–inwhichinformationareroughlycollectedandrarelymadepublicina

completeform.

thelackofconsistentdatainthewatersectorcanleadtopoorunderstandingofthepresentconditionsand

effectivenesswatermanagementplans,alackoftrustfromthepublicanddifficultycomplyingwithregulations.Freeand

opendata,availabletoresearchinstitutesandcitizens,helptoclarifycurrentwaterresourcesconditionsandincreasesocial

awareness.effortsmustbemadeattheinternationalleveltodevelopacommonnetworkfordatapresentationand

interpretation.notonlythis,butsocial,economic,healthandengineeringdatashouldbeintegratedunderacommon

frameworktomakescience-basedandrisk-baseddecisions.thistypeofframeworkcurrentlydoesnotexist,butis

necessaryforcreatingsaferandmorerobustwatersupplysystems.

7.2 FRAMEWORK FOR ASSESSING CASE-BY-CASE SCENARIOS ON THE BASIS OF ENVIRONMENTAL IMPACT AND COST-EFFECTIVENESS

eachwaterdeficientsituationneedsanoptimisedsolution,butacommonsolutionforeverycasedoesnotexist.the

fundamentalpointistofindanoptimalsolutiontailoredtoeachindividualscenariothatcompromisesbetweensocial,

economicandenvironmentalobjectives,whilekeepinginmindsustainabledevelopmentgoals.

thereisapresentlackofacomprehensiveframeworkorguidancetoolforselectingspecifictechnologiesand

managementstrategiesthatcanbeadaptedonacase-by-casebasis.thecreationofsuchadocumentisessentialto

makingdecisionsthatwillbesustainableinthelong-run.thisisespeciallyimportantintheAWrsector,wherenew

technologiesareconstantlyemergingandmaynotyethaveundergonewidespreadimplementationorhadtheopportunityto

buildareputation.thereisstillconsiderableroomforimprovingknowledgeofcostandenvironmentalsolutionsthatare

effectiveandreliableovertime.

7.3 MORE EFFECTIVE AND RELIABLE WATER SOLUTIONS FOR ARID CLIMATES

thecreationofsafeandreliablewatersuppliesinaridregionsisstillagreatchallengearoundtheworld.Areaswithout

sufficientgroundandsurfacewatertomeettheirneedsmayexperienceareducedqualityoflifeiftheylackthecapacityto

obtainwaterfromelsewhereortoharnessAWr.Moreattentionisneededincreatingsolutionsthatincreasewater

availabilitywherefewoptionsareavailable,anddosoinawaythatcanbeadjustedtofittheeconomicandenvironmental

capabilitiesoftheregioninquestion.thismayinvolvecreatingmoreeffectivewaterstoragesolutions,implementing

high-efficiencywaterreuseschemes,utilisingwater-savingtechnologyorsubstitutingprocessesthatusewaterforonesthat

donot.

thisneedalsoappliestoregionsinwhichdryseasonwaterneedscannotbemetbywatermadeavailableinthewet

season.Forexample,problemsstillexistwithmanagingcollectedrainwatereffectivelyfromthewettodryseasons.often

thereisstillnotadequatestoragecapacitytoprotectagainstsignificantdryseasonshortages.tomitigatetheseissues,a

shiftinconsumptionpatternsmustoccursothatlowerratesofutilisationoccurinthedryseason(Mwamilaet al.,2015).


theimplementationofadualwatersupplythatusesrainwaterfordrinkingandreclaimedwaterfornon-potableuses

wouldhelptoslowtherateofdepletionofexistingfreshwatersources.engineeringsimulationsshouldbeconductedforthe

optimaldesignofthiskindofsystem(nguyenandHan,2014).

7.4 HIGH RATES OF WATER LOSS

Amajorproblemaffectingwaterutilitiesaroundtheworldisthehugeamountofwaterbeinglostfromwatersupplyand

distributionnetworks.Ahighlevelofwaterlossisaproxyindicatorofapoorlyrunwaterutilityreflectinghugevolumesof

waterbeinglostthroughleaksornotbeinginvoicedtotheconsumers,orboth.theWorldBankconservativelyestimated

thatthewaterlostdailyacrosstheworldthroughleakageinthedistributionnetworkswouldbesufficienttoservenearly

200millionpeople.inaddition,30millionm3aredeliveredeverydaytocustomers,butarenotinvoicedbecauseof

pilferage,corruption,andpoormetering(Kingdomet al.,2006).

Waterlossreductionwouldhaveanimmediateoperationalandfinancialbenefittothewaterutilities,andthisshould

capturetheattentionofallconcernedparticularlylocalauthoritiesandgovernments.reducingwaterlossesrepresentsa

cheapAWr,whichcanbeprovidedatamuchlowercostthanotherviableoptions.thecontinuouslyrisingcostof

producing,treating,transporting,storinganddistributingwaterpresentsnewopportunitiesforthecreationofinnovative

strategiesandtechnologies.solutionsmustbeprovidedtotheproblemsofexcessiveleakage,inaccuratebilling,network

inefficiency,excessiveenergyuse,etc.

7.5 LACK OF PUBLIC ACCEPTANCE OF RECLAIMED WATER

oneofthemajorchallengesrelatedtotheuseofreclaimedwaterishowtoovercomethepsychologicalbarrierassociated

withthistypeofuse.Manytechnologiesexistwhichcanproducesafeandreliablereclaimedwater,butitstillcarriesan

inherent“yuckfactor”whichmustbeovercomebeforewidespreadimplementationcanbefeasible.thisbarrierdoesnotjust

existinregardstopotableuse.theuseofreclaimedwaterforbathing,laundry,carwashingandevengardeningcan

becomeproblematicwhenusersdonottrustitssafetyorquality.

overcomingthisobstaclerequirestheuseofawarenessprogrammestargetedateducatingthepubliconthesafetyand

treatmentprocessesofreclaimedwater.evenwiththesekindofprogrammes,publicacceptancecanbeslow,andtherefore

long-termstrategiesmayneedtobeused.safeandsuccessfulwaterreusetechnologiesshouldbemadevisibleto

enhancethetrustandacceptanceofcommunities.

7.6 SAFETY AND SUSTAINABILITY IN TRANSPORTATION

transportationofwateriscriticaltothefunctioningofallwatersupplysystems.However,multipleissuescanarisein

transportation,particularlywithregardstoitssafetyandsustainability.

ifalternativewatersourcesareassociatedwithdifferenttypesofuse(i.e.potableandnon-potable)sharingthesame

space,theriskofcrossconnectionsisanissue,particularlybecausethesearetypicallyburiedpipes.thisriskofcross

contaminationmayhavesevereconsequences(e.g.publichealth).colourcodesforthepipesorsimilarsolutionsdonot

provideahighenoughlevelofsafetyandotherexistingsolutionsbringaddedcoststoconstructionandmaintenanceofthe

networks.thereneedtobeasmanynetworksastherearedifferentwaterqualitytypes,andtheseneedtocoexistwith

minimalcrossconnectionrisk.Morecreative,effectiveandcost-efficientsolutionsareneeded.

Manyexpertsinthewatersectorhavealsorecognisedthattransportingwaterlongdistancesmaynotbesustainablein

thefuture.Firstly,theactofpumpingwatertoanotherregionusuallyrequiresagreatdealofenergy,andthereforecanbe

cost-intensiveandemissions-intensive.Further,relyingonwaterbeingpumpedfromadistancemaycauseproblems,

particularlyinthecaseofanemergency,naturaldisasterorsignificantwatershortage.Plansshouldbemadewhichtake

intoaccountthepossibilityofunforeseencircumstancesandincorporateappropriatecontingencyplanningclauses.


8 RECOMMENDATIONS

8.1 AWR VISIBILITY

ItisimportanttomakeAWRmorevisiblewithinthefieldsofscience,engineering,politicsandbusinessaswellaswiththe

generalpublic.Spreadingknowledgeandunderstandingofnewtechnologieswillhopefullyincreasepublicacceptanceand

promotetheirusewithinwatersupplysystems.

AgoodwaytopromoteAWRistopresentvaluablecasestudiesinwhichthedesiredgoal(s)hasbeenreachedanda

moresustainablewatersupplyhasbeencreated.Scientists,techniciansandcitizenscanusetheirrespectivework,

knowledgeandexperiencetoimprovethevisibilityofsustainableprojects.Networksshouldbecreatedbetweendifferent

sectorsofsocietyandacommonspaceshouldbefoundinwhichtocreateatransparentandopenframeworkforthe

developmentofAWRprojects.

Tobuildcapacityandmomentum,implementationmaystartsmall,suchaswithhousehold-scaleRWHorgreywaterreuse

systems,focusingontheeducationandskilldevelopmentofusers.Thisisabottom-upmethodofincreasingawarenessand

understandingofAWRoptions,andmakingthegeneralpublicmoreinvestedincreatingsustainablewatersupplies.

InadditiontoincreasingthevisibilityofAWR,therationalebehinditsimplementationshouldbewell-known.AWRasan

optionforcreatingmoresustainablewatersupplieswouldbenefitfrombeingmoreprominentineducation,andthevalueof

waterinenvironmental,economic,culturalandsocialcontextsmaybetaughttochildrenfromayoungagetoensurethat

theseprinciplesareunderstoodwellinfuturegenerations.

8.2 TECHNOLOGICAL ADVANCEMENT

Thedevelopmentofadvancedtechnologiesforwatermanagementshouldbeongoingandhighlyvalued.Thewatersector

hasseenmuchimportanttechnologicaladvancement,whichhasallowedtheprovisionofhigherqualitywateratalower

costandwithlessimpactontheenvironment.However,thesetechnologiescanalwaysbeimprovedtomakethemmore

efficient,reliable,cost-effectiveandenvironmentallyfriendly.

Forexample,theuseofrenewableenergyinwatertreatmentisbecomingincreasinglypopular,andimprovingthe

reliabilityandefficiencyofthesetechnologiescouldhavelargebenefitsforthewatersectorandtheenvironment.

Additionally,RWHhasbeenaroundforcenturies,buttechnologicalimprovementscontinuetomakeitmoreableto

effectivelyaugmentthewatersupply.Makingthesesystemsmoreautomated,low-maintenanceanduser-friendlymayhelpto

promotewidespreadimplementationofsmall-scalesystems,whichtogethercansavevastamountsofpotablewater.

Waterlossmanagementisalsoafieldinwhichtechnologicaladvancementcurrentlyhasandwillcontinuetohaveagreat

impactontheefficiencyofwatersupplysystems.Someoftheareasinwhichtechnologyhasbeenadvancingandfurther

workiscurrentlybeingundertakenarewaterqualitysensors,communicationequipment,datamanagementsoftware,

real-timesupervisorycontrolanddataacquisitionsystems,remotecontrolofequipmentsuchaspumpsandvalves,automatic

meterreading,etc.Broadareasinwhichcontinueddevelopmentoftechnologieswouldenhancefurtherimprovementof

waterdistributionnetworksincludesmartmetering,waterquality,energyefficiency,leakagemanagementanddataanalysis.

Althoughmuchofthisknowledgeisalreadyavailable,applyingiteffectivelyandwithproperforesightisimportant.

8.3 FRAMEWORK FOR AWR ASSESSMENT

TherecurrentlyexistnoclearlydefinedmetricsforquantitativelymeasuringandcomparingdifferentAWRoptions.For

example,itmaybepossibletomeasurethecostsandbenefitsoftwodifferentdesalinationschemes,buthowwouldone

definitivelychoosebetweenawaterreuseschemeandonethatusesdemandmanagement,takingintoaccountthe

life-cyclecosts,benefitsandoverallsustainabilityandresiliencyofeachsystem?

AcomprehensiveframeworkforbenchmarkingAWRtechnologiesandstrategiesisneeded.Thisframeworkwillinclude

toolsforquantitativelyandqualitativelyassessingwatermanagementstrategies.Thiswillaidinthedecision-makingprocess

andcontributetothedevelopmentofamorereliableandsustainablewatersupply.TheAWRClustercouldplayacrucial

roleinthedevelopmentofsuchaframework.


8.4 SYSTEM RECONFIGURATION

Aparadigmshiftshouldoccur,withrespecttothewayurbanwatersystemsaredesigned.Newsystemswouldbenefitfrom

havingenclosedwatercycleswithminimalfreshwatersuppliedandminimalwastedischarged(seeexampleinFigure8.1).

Toaccomplishthis,subsystemsofurbanwatercycles(e.g.,supply,sewerage,reuseandenvironment)shouldbe

harmonicallyintegratedintoacombinedframework.Inthisframework,wastewatershouldbeviewedasaresource,and

naturalorartificialwaterbodiesshouldbeanimportantpartofthesesystems,tobereplenishedandusedforwaterquantity

regulationandwaterqualitypolishing(Wanget al.,2015).

Figure 8.1 A cyclical urban water supply, in which resources are recovered to the furthest extent possible, discharge of waste is minimised and natural and artificial water bodies are used as buffers (Tambo et al., 2012).

Insustainablewatersystems,WWTPsshouldbeconceivedlessaspollutioncontrolsystemsandmoreasresidue

valorisationsystems.Manyeffortsarecurrentlymadetorecoverresourcesbothinthewaterandinthesludgelines.Biogas

productionandvaluablechemicalsrecoveryarejustsomeofmainfoci.Theseeffortsshareacommonbackground:the

directionthroughenergy-efficient,sociallyacceptableandenvironmentallysoundwastewatermanagementsystems.The

reliabilityofthesesystems,aswellasotherkindsofwatertreatmentsystems,willincreaseastechnologyimprovesand

regulatoryframeworksadjusttotheuseofreclaimedwater.

Thesecyclicalsystemswouldbenefitfromfocusingonintegratingfeaturestoservemultiplepurposes.Forexample,a

greenroofwitharainwatercollectionfunctioncreatesacommunityspace,producesfood,providesacoolingamenityfor

thebuilding,mitigatesfloodriskandmakesfreshwateravailableforotheruses;naturalorman-madelakescreate

environmentalbufferstoaidinwatertreatment,createaestheticvalueandmayenhancebiodiversity;waterreuseaugments

thetotalwatersupply,decreasescontaminantsintheenvironmentandcreatesopportunitiesforenergygenerationandthe

recoveryofotherresources.Systemsshouldbeevaluatedintheframeworkofthewater–energynexustoensure

sustainabilityinbothaspects.

Potentialbarrierstoimplementationofcyclicalsystemsincludewaterqualityregulations,largeinvestmentsoftime,

moneyandmaterialsthatmaybenecessaryinreconfiguringanentiresystem,andsocietaloppositiontousingreclaimed

water.

8.5 IT-FOR-PURPOSE TREATMENT AND UTILISATION

Manyend-usesforwaterdonotnecessitatetheuseofpotablewater.Inmanycities,thequantityofwaterthatneedstobe

ofdrinkablequalitycomprisesnomorethanhalfoftheentirepotablewaterquantitysupplied,eveninhouseholds.Inwater

usedformunicipal,commercial,industrialandagriculturalpurposes,thispercentageismuchhigher.

Asmarterwaytoutilisewateristocategorisetherequirementsforwaterqualityintovariousgradesandthentocompare

therequirementswiththeintrinsicqualitiesofthewaterfromeachalternativesource.Thismethodisfit-for-purposesource


selectionandfit-for-purposewatertreatment.Inthisway,wateruseefficiencycanbemaximised,andenergyconsumption

minimised.

Forexample,directuseofrainwaterafteronlysimplesedimentationprocessesispossible,asiscurrentlybeingpractised

inmanyAustralianhousesandcommunities.Tertiarywastewatertreatmentmaynotberequiredwhenthetreatedeffluentis

usedforagriculturalirrigation,becauseresidualsuspendedsolids,organics,nutrientsmaynothavenegativeimpactson

cropgrowth;theseconstituentsmayevenimprovecropyield.Seawatercanbedirectlyusedfortoiletflushing,withoutthe

needfordesalination,asispracticedinHongKong(section6.1).Finally,multi-stepreclaimedwaterusecanbemade

possibletoincreasetheefficiencyofwaterutilisationandiscurrentlybeingimplementedinMexico(section6.5).

Onepossiblechallengewhenimplementingfit-for-purposetreatmentisthepresenceofwaterqualityregulations,

whichmayrestricttheuseofwaterbelowacertainquality.Sincestandardsandregulationscanvarygreatlybylocation,

technologicalsolutionsforwaterreuseandtheirimplementationplansmustbetailoredtolocalguidelines.Implementers

maybenefitfromtakinglessonsfromsimilarjurisdictions,andfromcreatingsystemsthatcanbeamendedeasilywithsmall

changestotechnologyandregulatoryframeworks.Tocreatefewerproblemsinthefuture,regulationsmaybemadeflexible

enoughtorespondtorapidlyevolvingtechnologywhenpossible.Inanotherrespect,regulationsthatareinplacetoimprove

resourceefficiencymayactuallypromotetheuseoffit-for-purposetreatment,ratherthandeterit(UNWater,2015a).

8.6 DYNAMIC STRATEGIES

Animportantfactorwhencreatingwatermanagementstrategiesisthedynamicnatureofthewatersector.Newchallenges,

concernsandcontaminantsareconstantlyemerging,andthereforethetechnologymustbeconstantlyimprovedtokeepup

withpresentconditionsinsupplynetworks.Regulationsaffectingwatertreatmentandsupplyarealsopronetochanging,

resultingintheneedtoupdatetechnology.Therefore,long-term,holisticandflexiblestrategiesforimprovingwater

managementschemesaregenerallybetterthanone-timechanges.

Forexample,frequentlyneglectedinthedesignofinterventionsforwaterlossreductionisthedynamicnatureofwater

lossesandtheinteractionsofitscomponents.Manywater-lossreductionstrategiestendtofocusononepartofthesystem,

insteadofthenetworkasawhole.Efficiencyofawaternetworkatanymomentisthecombinedresultofitsnatural

deteriorationandthemeasuresthathavebeenputinplacetocombatthisdeterioration.Ifnothingisdone,therewillbe

anacceleratedproliferationofleaksandoccurrencesofdefectivewatermeters,aswellastheaccumulationofout-of-date

informationinthecustomerandnetworkdatabases.However,ifshort-termfixesareputinplaceandnotmaintained,

thesameresultcanoccur.Tosustainthegainsofwaterlossefficiency,thereshouldbeatendencytomoveawayfrom

short-terminterventionstowardsmulti-yearinvestmentplans,fundedthroughthewaterutilities’watertariffstructure,and

operationsshouldberefocusedtowardsthedesiredoutcome.

Thisgradual,dynamicapproachisalsopreferableforbuildingareputationandgainingpublictrust.Itisoftenmore

effectiveandsustainabletoworkslowlyandmakesteadyimprovementstobecomefirstinclass.Tobuildupagood

reputation,itisimportanttochooseandimplementsafeandreliabletechnologicalsolutions,andtoutilisegood

communication,committedandcapacitatedpersonnel,andsolidorganisationalprocedures.Utilitiesshouldtakecareand

ensurethesafetyofwaterwithmultiplebarriersandredundancies,asoneincidentcandestroyagoodreputationbuiltover

yearsofhardwork.

8.7 ENVIRONMENTAL PRIORITIES

Futuretechnologiesshouldbewellmanufactured,environmentallyfriendlyandenergyefficient.Soundengineeringpractices

shouldbemadeapriority,withtheaimtorespecttheenvironment.Thisincludesconsuminglessenergy–iftheyare

consumingconventionalenergyresources(gasoline,coal,naturalgas)–ordirectlyusingalternativeenergyresources(solar,

hydro,wind,biomass,etc.).Forexample,desalinationtechnologiescanbehighlyenergyconsuming;heatmustbeusedfor

waterevaporationinthermaldesalination,andelectricenergyisfundamentalinpumpingsystemsforRO.Harnessingthe

powerofrenewable,non-pollutingenergysourceswouldmakedesalinationamoresustainableresourceoption.Inthe

future,waterprofessionalswillbemoreawareofnewsustainabletechnologies.

Importantdecisionsregardingwaterandtheenvironmentshouldalsobemadewithlong-termsustainabilityinmind,

ratherthanshort-termgoalsorvestedinterestsofpoliticiansandbusinessleaders.Forexample,governmentsmaywishto


strengthentheirtieswithparticularlyinfluentialindustriesbymakinghastydecisionsthatmaynotbeinthepublic’sbest

interestinthelong-run.Thismayincludegivingfinancialsupporttohighpollutingcompanies,orselectinginfeasibleprojects

asaresultoflobbyingthatwillbetooexpensivetomaintainorevenfinishinthefuture.Companiesmaymakedecisions

thatarenotsustainableinthelong-runbasedonshort-termprofits.

Notonlymustdecisionsbemadewiththeenvironmentandsustainableresourceuseinmind,butregulatorsmusthave

thewillingnessandthecapacitytoputinplacehighfinesfornon-compliancewithpoorpractices.Iffinesaretoolow,

industriesmayfinditcheapertopayratherthanaltertheirpractices.Finesandtaxesshouldforceashiftintheway

companiesviewpolluting.


9 CONCLUSIONSOpportunitiesandneedsforimprovementarepresentinglobalwatermanagementstrategies.Theeffectsofclimatechange,

populationgrowth,over-consumptionandpollutionaretakingatollonourexistingresources,andweneedtoadapttheway

wethinkaboutandusewaterifwehopetocreateaneffective,efficient,reliableandresilientsupplyforthefuture.Allover

theworld,thesechangesarebeginningtooccur.Theresearch,trendsandcasestudiespresentedinthisCompendium

offerproofthatAWRareincreasinglybecomingincorporatedintowaterportfolios,anddisplaythebenefitsofadoptingsuch

practices.

Existingsolutionsrangeintheircosts,accessibilityandenergyefficiency.Mostdemand-managementstrategiestendto

berelativelylowcost,andsincetheyaimtoreducewaterproduction,theyactuallyreducestrainonwaterresources.RWH

isan–almost–energy-neutralandlow-costpracticethatcanbeusedalmostanywherethathassufficientprecipitation.

OtherAWRs,suchasreuseordesalination,aresaidtohavenearlimitlessquantities,butrequireenergyinproductionand

maybeexpensiveorproduceeffluentthatmustbedisposedof.Therefore,acomprehensiveunderstandingofthewater–

energynexusisneededinmakingdecisionsaboutAWRoptions,andintegrationofclean,renewableenergysourcesshould

beincorporatedintoprojectsasmuchaspossible.

Whicheverresourceoptionsareselectedforagivenscenario,itisessentialtotailorthemtothespecificlocationina

holistic,integratedfashion.Noonesolutioncanbegloballyapplicable,soitisuptowatermanagersandpoliticalleaders

–inconsultationwithrelevantstakeholders–toselectsolutionsthatsuittheregioninquestion,workwellinconjunction

andtakeintoaccountthesocial,economic,political/institutional,andenvironmentalfactorsofthearea.Doingsohasthe

potentialtocreateasafeandreliablewatersupply,whileminimisingunintendedconsequencesonenvironmentalsystems

andincreasingthesocio-economicwell-beingofthepopulation.

Ofcourse,watermanagementsectorsstillhavealongwaytogobeforeAWR-inclusiveportfolioscanbeglobally

implemented.Significantgapsexistinrelatedsectors,sobetterplatformsmustbecreatedonwhichexpertscancollaborate

toimprovenotonlytherobustnessofthetechnologybutalsoitsaccessibilityandsustainability.Enhancingthevisibilityof

successfulAWR-centredprojectsthroughconferences,mediaoutletsanddocumentssuchasthisCompendium,the

scientificcommunityandthegeneralpublicalikemaynotonlygrowtoacceptAWRpractices,butdemandthem.

55 AlternAtiveWAterresourcescluster

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