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Drinking Water Inspectorate | 55, Whitehall | London | SW1A 2EY | Tel: 020 7270 3370

http://www.dwi.gov.uk

Drinking Water Inspectorate | Ergon House, Horseferry Road | London | SW1P 2AL | Tel: 0300 068 6400

www.dwi.gov.uk

PB 13778

Drinking water2011Public water supplies in WalesJuly 2012A report by the Chief Inspector of Drinking Water

Drinking water 2011

Public water supplies in W

ales

Dr ink ing wate r in Wales

1

Drinking water in Wales 2011

Dr ink ing wate r 2011

2

Publ ished by

Dr ink ing W ater Inspectorate

Area 4a

Ergon House

Horseferry Road

London

SW 1P 2AL

Tel: 0300 068 6400

Website: http: / /www.dwi.gov.uk

© Crown Copyr ight 2012

ISBN: 978-1-905852-65-9

Copyr ight in the typographical arrangement and des ign rests wi th the Crown.

This publ icat ion (exc luding the logo) may be reproduced f ree of charge in any

format or medium provided that i t is reproduced accurate ly and not used in a

misleading context . The mater ia l must be acknowledged as Crown copyr ight wi th

the t i t le and source of the publ icat ion spec if ied.


3

Contents

Overview of drinking water qual ity in Wales 4

Water supply arrangements 9

Drinking water qual ity test ing 10

Drinking water qual ity results 12

Microbiological quali ty 12

Chemical qual ity 23

Maintaining water qual ity in distr ibut ion 36

Maintaining water qual ity at the tap 42

Drinking water qual ity events 46

Technical audit act iv ity 49

Annex 1: Further sources of information 56

Annex 2: Glossary and descript ion of standards 57

Annex 3: Drinking water qual ity events in Wales 70

Annex 4: Planned drinking water quality improvements 74

Annex 5: Compet it ion in the water industry 77

Annex 6: Water company indices 79

Annex 7: Information relat ing to public water suppl ies 84

published by the Inspectorate in 2011

Annex 8: Distr ibut ion of private water supplies 86

Dr ink ing Water 2011 is the annual repor t o f the Dr ink ing Water Insp ecto rate and

compr ises reports cover ing publ ic and pr ivate water suppl ies .

Publ ic suppl ies – Th is par t descr ibes dr ink ing water qual i ty in Wales . The Inspectorate

a lso publ ishes a ser ies of companion reports for reg ions of England (Centra l and

Eastern, London and South East , Northern, and Western reg ions) .

Pr ivate suppl ies – A summary of in format ion on pr ivate water suppl ies i s reported fo r

Wales.

Al l par ts are avai lab le on the Inspectorate ’s websi t e www.dwi .gov.uk


4

Overview of drinking water quality in Wales

Drinking Water 2011 is publ ished as a series of seven reports, f ive of

which cover publ ic water suppl ies and two descr ibe pr ivate water suppl ies.

Each report presents information about dr inking water quality for the

calendar year of 2011.

The improving national trend in the qual ity of public water suppl ies since

1990 is shown in Figure 1. Compliance with the standards in the EU

Drinking Water Direct ive now stands at 99.95% for publ ic suppl ies in

Wales, however, the results for private water suppl ies in Wales are of

concern with 8.4% of tests fail ing to meet the standards in 2011.

Figure 1: Percentage of tests from public and private supplies fail ing

the drinking water standards – England and Wales combined

0

1

2

3

4

5

6

7

8

9

10

Perc

enta

ge o

f t

ests

faili

ng

England and Wales public supplies England and Wales private supplies (data not available before 2010)

Footnote : Pub l ic supp l i es : percentage o f tes ts fa i l ing is ca lcu la ted fo r samples taken in zones .

Pr iva te supp l ies : percentage o f tes ts fa i l ing is ca lcu la ted fo r a l l samples .

At the end of 2010, the regulat ions cover ing both public and private water

suppl ies were changed to address def ic iencies in t he transposit ion of the

Drinking Water Direct ive into nat ional law . The infract ion case by the

European Commission was subsequently closed in September 2011. The

purpose of the 2010 amendments to the regulat ions was twofold: to make

enforcement mandatory for failures of standards in public buildings ; and

to make clearer the duty to minimise disinfect ion by -products. In 2011,

across Wales, companies carr ied out 3,580 tests at publ ic bui ldings out of

which only two failed to comply with one or more of the st andards or

indicator parameter values (1 lead; 1 nitr ite). On investigation these


5

failures were not attr ibutable to the bui lding water system and it was not

necessary therefore for the water company to require any improvements to

be made by the publ ic bui lding owner. For detai ls about these failures in

public buildings in Wales see the Maintaining water quality at the tap

section.

In relat ion to how well companies are complying with the requirement to

keep disinfect ion by-products as low as possible, in 2011 across Wales,

the annual average f igure for total tr ihalomethanes was 8.9µg/l in

groundwater suppl ies and 32.3µg/l in surface water inf luenced suppl ies,

compared to the standard of 100µg/l. For more information about

tr ihalomethanes in Wales see the Chemical qual ity – Disinfect ion by-

products section .

This report describes the key facts about the quality of public water

suppl ies in Wales, which is served by f ive water companies, supplying

water to almost three mil l ion consumers. In addit ion, local authorit ies in

Wales have identif ied 17,718 private water suppl ies and the detai ls of the

quality of these pr ivate suppl ies can be found in the separate report

Drinking Water 2011 – Private water suppl ies in Wales. Annex 8 of this

report maps the location of private suppl ies reported to the EU under the

Drinking Water Direct ive. I t also shows small shared suppl ies used only for

domestic purposes.


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The results of the test ing of public suppl ies in 2011 demonstrated that

the overal l qual ity of drinking water in Wales was satisfactory. The f igure

for compliance with drinking water standards at consumers’ taps was

99.95%, down from the f igure of 99.96% reported in 2010 and below the

industry average. This f igure is made up of the results of all the tests for

39 parameters with European or national standards. Across Wales

al l tests for 31 out of 39 parameters gave satisfactory results. Fai lures

were recorded for odour, taste, nitr ite, aluminium, iron, manganese, lead

and bromate.


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Table 2 puts the failures into context with respect to the regions

of England.

Table 2: Parameters exhibiting one or more failures of a standard

Parameters Wales

England

Central

and

Eastern

region

London

and South

east

region

Northern

region

Western

region

Microbiological parameters

E.col i

Enterococc i

Physical/chemical parameters

Odour

Taste

Aluminium

I ron

Manganese

Lead

Turbid i ty

Nickel

Benzo(a)pyrene

Copper

Ni tr i te

Bromate

Chlorto luron1

Clopyral id1

Glyphosate1

MCPA1

MCPP1

Metaldehyde1

Propyzamide1

1These parameters are pest ic ides.

When Wales is judged by the Inspectorate’s four indices of water quali ty

performance, which look in turn at water t reatment (covered by two

indices, process control and disinfect ion), service reservoir integrity and

network maintenance, in 2011 there was improvement for disinfect ion

(99.95%). The following indices were all l ower than last year; process

control (99.97%), reservoir integrity (99.96%) and network maintenance


8

(99.72%). Al l indices were below the industry f igure except for reservoir

integrity. Individual water company f igures are reported in Annex 6 .

Across Wales there were fewer events af fect ing water quality overall

(25 compared to 37 in 2010). None of the events were major or serious,

however, approximately one-quarter were of a type that necessitated a

detai led invest igation by an inspector and this compares favourably with

the industry overal l. The number of each event type can be found in the

Drinking water qual ity events sect ion with learning points f rom other event

assessments by the Inspectorate. In 2011, it was necessary for the

Inspectorate to take enforcement act ion at Llwyn Onn works, Legacy works

and the Wrexham ring main in relat ion to an event that occurred in 2010 in

North East Wales in the area supplied by Dee Val ley Water . Notable

events with wider learning points are described in the Drinking water

quality events sect ion. Companies serving Wales are legal ly required to

complete the work summarised in Annex 4 during the AMP5 period (2010–

2015).

In 2011, the Inspectorate provided the water industry with advice and

guidance on nine topics to enable companies to comply with the drinking

water regulat ions. In addit ion, nine research projects were publ ished by

the Inspectorate to support the industry in carrying out regulatory r isk

assessments (see Annex 7).


9

Water supply arrangements

Five water companies supply dr inking water in Wales: Albion Water (ALB),

Dee Val ley Water (DVW), Dŵr Cymru Welsh Water (DWR) , Severn Trent

Water (SVT) and SSE Water (SSE). Severn Trent Water mainly suppl ies

consumers in England, but it is included here because it also suppl ies

water to consumers in the central eastern area of Wales. In 2011, SSE

Water (SSE) became a new licensed supplier in Wales and serves 46

consumers in Llani l id Park, Bridgend. The company has purchased a bulk

supply of water f rom Dŵr Cymru Welsh Water.

Much (93%) of the water suppl ied to consumers in Wales is surface water

abstracted f rom rivers such as the Dee, Taff , Severn, Towy and Wye.

The upland areas of Wales are important catchments for water resources.

Water is drawn from many reservoirs including the Alwen, Elan, Taff

Fechan and Vyrnwy, some of which also supply consumers in England.

For example, the Elan reservoir suppl ies the city of Birmingham and the

Vyrnwy reservoir suppl ies consumers in North Cheshire and Merseyside.

Across Wales, a small proport ion (6%) of water suppl ies come from

groundwater sources.

Figure 3: Map il lustrating sources of drinking water by zone across

Wales


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Private water suppl ies in Wales are widely distr ibuted across the country

(see Annex 8). These private suppl ies are sl ight ly more reliant on

groundwater (9%) than are the public suppl ies (6%).

Summary facts about the drinking water supply infrastructure in Wales are

given in Table 4 with outl ine geographical and demographic information.

Table 4: Key facts about public and private water supply arrangements

in Wales

Public supplies Private supplies

Population supplied Water supplied (l/day) Abstraction points Treatment works Service reservoirs Water supply zones Length of mains pipe (km)

2,994,346 822 million 89 88 630 101 31,110

Population supplied Water supplied (l/day) Approximate number of private water supplies Total number of local authorities

70,454 100 million

17,718

22

Water composition

Surface sources Groundwater sources Mixed sources

93% 6% 1%

Water composition

Surface influenced supplies Groundwater sources Rainwater

91% 9%

0.1%

Area of public supply

Anglesey, Blaenau Gwent, Bridgend, Caerphilly, Cardiff, Cardiganshire, Carmarthenshire, Conwy, Denbighshire, Flintshire, Gwynedd, Merthyr Tydfil, Monmouthshire, Neath and Port Talbot, Newport, Pembrokeshire, Powys, Rhondda Cynon Taff, Swansea, Torfaen, Vale of Glamorgan, Wrexham County Borough.

Number of local authorities with private supplies

22

Drinking water quality testing

Throughout 2011, water companies sampled drinking water across Wales

to test for compliance with the drinking water regulat ions. Almost one-third

(31%) of the tests were carr ied out on dr inking water drawn from

consumers’ taps selected at random. For monitor ing purposes, company

water supply areas are divided into zones . Sampling in zones at

consumers’ taps is r isk based with the number of tests being higher in

zones with a large populat ion (maximum 100,000). Other sample locations

are water treatment works and treated water (se rvice) reservoirs.

Collect ively, the f ive water companies carr ied out a total of 342,608 tests

during 2011. Only 99 of these tests failed to meet the standards set down

in the regulat ions or exceeded screening values .


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Table 5: Number of tests carried out by companies in Wales

Company

Place of sampling

Number of

tests per

company

Estimate

of

populat ion

Water

treatment

works

Service

reservoirs

Consumers’

taps

(zones)

Albion Water

0 (0)

0 (0)

601 (1)

601 300

Dee Val ley Water

8,429 (4)

9,204 (29)

8,361 (13)

25,994 160,000

Dŵr Cymru Welsh Water

77,180 (77)

111,509 (453)

93,374 (77)

282,063 2,778,000

Severn Trent Water

5,776 (2)

22,764 (58)

5,071 (9)

33,611 56,000

SSE W ater 0

(0) 0

(0) 339 (1)

339 46

Wales overall

91,385 (83)

143,477 (540)

107,746 (101)

342,608 2,994,346

Numbers in b rackets re f lec t the number o f works , reservo i rs or zones operated by that company

in W ales in 2011. Some companies are pe rm i t ted to car ry out some tes ts on samples taken f rom

suppl y po in ts ra t he r than f rom consumers ’ taps .

The regulat ions require companies to test for specif ied parameters at

prescribed f requencies. Most of the test ing is f or parameters with

European or national standards, however, water companies are also

required by the regulat ions to test for other par ameters, such as

ammonium, sulphate and colony counts.

A summary of the results of test ing by compan ies for each parameter

can be found on the Inspectorate’s website (www.dwi.gov.uk) and on the

CD accompanying this report. Addit ionally, the Inspectorate publ ishes

the performance indices for each company in Annex 6 annually.


12

Drinking water quality results

The key water quality results for Wales in 2011 are presented in two

tables, one showing the results for microbiological parameters (Table 6),

the other deal ing with chemical and physical parameters (Table 13). The

microbiological quali ty of water is discussed f irst. Companies report al l the

results of the tests on a monthly basis to the Inspectorate. Also, tables in

Annex 6 describe the drinking water qual ity performance indices of each

company supplying Wales.

Microbiological quality

To protect public health, microbiological standards have to be met at each

individual treatment works and service reservoir. The signif icance of the

individual test results for each microbiological parameter at each locat ion

var ies and a single posit ive result cannot be interpreted without other

information. Al l companies are expected to follow best pract ice for

sampling and investigations as set out in The Microbiology of Drinking

Water published by the Standing Committee of Analysts (SCA) which can

be found by visit ing the Environment Agency’s website (www.environment -

agency.gov.uk).

Table 6: Microbiological tests The number of tests performed and the number of tests not meeting the standard

Parameter Current

standard

Total number of tests

Number of tests not meeting

the standard

Addit ional information

Water leaving water t reatment works

E.col i 0/100ml 12,690 1 DVW (1)

Col i form bacter ia 0/100ml 12,690 10 DVW (1) DWR (6) SVT (3)

Clostr id ium per fr ingens

0/100ml 4,993 6 DWR (6)

Turbid i ty1 1NTU 12,689 12 DVW (6) DWR (6)

Water leaving service reservoirs

E.col i 0/100ml 23,904 0

Col i form bacter ia

0/100ml in 95% of tes ts

at each reservoir

23,904 18

DWR (11) SVT (7) Al l reservoirs in Wales meet the 95% compl iance ru le

Water sampled at consumers’ taps

E.col i 0/100ml 7,934 0

Enterococc i 0/100ml 664 0 1Turb id i ty is a cr i t ica l contro l parameter for wate r t reatment and d is in fect ion.


13

E.coli at works and service reservoirs

In 2011, a total of 12,690 tests at works and 23,904 tests at service

reservoirs were carr ied out by al l the companies across Wales. E.col i was

detected in only one sample at Boughton works in 2011. This represents

an improvement compared to 2010 when there were three recorded failures

in total ( two works, one service reservoir) .

Table 7: Detection of E.coli and Enterococci at treatment works,

service reservoirs and consumers’ taps

Company

E.coli in water

leaving treatment

works

E.coli in water

leaving service

reservoirs

E.coli at consumers’

taps

Enterococci at

consumers’ taps

Albion W ater 0 – 0 0 – 0 0 – 12 0 – 4

Dee Val ley Water

1 – 1 ,147 0 – 1 ,534 0 – 482 0 – 97


0 – 10,718 0 – 18,576 0 – 7 ,278 0 – 542

Severn Trent Water

0 – 825 0 – 3 ,794 0 – 155 0 – 19

SSE W ater 0 – 0 0 – 0 0 – 7 0 – 2

Wales overall 1 – 12,690 0 – 23,904 0 – 7 ,934 0 – 664

Note: Resu l ts are shown as the number o f pos i t i ve t es ts – the to ta l number o f tes ts .

On detect ing E.col i, companies are required to act promptly to protect

public health. The immediate response when f inding E.coli at a works is

to sample again, and more widely, to conf irm that water being received

by consumers is safe.

In June, E.col i was reported in a sample col lected by Dee Val ley Water

f rom Boughton works in Chester, serving consumers in North East Wales

and also parts of England (Northern Region). The company notif ied the

Inspectorate of an event (see Annex 3 and the Dr inking water qual ity

events section) and carr ied out an immediate investigat ion involving

samples f rom the key process stages at the work s, including on-site

treated water storage and from the distr ibut ion system. This sampling

survey conf irmed that water in Boughton water tower was contaminated

with E.coli and the company removed it f rom supply (see Figure 8). The

Inspectorate was very cr it ical of the fact that the company had ident if ied

integrity problems with the tower in January and had been chlorine dosing

the tower over a number of years following a previous detect ion of E.col i

in August 2005. A previous audit had been undertaken by the Inspectorate

in 2006 who had expressed doubts about the f itness for purpose of the

tower. The Inspectorate has repeatedly advised companies that manual

dosing of sodium hypochlorite (disinfectant) is a short-term measure


14

that should never be used as a subst itute for remediat ion of structural

or other integrity faults with service reservoirs and towers.

The company has since ident if ied the fol lowing principal water quality

hazards in its r isk assessment for Boughton water tower; a complete loss

of the reservoir due to structural fai lure, failure of the roof ’s integrity and

contamination of water with animal excrement and gnaw damage to the

infrastructure. The company has specif ied a number of control measures to

mit igate these r isks, including regular inspections of the tower and its roof ,

continuous manning of the works, chlor ine and f low monitor ing, the abil i ty

to bypass the reservoirs, engineer ing controls, a maintenance schedule

and a competent operator scheme. The Inspectorate was very disappointed

about the length of t ime the company has taken to put in place permanent

solut ions to mit igate against these known risks. The tower was taken out

of service and enforcement act ion was taken. A Notice has been in place

since March 2012 to ensure that the company carr ies out appropriate

remediat ion within agreed t imescales to protect publ ic health.

In September, as a part of the Inspectorate’s r isk -based programme of

technical audit , the works and tower were vis ited and a number of further

def iciencies were highlighted (see the Technical audit act iv ity sect ion).

The company was required to further revise its r isk assessment for the

site. The water tower wi l l not be returned to service unti l Dee Val ley Water

has completed al l remedial act ions.

Figure 8: Using scaffolding to make repairs to Boughton water tower


15

Coliform bacteria at works

Testing for coliform bacteria gives reassurance that water entering the

supply was treated adequately to remove bacterial and viral pathogens.

Repeated occurrences of coliform bacteria in samples f rom the same

works in one year are thus of concern and require act ion to be tak en.

During 2011, col iforms were detected twice , in May and October , in

samples collected f rom Bretton works in North Wales operated by Dŵr

Cymru Welsh Water. In response to the f irst failure , the company replaced

the sample tap because improvements in its location were deemed

necessary following refurbishment of disinfect ion at the site in 2010, as

required by a Not ice issued by the Inspectorate. However, af ter the second

failure, Dŵr Cymru Welsh Water reviewed the operation of the works and

performance issues with the granular act ivated carbon f i l ters (elevated

turbidity af ter backwashing) . The company altered the backwashing regime

for the f i l ters by increasing the volume of r inse water and adjust ing the

outlet f i l ter valves to prevent r inse water entering supply . Addit ional ly, the

company moved the location of the new sample point and replaced the roof

membrane of the treated water tank. All subsequent tests have given

satisfactory results. Companies are reminded that the cause of coliform

failures at works can be l inked to the operation and maintenance of

granular act ivated carbon f i l ters and this potential cause should be

investigated promptly following guidance publ ished in 2009: Validating the

cause of col iforms in drinking water (DWI70/2/229).

In January 2011, at Alwen works, near Betws-y-Coed in North Wales,

col iform bacteria were detected in a sample col lected by Dŵr Cymru Welsh

Water. Another col iform failure had occurred previously in September

2010. The Inspectorate reported in Drinking Water 2010 , that a Notice had

been put in place to restr ict the output volume of Alwen works unti l such a

t ime as all necessary improvements to the dis infect ion process had been

completed. The planned improvements to enable changing the dis infect ion

process f rom chloramine to f ree chlor ine were completed ahead of

schedule in February 2011 and all subsequent tests have given

satisfactory results. Figure 9 i l lustrates the improvements made to the

contact tank arrangements to secure adequate dis infect ion. Baff les have

been added to slow the progression of water through the tank and increase

the contact t ime with chlor ine.


16

Figure 9: Flow patterns in the existing contact tank at Alwen works

before and after installation of baffle walls to aid mixing

Coliforms were detected in February at two unrelated works (Capel Dewi

works in Carmarthen and Cray works in the upper Swansea val ley) in

South Wales in samples collected by Dŵr Cymru Welsh Water on the same

day. The company audited both treatment works and found nothing

untoward. For example, raw water quality had been in the normal range

and both works were operating effect ively in the t ime precedin g the

failures. The company extended the investigation to the qual ity control

procedures at the laboratory and found no signif icant issues with the

analysis. The company has since implemented large volume investigatory

sampl ing at both sites and to date the results have all been satisfactory.

In June, col iform bacteria were detected at Llandegfedd Works in South

East Wales. Also, on two occasions in February and once in November ,

the company reported Clostr idium perfr ingens in samples. As a result of

the col iform failure in June, Dŵr Cymru Welsh Water cleaned out the two

treated water tanks on site and repaired possible points of ingress in one .

The disinfect ion on site was being operated as marginal chlor ination

(contrary to its design) because a previous health and safety inspect ion

had ident if ied a potential bui ld up of toxic gases in the basement area

where the dechlorination equipment is located. The pract ice of

dechlor inat ion had been halted on grounds of operator safety. The

Inspectorate has noted that the company ’s decision making did not

consider the r isk to water qual ity. Any change to water treatment should

identify the r isks to both water qual ity and the safety of workers and act ion

should not compromise one at the expense of the other. This works is the

subject of major refurbishment due to be completed in 2012. During 2011,

14 out of 28 f i l ters were refurbished with new media instal led. Similar work

to the remaining f i l ters was completed in February 2012. The disinfect ion

system wil l be reinstated to normal operation on complet ion of these

maintenance works.


17

In August, col iform bacteria were detected at Shelton works near

Shrewsbury (Oswestry main) The works treats both groundwater and

surface water f rom the River Severn and is operated by Sever n Trent

Water. The works is located in England (Central region) f rom where it

suppl ies parts of Shropshire in England, and also Fl intshire and

Denbighshire in Wales. The company ’s investigat ion found no process

performance issues. Fol lowing a turbidity fai lure in 2010, the sampling

facil i t ies at the works were considered unsuitable being located outside

and open to the elements. Severn Trent Water have since replaced the

sample tap and modif ied their sampling procedures.

The Inspectorate has noted that col i form bacteria were found in 10

samples f rom treatment works in Wales during the year compared to eight

in 2010 and this information wi l l be taken into account during the

Inspectorate’s r isk -based programme of technical audit .

Clostridium perfringens

This organism is a spore-forming bacterium that is exceptional ly resistant

to unfavourable condit ions in the water environment , such as extremes of

temperature and pH, and disinfect ion processes such as chlor inat ion and

ultraviolet l ight. I t is a normal component of the intest inal f lora of up to

35% of humans and other warm-blooded animals. These characterist ics

make it a useful indicator of either intermittent or historical f aecal

contamination of a groundwater source or the performance of a surface

water f i l t rat ion plant . The detect ion of any Clostr idium perfr ingens should

tr igger an invest igation by the water company.

In 2011, three out of 4,993 samples col lected in Wales did not meet the

specif ied value and al l were f rom one works, Llandegfedd operated by Dŵr

Cymru Welsh Water in South East Wales . This site was the subject of

major improvement works during 2011 involving refurbishment of the rapid

gravity f i l ters. In addit ion to the detect ions of Clostr idium perfr ingens ( two

in February, one in November) , there was one col iform failures (see the

Coliform bacteria at works sect ion). At the t ime of the failure in November

there was a small increase in raw water demand with six out of 28 f i l ters

out of service. The Inspectorate expects companies to careful ly m onitor

the performance of all f i l ters to ensure that these are operat ing in an

effect ive and optimised manner under the full range of raw water quality.

Such monitor ing is part icular ly cr it ical when more than the usual number of

f i l ters are out of service for maintenance.

In 2011, across Wales there were three detect ions of Clostr idium

perfr ingens at consumers’ taps in March (Conwy), July (Bryncrug) and

September (Cardif f East). In each case, Dŵr Cymru Welsh Water attr ibuted

these failures to the condit ion of the consumer ’s tap or to minor


18

contraventions of the Water Supply (Water Fit t ings) Regulat ions 1999 . The

failure within the Cardif f East zone was considered as being related to the

potent ial for back-siphonage between the kitchen mixer tap and a washing

machine. The company required modif icat ions to the plumbing a nd

subsequent water tests were sat isfactory. The Inspectorate expects

companies to fol low its guidance published in 2009 that monitoring for this

indicator parameter should be appropriate to its purpose, with test ing at

consumers’ taps being l imited, and only for the purpose of making up the

balance of the sample f requency set out in the EU Drinking Water

Direct ive. The Inspectorate is pleased to note that other companies have

since amended their monitor ing programmes (see the Microbiological

quality – Clostr idium perfr ingens sect ion in the Drinking water 2011

London and South East region).

I f monitoring is carr ied out at consumers’ taps then the invest igation must

involve a check of the eff iciency and performance of water treatment at the

supplying works. In al l three cases, the company fai led to carry this out in

their init ia l investigation , therefore attr ibut ion to the consumers’ taps

cannot be regarded as conclusive.

Turbidity at works

Turbidity is a measure of how much l ight can pass through water and

indicates the condit ion or ‘cloudiness ’ of water. Turbidity is caused by

part ic les suspended in the water and is an important cr it ical control

measure of the performance of disinfect ion. Turbidity is measured at two

points in the water supply chain, at treatment works where a value of

1NTU appl ies and at consumers ’ taps where the standard of 4NTU appl ies.

The following discussion focuses on the results of sa mples taken at

treatment works.

In 2011, there were 12 occasions, out of a total of 12,689 tests, when a

value in excess of 1NTU was recorded in water leaving a treatment works

in Wales (6 DVW, 6 DWR). This compares favourably with 2010 when 22

unsat isfactory results were reported f rom a total of 13,005 tests.

Each value of >1NTU was a single occurrence with the exception of

Legacy works operated by Dee Val ley Water which exhibited f ive fai lures

between Apri l and October. There is a legally binding programme of work

at Legacy works for Dee Val ley Water to review the need to improve

manganese removal at the works by March 2013. In accordance with this

Notice the company has already instal led a stat ic chemical mixer at s ite

to improve pH control , manganese removal and reduce turbidity of the

works ’ output .


19

The company has also instal led new nozzles in the f i l ters to improve their

backwashing performance and hence reduce turbidity post -f i l t rat ion see

Figure 10).

Figure 10: New filter nozzles in one fi lter bed before it was returned to

service in September 2011

The company attr ibuted the turbidity fai lures to a variety of causes, such

as the sample tap and changes in f low, however, al l occurred following

renovat ion of the granular act ivated carbon f i l ters and release of

manganese deposits is the more probable explanation. Part ic les in the

fail ing turbidity samples were examined microscopically and staining tests

reacted strongly for manganese. The act ions being taken by the company

to signif icant ly improve the removal of manganese at the site are expected

to resolve recurrent turbidity failures.

Dŵr Cymru Welsh Water has improved treatment works turbidity

performance in 2011 with six recorded values >1NTU compared to 18 in

2010, ref lect ing the benef it of recent investment in water treatment by the

company, for example, at Cwellyn works (Figures 11 and 12).


20

Figure 11: Improvements to Cwellyn under construction in 2009

Figure 12: The completed refurbishment at Cwellyn in 2011


21

The Inspectorate was disappointed to note that more than 50% of the

turbidity failures in 2011 were f rom sites with a history of such problems,

indicat ive of the industry’s general lack of due care and attent ion to this

important operat ional parameter.

Coliform bacteria at service reservoirs

Testing for coliform bacteria gives reassurance that the qual i ty of water

held at these strategic points in the distr ibut ion system is adequately

maintained. The national standard requires that at least 95% of no less

than 50 samples collected f rom each service reservoir throughout one year

are f ree f rom all coliform bacteria. In 2011, al l service reservoirs ( including

water towers) in Wales met this standard, however, there was a

deteriorat ion in service reservoir performance as ref lected by a r ise in

col iform failures to 18 in 2011 (11 DWR), (7 SVT) compared to 13 in 2010

(1 DVW, 10 DWR, 2 SVT). The main reason for this decline in performance

for Wales as a whole was results f rom service reservoirs owned by Severn

Trent Water.

During 2011, Severn Trent Water found col iform bacteria in samples taken

from seven service reservoirs dur ing 2011. These were dif ferent reservoirs

to the two found to contain coliform bacteria in 2010. The following service

reservoirs in Wales operated by Severn Trent Water contained col iform

bacteria: Talerddig New (Apri l) ; Dolfor New service (September); Bryn

Berriew (September) ; Aberhosan (October) ; Black Hi l l (Upper Dolfor)

(November); Bausley and Llanfyl in (December).

A number of these service reservoirs are small with poor turnover. The

Inspectorate notes with concern the uncontrol led manual dosing of chlorine

at Bryn Berr iew service reservoir (recorded value of 1.47mg/l free residual

chlorine compared to a target of 0.2mg/l). The Inspectorate does not

approve of uncontrol led manual dosing of chlor ine as a means of achieving

microbiological standards in a distr ibut ion system where there are known

issues with system design, maintenance and management arrangements .

Across Severn Trent Water’s supply area (both in Wales and England) ,

col iform bacteria were detected at 25 service reservoirs in 2011 and the

Inspectorate judged that the heightened r isk of ingress of faecal

contamination was unacceptable, accordingly enforcement act ion was

init iated and a legal ly binding programme of planned and reactive

inspect ions, and also maintenance, is now in place to ensure al l reservoirs

are inspected within a 10-year period. So far as is pract icable , the

company wil l complete al l necessary repairs at the t ime of each inspect ion.

Llysfaen (small) service reservoir in Conwy , North Wales operated by Dŵr

Cymru Welsh Water was found to contain col iform bacteria during October.

The company took the service reservoir out of supply to carry out an


22

inspect ion. The reservoir was f lood tested and cleaned and no defects

were found. All subsequent results have proved satisfactory.

At Rhiwbina service reservoir Cardif f , following a col iform failure in July ,

Dŵr Cymru Welsh Water drained, inspected and cleaned both cel ls, they

also identif ied a need to improve the sampling arrangements. The site is

subject to a Notice to address ingress at the site with al l work due for

complet ion by March 2015.

At Maesol Service reservoir, Llangernyw, North Wales in October the

investigation of a col iform failure by Dŵr Cymru Welsh Water identif ied a

problem with chlor ine residual management at the upstream Bryn Cowlyd

works. This had not been adjusted to take account of the warmer autumn

weather. Adjustments were made and al l tests have since given

satisfactory results. The Inspectorate expects companies to proactively

review arrangements for the maintenance of water qual ity within the

network.

The Inspectorate has noted that col iform bacteria were found in 18

samples f rom service reservoirs in Wales during 2011 and in most

instances this was due to a lack of maintenance of either the structure or

the sampling facil i t ies. The Inspectorate wi l l be examining the r isk

assessment methodology of companies in Wales to ensure it is adequate

in relat ion to service reservoir and distr ibut ion maintenance.

E.coli and Enterococci at consumers’ taps

Like E.coli , the presence of Enterococci is indicat ive of faecal

contamination and neither of these bacteria should be found in any

sample. In 2011, the companies carr ied out 8,598 tests for E.col i and

Enterococci at consumers’ taps and all tests gave sat isfactory results .

The Inspectorate is pleased to acknowledge the good record for

microbiological results at consumers’ taps in Wales ( two successive years

of no failures for either indicator organism).


23

Chemical quality

The drinking water regulat ions set out the minimum test ing requirements

for all chemical and physical parameters. A f ull summary of the results of

test ing by each company, including the results for indicator parameters ,

is provided on the Inspectorate’s website and on the CD accompanying

this report.

The following text and Table 13 set out the results for those paramete rs

where there has been a failure to meet a European or national standard

(mandatory qual ity standards) and any other parameter of interest . In

addit ion, at the request of local author it ies, the results of test ing for

f luoride, iron, lead, manganese, nitra te, nitr ite, pesticides and radioact ivity

are given. New this year, the Inspectorate has included instances where

residual chlor ine results were reported at a level above that considered

desirable on grounds of consumer acceptabi l i ty (2mg/l).


24

Table 13: Chemical and physical parameters

The number of tests performed and the number of tests not meeting

the standard or screening value

Parameter

Current standard or

specified concentration

1

Total number of tests

Number of tests not meeting

the standard

4

Additional information

Aesthetic parameters

– odour No abnormal change

1,882 8 DVW (2), DWR (6)

– taste 1,627 5 DVW (2), DWR (3)

Aluminium 200μg/l 1,897 1 DWR (1)

Ammonium 0.5mg NH4/l 1,695 1 DWR (1)

Bromate 10μg/l 700 2 DWR (2)

Chlorine – residual (free)2 2mg/l 44,527 8

DVW (1), DWR (1), SVT (6)

Chlorine – residual (total)2 2mg/l 44,591 16

(DVW) 2, DWR (8), SVT (6)

Fluoride 1.5mg/l 632 0

Iron 200μg/l 2,474 10 DVW (1), DWR (9)

Lead (current standard) 25μg/l 666 3 DWR (3)

Lead (future standard) 10μg/l 666 6 DVW (2), DWR (4)

Manganese 50μg/l 1,861 6 DVW (2), DWR (4)

Nitrate 50mg/l 986 0

Nitrite 0.5mg/l 986 2 DWR (2)

Pesticides – total 0.5μg/l 660 0

Pesticide – individual3 0.1μg/l 23,408 0

pH (Hydrogen ion) 6.5 – 9.5 2,318 4 DVW (2), DWR (2)

Radioactivity

Gross alpha 0.1Bq/l 874 0

Gross beta 1.0Bq/l 874 0

Tritium 100Bq/l 579 0

Notes: 1For comparison, 1mg/l is one part in a million, 1μg/l is one part in a thousand million.

2The value of 2mg/l is a consumer acceptability value set by the Inspectorate.

3A further 2,548 tests were done for aldrin, dieldrin, heptachlor, heptachlor epoxide, all of which met the

relevant standard. 4Standard or screening value


25


Customers expect their dr inking water to be clear and bright in appearance

and free f rom discernible taste or odour. In recognit ion of this , the

regulat ions st ipulate national s tandards for colour, odour and taste.

Companies are required to investigate the cause of any adverse results.

In 2011, eight samples f rom a total of 1,882 tests exhibited a discernible

odour (DVW 2, DWR 6) and in f ive of these a taste was also recorded

(DVW 2, DWR 3).

Earthy/musty

These descr iptors relate to situat ions where object ionable tastes or odours

are caused by fungi, materials in contact with water or algae in raw water.

In 2011, three samples out of a total of 1,363 were recorded as having an

earthy or musty taste. In Apri l , Dŵr Cymru Welsh Water identi f ied a musty

taste and odour in a sample f rom a consumer’s tap in the East Anglesey

zone in North Wales. The company carr ied out a comprehensive

investigation, including checking the operation of the Cefni treatment

works and records of consumer water quality complaints. The company

also carr ied out a water f it t ings inspect ion and no def iciencies were

identif ied. There was no evidence of a wider taste or odour problem in

the zone.

Also in Apr il, Dŵr Cymru Welsh Water reported a musty taste and odour in

a consumer’s tap sample col lected f rom the Abergavenny/Cwmtil lery zone

in Mid Wales. The company checked the operat ion of Talybont works as

this had previously been ident if ied in the company’s r isk assessment

process as exhibit ing a taste and odour r isk f rom compounds found in the

raw water. As part of a legal ly binding programme of work , dif fused air

f lotat ion (DAF) has been installed to remove organic matter and improve

taste and odour in the supply to this zone.

Sulphurous taste and odour

In May, Dŵr Cymru Welsh Water identif ied water with a sulphurous taste

and odour in a sample col lected f rom the Cray/Clydach zone, South Wales.

The property was located in a cul -de-sac and the cause may have been

low f low/turnover of water as repeat samples f rom the original and

neighbouring propert ies proved satisfactory , and the company did not

identify any def ic iencies with the plumbing inside the property.

Chemical taste and odour

Dee Val ley Water detected a chemical taste and odour in a c onsumer’s tap

sample collected in September f rom the Overton water supply zone near

Wrexham. The company carr ied out an inspection at the property and


26

found no plumbing irregularit ies. A similar situation occurred in February,

when Dŵr Cymru Welsh Water reported a chemical odour in a consumer’s

tap sample collected from the Malpas/Caerleon/Cwmbran water supply

zone, however, in this case the company was unable to gain access to the

property to invest igate. In September, fol lowing a d etect ion of a chemical

odour in a consumer ’s tap sample in the Conwy zone, North Wales , Dŵr

Cymru Welsh Water investigated the treatment works , but did not carry out

a f it t ings inspection. In al l these cases a wider taste and odour problem

was not identif ied in the zone.

Unspecified taste and odour

In November 2011, Dŵr Cymru Welsh Water reported a posit ive taste and

odour without a descriptor in a sample f rom the Caerau/Ystradfellte zone

in Mid Wales. The company was unable to gain access to the property to

col lect further samples. Samples f rom neighbour ing propert ies were

satisfactory, but the company did not check the treatment works supplying

the area.

When consumers experience a persistent taste or odour, they may contact

their water company to report the problem. Records of these contacts in

each zone are recorded by water companies and passed to the

Inspectorate annually. Figure 14 maps the contact rate per thousand

people to give a picture of taste or odour issues across Wales .


27

Figure 14: Rate of taste and odour contacts per 1,000 population

The Inspectorate has observed that companies in Wales have grouped

close to half (48%) of all 1,274 taste and odour consumer contacts

received during 2012 in the report ing category of ‘other’ . While the

Inspectorate’s report ing scheme provides for an unclassif ied ‘other ’

report ing category, its purpose was intended only as a means of capturing

a genuinely unusual or unique type of contact or a situation where the

consumer refuses or is unable to answer diagnost ic quest ions. The


28

Inspectorate intends to look into this unusual prof i le of contacts during

2012.

Aluminium

Aluminium can occur natural ly in some water sources. Also, aluminium-

based water treatment chemicals may be used at surface water wo rks

to aid the process of f i l t rat ion.

In 2011, a total of 1,897 samples were tested for aluminium across Wales.

Albion Water, Dee Val ley Water, SSE Water and Severn Trent Water

achieved 100% compliance with the aluminium standard. Only one test

exceeded the standard in 2011 and this was f rom a consumer tap sample

col lected f rom the Pontypridd zone fed by Pontst ici l l t reatment works ,

operated by Dŵr Cymru Welsh Water .

In February, Pontst ic i l l t reatment works was undergoing refurbishment as

part of a legal ly binding programme of work to secure compliance with the

aluminium standard. Changes made to improve mixing at the point where

coagulant is added to raw water were completed in March 2012. The

aluminium failure in the Pontypridd zone was associated with a failure of

the manganese standard and the most probable cause was a localised

disturbance of histor ic deposits accumulated in the distr ibut ion network.

Dŵr Cymru Welsh Water has completed a detai led feasibil i ty study in

relat ion to replacement of the local trunk main and a preferred option has

been selected. This work wi l l be undertaken before the end of the AMP6

period (2020).

Ammonium

Traces of these salts occur natural ly in most environmental waters and

general ly the highest levels occur in anaerobic groundwater. Intensive

rearing of farm animals can also give r ise to high levels in surface waters.

Ammonia is a major component of mammalian metabolism , so direct

exposure f rom environmental sources has no health signif icance. However ,

ammonia can compromise water treatment (dis infect ion and f i l ters for the

removal of manganese) and its presence in water may be an indicator of

more serious bacterial, sewage or animal waste pol lut ion. Across Wales

in 2011, a total of 1,695 tests for ammonium were carr ied out and just one

exceeded the standard of 0.5mg NH4 / l (1 DWR).

In January, a value of 0.51mg NH4 / l was recorded in a sample col lected

f rom a consumer’s tap in the Holywell/Mold water supply zone suppl ied by

Dŵr Cymru Welsh Water’s Alwen works where, historical ly, pr imary

dis infect ion has been inef fect ive using chloramine rather than f ree

chlorine. In February, the company completed the dis infect ion


29

improvement works set out in a Not ice (see Figure 15). The faci l i ty to dose

ammonia has been permanent ly switched off and it is not expected that

any further failures wi l l occur in this zone.

Figure 15: The new Alwen works under construction during 2010

Bromate

Bromate is a disinfect ion by-product (DBP) and can be formed in dr inking

water if the surface water source contains bromide and ozone is used in

the treatment process. The process of chlorination may also produce

bromate, for example, through the purchase and use of an unapproved

sodium hypochlor ite solut ion containing bromide or when chlor ine is

generated on site by electrolysis. In recent years, companies have put in

place improved control measures aimed at meeting the standard of 10μg/l.

In 2011, across Wales, two out of a total of 700 tests exceeded the

standard and both samples were f rom consumers’ taps in the Pendine

Water supply zone operated by Dŵr Cymru Welsh Water .

A value of 11.7μg/l was reported in March. The company reviewed the

treatment process at Pendine works and conf irmed that approved ( low

bromate) hypochlor ite solut ion was being used for disinfect ion and al l

other treatment chemicals met the requirements of Regulat ion 31 , and al l

investigative samples at the works and in the zone proved satisfactory.


30

However, a further fai lure occurred in August and the company carr ied out

a more wide-ranging invest igation looking at the raw water sources .

Pendine works draws water f rom a borehole and this water is then pumped

into a small, open storage reservoir located above Pendine beach. For the

purpose of control l ing seasonal algal growth, the company ’s histor ic

practice was to dose this reservoir with hypochlor ite. The Inspectorate

recommended ceasing this pract ice and enhancing bromate monitor ing at

the works. Alternative methods of algal control a re being sought by the

company. For more information on DBPs see the Chemical qual ity – Disinfect ion

by-products sect ion .

Chlorine

Chlorine is widely used in households as bleach. I t is an important

dis infectant with many appl icat ions in the home and workplace wherever

the maintenance of good hygiene is necessary. I t is the most common

oxidative dis infectant used in swimming pools and there is a long history

of its use in water suppl ies stretching back for a century. Typical levels

of residual chlor ine in public water suppl ies in the UK are in the range of

0.1 – 1.0mg/l, wel l below levels typical ly found in many other parts of the

world. Human exposure to chlorine in drinking water has not been

associated with any specif ic adverse health ef fects and the WHO health-

related guidel ine value for chlorine is set at 5mg/l.

There is not a numerical standard for residual chlor ine in dr inking water

in Wales, however, water companies are required to measure residual

chlorine whenever they are collect ing samples for microbiological analysis

and any abnormal change in chlor ine concentrat ion must be investigated.

In addit ion, water companies are expected to have regard to consumer

acceptabi l i ty by investigating chlorine-related taste and odour complaints

f rom consumers. The Inspectorate has set a screening value of 2 mg/l for

the purpose of assessing the effect iveness of residual chlorine

management by water companies.

In 2011, across Wales, a level of residual chlor ine exceeding 2mg/l was

recorded on 16 occasions at four sites: Abermorddu service reservoir

(1 DVW), Penycae service reservoir (1 DVW), Alwen works (8 DWR) and

Bryn Berr iew service reservoir (6 SVT).

Dŵr Cymru Welsh Water (DWR) recorded residual chlorine values above

2mg/l on eight occasions at Alwen works (between September and

November). These were al l associated with a change over f rom chloramine

to f ree chlorine disinfect ion and an upgrade of the dis infect ion control

arrangements at Alwen Works (see the Coliform bacter ia at works sect ion).

The company received 11 associated chlorine-related complaints f rom


31

consumers between September and November 2011. As a consequence

of the improvements in contro l at Alwen works, the level of f ree residual

chlorine in water leaving Alwen works has been stabi l ised at a lower level

and this should be more acceptable to consumers.

Residual chlorine at a level greater than 2mg/l was recorded in 2011 on

six occasions at Bryn Berriew service reservoir operated by Severn Trent

Water. This small reservoir serves just seven propert ies and as a

consequence demand is highly variable affect ing chlorine control. The

Inspectorate wil l be monitor ing the effect iveness of the mea sures taken

by the company to maintain a more stable and acceptable level of free

residual chlor ine level at this site.

Disinfection by-products

To ensure the microbiological safety of publ ic water suppl ies , water

companies are required to dis infect wa ter at the treatment works before

supplying it through the distr ibut ion system to consumers. Disinfect ion may

be achieved by any appropr iate physical or chemical method, or a

combination of the two. The choice of method wil l depend on a range of

site-specif ic factors, but an important considerat ion is the requirement to

keep disinfect ion by-products (DBPs) to a minimum. This 1998 EU Drinking

Water Direct ive requirement was introduced for mally into nat ional law in

January 2010.

Chemical disinfectants are powerful oxidants that react with organic and

inorganic matter in raw water to form other compounds known as DBPs.

There are many dif ferent DBPs and the l ikelihood of any part icular ones

occurring in a given water supply can be predicted f rom the raw water

quality and the method of disinfect ion. A summary of commonly

encountered DBPs can be found in the World Health Organisation’s

Guidel ines for Drinking Water Quality 2004 Sect ion 8.5.4. Based on

current global research it is felt that two groups of compound s,

tr ihalomethanes (THMs) and haloaceticacids (HAAs) , serve as adequate

indicators for monitoring DBP performance overal l. The most appropr iate

means of control l ing DBPs is to remove the organic precursors f rom the

raw water before it is dis infected.

The Inspectorate has made a preliminary assessment of how well

companies in Wales are meeting the DBP rule using water company THM

data reported for 2011. For this init ia l evaluation, the Inspectorate has set

a screening criter ion of an annual average value of <5 0µg/l (50% of the

THM standard) as a broad indicator that general ly a company is minimising

DBPs effect ively. Table 16 shows that 10 zones in Wales exceeded this

screening criter ion (1 DVW, 2 SVT, 7 DWR). The Inspectorate expects

companies to review the r isk assessment for each of these suppl ies with

specif ic reference to compliance with Regulat ion 26 (as amended in 2010).


32

Where the need for addit ional control measures are identif ied then

companies should submit a Regulat ion 28 report to the Inspectorate, w ith

proposals for an act ion plan for any necessary steps to be taken.

Table 16: Numbers and names of zones exceeding an annual average

for trihalomethanes of >50µg/l

Company Number of zones

operated by company

Number of zones exhibit ing an

annual average for

trihalomethanes >50µg/ l

Name of zones exhibit ing an

annual average for

trihalomethanes >50µg/ l

Albion W ater 1 0 -

Dee Val ley W ater 18 1 Old W arren

Dŵr Cymru W elsh Water

84 7

Denbigh Blaenau Ffest in iog Holywel l /Mold L leyn Nor th Anglesey East Anglesey Penar th/Barry

Severn Trent W ater 209 2 W il lenhal l Nor th Nuneaton

Industry tota l 1,670 37 -

Note: Figures are for a l l zones operated by each company .

Fluoride

Traces of f luoride occur naturally in many water sources, part icularly in

groundwater. Consumers can obtain specif ic information on the level of

f luoride in the drinking water supply to their home or workplace f rom their

water company.

Fluoride is not removed by conventional water treatment. Some companies

f luoridate water suppl ies when required to do so by the local public health

author ity as a protect ion against tooth decay. There are no f luoridation

schemes in Wales; all 632 tests for f luoride taken across Wales met the

regulatory standard (1.5mg/l). Please refer to the DWI website

(www.dwi.gov.uk) for more information on f luoridat ion.

On 11 February 2011, a judicial review brought against South Central

Strategic Health Authority (SCSHA) by Geraldine Milner was concluded.

The review was about whether the SCSHA followed the correct procedure

when deciding to f luoridate publ ic supplies in the Southampton and South

West Hampshire area of England. The judge found in favour of the SCSHA

and the technical feasibi l i ty of the proposed f luoridation arrangements is

being assessed. No f luor idation schemes were proposed in Wales in 2011.


33

Nitrate and nitrite

Nitrate occurs natural ly in all source waters due to the decay of vegetable

material in soil. Nitrogenous fert i l isers used on arable farmland are a

signif icant source of nitrate in groundwater. Rainfall washes nitrate f rom

the soi l into lakes, r ivers and streams. Nitrate levels can be reduced by

water treatment or by blending with another, low nitrate w ater source.

Nitr ite may be formed when chloramine is used as the residual dis infectant

to maintain the microbiological qual ity in the distr ibut ion network. The

formation of nitr ite is control led by careful opt imisation of the

chloramination process. Chloramine is used in a number of suppl ies

in Wales. Nitr ite can also form in samples of water, af ter collect ion and

before analysis, especial ly if the sample is not kept cool. In Wales,

in 2011, two (DWR) out of a total of 986 tests exceeded the standard

of 0.5mg/l.

In June, one failure occurred at a consumer’s tap in the Llechryd zone,

Cardigan. Two similar failures were recorded in this zone in August 2010.

Previously two Dŵr Cymru Welsh Water works (Llechryd and Strata

Flor ida) were used to supply this zone and the company pract iced

seasonal chloramination at both. In 2011, only Llechryd works was used

without chloraminat ion. The Inspectorate notes that the changed operating

regime was insuf f icient to secure compliance with the nitr ite standard. I t is

disappoint ing to note this evidence that the water safety plan approach to

r isk assessment and r isk management is not yet fully embedded in Dŵr

Cymru Welsh Water’s operat ional arrangements.

In December, an elevated level of nitr ite occurred at a customer’s t ap

in a public building in the Strata Flor ida zone. The publ ic bui lding was

located at the end of a water main – a low f low situation is known to

enable the formation of nitr ite f rom chloramine. The company carr ied out

an invest igation and this led to a t emporary change to f ree residual

chlorine for a month. When making a change in residual dis infectant

arrangements (concentrat ion or type), companies should put in place

proactive operational monitoring for all relevant and associated standards

(col iforms, tr ihalomethanes, nitr ite and ammonia). The r isk of nitr ite

failures at this publ ic bui lding and in this zone did not change the

company’s overall of r isk. The Inspectorate commissioned a review of the

methodology of company r isk assessments in 2011.

Pesticides and related products

This group of substances, generically cal led pesticides, includes many

organic chemicals ranging from weed kil lers, to insectic ides and

fungicides. Water sources may contain traces of pestic ide residues as a

result of agricultura l use (pest control on crops) and non-agricultural use


34

(herbicides for weed control on highways , railways etc.). Water companies

are required to assess the r isk to drinking water supplies of pestic ide use

in source water catchments and then test for those that might be present.

Companies have documented potential and actual pest ic ide hazards

through their r isk assessments as informed by raw water monitoring . When

pestic ides are f irst detected, water companies wi l l enhance the monitoring

of raw water and not ify the Environment Agency to facil i tate appropr iate

act ion in the catchment to safeguard drinking water quality.

In 2011, as in 2010, the Inspectorate is pleased to note that none of the

tests in Wales exceeded the standard for total pestic ides. Likewise there

was 100% compliance (2,548 tests) for the four pesticides with a s tandard

of 0.03μg/l. Out of a total of 23,408 tests for individual pesticides none

exceeded the standard of 0.1μg/l .

pH (Hydrogen ion)

The acidity of water is measured by pH. The standard for pH requires it to

be above 6.5 and below 9.5. The most f requen t problems arise in upland

areas where water may pick up iron and humic and fulvic acids from peaty

soi l, result ing in acidic raw water ( low pH), which is commonly described

as ‘sof t water’. Such water has an increased potential to corrode iron

pipes. Where pH values above 9.5 occur this is usual ly due to leaching

f rom cement mortar- l ined mains.

In 2011, across Wales, out of a total of 2,318 tests, there were four

instances of non-compliance when the pH standard was exceeded on four

occasions (2 DVW, 2 DWR).

Dee Val ley Water reported a consumer’s tap sample f rom Legacy zone

near Wrexham with a pH value of 6.42 in January. The invest igation traced

the cause to poor pH control at the Legacy works during a per iod of very

cold weather, which may have af fected the solubil i ty of l ime used to adjust

the pH of the water. The company made adjustments to improve the

control arrangements by instal l ing new onl ine monitors at the works. The

company has also reviewed its control philosophy dur ing severe weather

following a second successive cold winter.

Also, in the cold weather during January , Dee Val ley Water reported a pH

value in a consumer’s tap sample f rom Wrexham Zone of 6.45. This zone

has experienced low pH levels in 2009, 2010 and 2011. The company has

previously attr ibuted the pH control problems in this zone to inadequate

control of l ime dosing during cold weather at Llwyn Onn works. The

Inspectorate is cr it ical of the company’s apparent inaction in response to

a known recurr ing problem and, in 2012, required the company to provide

a plan of the remedial act ions to be taken in relat ion to the operation and


35

control of the works to prevent a recurrence. The Inspectorate wi l l be

closely monitoring progress with the plan during 2012.

Dŵr Cymru Welsh Water reported a pH of 9.51 in the Blaenau Ffest iniog

zone from a sample col lected at a property dur ing May. The company has

suspected that the character ist ics of the water in this area, part icular ly the

low f low condit ions in the area and the extended per iod of travel b etween

the works and the property (est imated to be 11 days), may be impact ing on

changes to the pH and react ing with local mains which were l ined with

asbestos cement. The company has since replaced a 2km length of

asbestos cement- l ined main between the service reservoir and distr ibut ion

system serving the property and there have been no further elevated

values recorded in the zone since. The company has also made a var iety

of improvements at i ts work to increase the stabil i ty of the pH of the water

and has opt imised its chemical dosing.

In July, Dŵr Cymru Welsh Water reported a pH of 6.09 in a concessionary

supply of raw water. In order to meet the pH standard the company placed

magnaspheres (magnesium carbonate) in the raw water supply to raise the

pH, but this was not consistent ly ef fect ive. T he company has since

introduced a tank and new pipework into the supply system and this work ,

completed dur ing March 2012, should provide suff icient contact t ime for

the effect ive functioning of the magnasphere treatment regime.

Radioactivity

Gross alpha/gross beta/total indicative dose

Radioactivity in raw water can originate f rom natural substances or f rom a

specif ic point emission. Water companies are required to screen for

radionucl ides that emit either alpha or beta part ic les. I f such screening

exceeds guide values (gross alpha 0.1Bq/l, gross beta 1.0Bq/l) then fuller

analysis for specif ic radionucl ides is carr ied out to determine the origin.

Total indicat ive dose (TID) is a measure of the effect ive dose of radiat ion

through consumpt ion of the water. The guide value is 0.1mSv/year.

In 2011, out of 1,748 tests across Wales, there were no results for either

gross alpha or gross beta above screening values.

Tritium

Monitor ing for tr it ium is necessary only where a source of tr it ium is present

within a catchment and it has not been establ ished through other

environmental survei l lance programmes and studies that the level of

tr it ium is wel l below its parametr ic indicator value of 100Bq/l.

Dee Val ley has establ ished, by r isk assessment , that monitor ing for tr i t ium

is not required. Testing for tr it ium was carr ied out by Albion Water (four


36

tests), Dŵr Cymru Welsh Water (562 tests), SSE Water (one test) and

Seven Trent Water (12 tests). Al l results were sat isfactory ver ifying the

r isk assessments carr ied out by the companies.


Customers expect their dr inking water to be clear and bright in appearance

and free f rom discernible taste or odour. In recognit ion of this the

regulat ions st ipulate national standards for colour, odour and taste.

Companies are required to investigate the cause of any adverse results.

In 2011, eight samples f rom a total of 1,882 tests exhibited a discernible

odour (2 DVW, 6 DWR), f ive of these also had a taste (2 DVW, 3 DWR).

Earthy/musty

These descr iptors relate to situat ions where object ionable tastes or odours

are caused by fungi, materials in contact wit h water or algae in raw water.

In 2011, three samples out of a total of 1,363 were recorded as having an

earthy or musty taste. In Apri l , Dŵr Cymru Welsh Water identi f ied a musty

taste and odour in a sample f rom a consumer’s tap in the East Anglesey

zone in North Wales. The company carr ied out a comprehensive

investigation, including checking the operation of the Cefni treatment

works and records of consumer water quality complaints. The company

also carr ied out a water f it t ings inspect ion and no def icienc ies were

identif ied. No evidence of a wider taste problem in the zone was found.

Also in Apr il, Dŵr Cymru Welsh Water reported a musty taste and odour

in a consumer’s tap sample collected f rom the Abergavenny/Cwmti l lery

zone in Mid Wales. The company checked the operat ion of Talybont works

as this had previously been identif ied in the company’s r isk assessment

process as exhibit ing a taste and odour r isk f rom compounds found in the

raw water. As part of a legal ly binding programme of work , dif fused air

f lotat ion (DAF) has been installed to remove organic matter and improve

taste and odour in the supp ly to this zone.

Maintaining water quality in distribution

Elevated levels of iron or manganese are object ionable to consumers

because the water may appear turbid or discoloured due to unsightly

deposits and may also stain laundry and water f it t ings. Since 2004, the

Inspectorate has been monitor ing the progress of companies’ distr ibut ion

maintenance work using an index made up of three parameters (turbidity,

iron and manganese). Figure 17 shows the long-term improvements in

Wales. The trend over the past two years has been an improv ing one for

Dŵr Cymru Welsh Water in contrast to deteriorat ion in the Severn Trent


37

Water index. In 2011, there was also a sharp decl ine in the Dee Valley

Water index.

Figure 17: Percentage of tests meeting the standards for turbidity,

iron and manganese

99.40

99.50

99.60

99.70

99.80

99.90

100.00

2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Perc

enta

ge m

eeti

ng s

tand

ard

Wales

Dee Valley Water Dŵr Cymru Welsh Water Severn Trent Water

Note: A lb i on W ater have been supp l y ing water s inc e 2000 and have ach ieved 100% compl iance,

except in 2004, when they ach ieved 91.67%.

Discolourat ion of tap water of ten prompts consumers to contact their water

company. The number of people contact ing their water company about

discoloured water is reported annual ly to the Inspectorate in accordance

with Information Letter 1/2006. Looking at the trend since 2007, it can be

seen from Figure 18 that across the industry, the numbers of

discolourat ion contacts f rom consumers has fallen f rom nearly 84,000 to

below 54,000. The downward trend seen in Wales is in l ine with that

observed for the industry as a whole , with the f igure now standing at close

to 6,500 discolourat ion contacts, down by 30% since 2007. These

consumer contacts represent one-tenth of all consumer contacts to the

industry regarding discolourat ion.


38

Figure 18: Consumer contacts to companies for discolouration

2007–2011

0

10,000

20,000

30,000

40,000

50,000

60,000

70,000

80,000

90,000

2007 2008 2009 2010 2011

Wales

Rest of Industry

Looking more closely at the f igures for Wales, mapping of the rate of

consumer contacts by zone shows the changing picture f rom 2007 to 2011.

Rates of consumer contacts to companies about discoloured water in 2007

(Figure 19) i l lustrates the situation before del ivery of the AMP4

improvement work by companies. Figure 20 shows the comparable rate at

the end of 2011 af ter complet ion of the AMP4 investment.


39

Figure 19: Rate of consumer contact per 1,000 population reporting

black, brown or orange water in 2007


40

Figure 20: Rate of consumer contact per 1,000 population reporting

black, brown or orange water in 2011

When viewed together these two maps verify the improved consumer

exper ience across most of Wales during the f ive-year per iod (2007 –

2011). Areas exhibit ing a notable improvement with fewer discolourat ion

contacts are north of Bala and on the Lleyn peninsula in North Wales.

Key to the improved situat ion was investment in the period by Dŵr Cymru

Welsh Water to improve treatment performance , part icular ly in North Wales

at Alwen and Cwm Dulyn works. The longer-term programme

of strategic mains renovat ion accounts for the decrease in overal l numbers

of complaints across South and Mid Wales.

In contrast to this good picture , however, is the r ise in the number of

contacts about appearance in North East Wales around Wrexha m. This


41

area is served by Dee Valley Water and the company has entered into

a legal ly binding programme of work to clean the Wrexham ring main.

This receives water f rom Legacy and Llwyn Onn treatment works, where

treatment is inadequate in respect of manganese removal . This causes

deposit ion of manganese in the downstream mains. Both these works are

scheduled for improvement works, Llwyn Onn works (Figure 21) wi l l be

improved and the distr ibut ion system cleaned by the end of 2013 and

studies to determine the best solut ion at Legacy works wil l be completed in

the AMP5 period. Overal l , this investment wi l l benef it around 45,000

consumers.

Figure 21: New filters under construction February 2012 at Llwyn Onn

works (Dee Valley Water)

In the summer of 2011 there were f ive discoloured water incidents in

Wales, three occurring in July and two in August , affect ing consumers

in North Wales (Llyn Conwy, Gwynedd) and South West Wales (Bryngwyn

on the Gower peninsula and Haverford West, Pembrokeshire). Dŵr Cymru

Welsh Water has taken act ion to prevent these events recurr ing.

Across Wales in 2011, out of a total of 4,335 tests for iron and

manganese, there were ten failures for iron (9 DWR, 1 DVW) and six

failures for manganese (4 DWR, 2 DVW). Most of these failures were

isolated occurrences of disturbances of mains deposits c leared on

f lushing.


42

In February, Dŵr Cymru Welsh Water investigated an iron failure in a

consumer’s tap sample f rom a property in Newport , Gwent, South East

Wales. Follow-up samples f rom propert ies in the same cul-de-sac gave

satisfactory results , however, the company noted that there had been a

previous fai lure in 2010 from the locat ion. As a consequence, the area has

been surveyed to inform the company ’s Distr ibut ion Operation and

Maintenance Strategy (DOMS) and the need for either a regular f lushing

regime or mains renovation.

A sample col lected f rom a consumer’s tap in the Abergavenny/Cwmti l lery

zone, South East Wales, failed the standards for both iron and manganese

in December. There is a legal ly binding programme of work in place for

renovat ion of the distr ibut ion system in this area due for complet ion in

2013, therefore, as an inter im measure, Dŵr Cymru Welsh Water f lushed

the local mains to clear historic mains deposits.

Annex 4 detai ls the legally binding programmes of distr ibut ion

maintenance work scheduled to be completed between now and 2015 to

address ongoing distr ibut ion qual ity problems in Wales.

Maintaining water quality at the tap

Consumers expect their dr inking water to be clear and bright in

appearance and free from discernible taste , odour or contaminants.

Several parameters are not rout inely found in mains water , but instead

they gain access to tap water c lose to the point of use. For example ,

certain plumbing metals (ant imony, copper, lead and nickel) and sodium

introduced by water sof teners instal led in premises. Accordingly ,

remediat ion of failures for these parameters requires act ion to be taken

by property owners.

Table 22 i l lustrates the number of failures attr ibuted to condit ions within

premises across Wales. Overal l there were just six failures of the future

standard for lead >10µg/l (2 DVW, 4 DWR) .


43

Table 22: Failures in samples collected from taps where the cause was

attributed to the premises

Parameter Albion Water

Dee Val ley Water


Severn Trent Water

SSE Water

Metals

Ant imony 0–4 0–97 0–541 0–19 0–2

Copper 0–4 0–97 0–544 0–19 0–2

Lead >10 0–4 2–97 4–544 0–19 0–2

Nickel 0–4 0–97 0–542 0–19 0–2

Colour 0–4 0–224 0–1,325 0–49 0–2

Conduct ivi ty 0–4 0–298 0–1,720 0–31 0–7

Odour 0–5 0–229 0–1,615 0–31 0–2

pH 0–4 0–225 0–2,022 0–61 0–6

Sodium 0–4 0–97 0–542 0–19 0–2

Taste 0–4 0–227 0–1,363 0–31 0–2

Total 0–41 2–1,688 4–10,758 0–298 0–29

Note: Fa i lu res counted i n th is tab le are those caused by co nd i t ions or ar rangements in the prem ises .

In al l such cases the company must advise consumers of the fai lure and its

cause with information about the act ions needed to safeguard health in the

short term, as wel l as what is needed to effect a remedy in the longer

term. If the failure occurs in a publ ic bui lding, the company must go further

and, either alone, or act ing in col laborat ion with the local authority,

enforce act ion by the re levant persons.

Table 23 shows the number of invest igations in publ ic bu i ldings

consequent on a failure of a standard or exceedance of an indicator

parameter value. In 2011, there were two invest igations in publ ic bui ldings

in Wales and the circumstances are discussed below.


44

Table 23: Investigations in public buildings where action is required

by building owners

Company Total tests at

consumers’ taps Total tests at

publ ic buildings Investigat ions in publ ic buildings

Albion W ater 601 0 0

Dee Val ley Water

8,361 0 0


93,374 3,580 1

Severn Trent Water

5,071 0 0

SSE W ater 339 0 0

Total 107,746 3,580 1

Lead

The most common source of lead in tap water is pipework instal led before

the 1970s or the use of non-approved solder on cold water systems. Lead

may also leach f rom brass f it t ings. The standard of 10µg/l comes into force

at the end of 2013, but the Inspectorate has strongly recommended that

companies take act ion ahead of the new standard coming into force

(Guidance on the Implementation of the Water Supply (Water Quality)

Regulat ions 2000 – Regulat ion 30).

In 2011, companies in Wales identif ied six failures of the future standard

of 10µg/l out of a total of 666 tests. As i l lustrated in Figure 24, the

situat ion regarding compliance with the future standard for lead in Wales is

now the same as for the industry overal l .


45

Figure 24: Percentage of tests meeting the future standard of 10µg/l

for lead between 2002 and 2011

93

94

95

96

97

98

99

100

2002 2003 2004 2005 2006 2007 2008 2009 2010 2011

Perc

en

tag

e m

eeting

sta

ndar

d

10ug/l Industry 10ug/l Regional

Four out of the six zones where samples above 10µg/l of lead were

recorded are already subject to phosphate dosing which resu lts in a

protect ive layer inside pipework minimising the release of lead into tap

water.

Lead above 10µg/l was found in one sample f rom a publ ic bui lding in

Wales. Dŵr Cymru Welsh Water erroneously f lagged a contract ing f irm’s

premises as a publ ic bui lding in their data return to the Inspectorate. They

inspected the premises and found that the pipework had been jointed with

lead solder. The contract ing f irm were advised to use a solder appropr iate

for potable usage by the company.

In 2011, the Inspectorate commissioned research with the water industry

research organisat ion (UKWIR) to look beyond the current water treatment

measures now in place to reduce exposure to lead f rom tap water. The

study considered a wide range of quantitat ive and qual itat ive data ,

including the est imated number of propert ies with lead pipes in the UK,

lead in tap water measurements, and the costs and benef its of measures

such as water treatment and replacement of supply pipe s and service

pipes. One output of the project was an economic tool that enables users

to est imate the costs and benef its of basel ine phosphate dosing alongside

the alternatives of lead pipe replacement or rehabi l itat ion. W ider impacts

were also considered, including potential consequent ial wastewater

treatment costs, carbon emissions and other health benef its such as

reductions in copper concentrat ions in tap water.


46

The publ ished UKWIR report , Alternat ives to phosphate for

plumbosolvency control (12/DW/04/12), concluded there is no pract ical

alternative water treatment measure to the phosphate dosing regime

already in place and this was conf irmed as being effect ive in reducing lead

concentrat ions in tap water very substant ial ly. The report also makes clear

how replacement of a water company supply pipe wi l l not result in a

signif icant reduct ion in r isk of exposure to lead unless the customer

service pipe is also replaced at the same t ime. The research has identif ied

addit ional benef its attr ibutable to phosphate dosing in the form of reduced

amounts of copper leach ing f rom plumbing and a similar ef fect in relat ion

to iron concentrat ions. Pipe rel ining as an alternative to lead pipe

replacement is also discussed in the UKWIR report. Early test ing of this

approach did not result in rel ining being widely appl ied by the industry,

however, a new rel ining method has been developed which is potent ially

more cost benef icial and this is current ly undergoing tr ials. The f indings of

this research wi l l be taken into account in water company strategies for

minimising exposure to lead in the long term.

Drinking water quality events

Water quality events are classif ied into f ive broad categories based on the

init ial company report. The categories are:

Not significant: no further information required by an inspector to assess

the event.

Minor: i t is unl ikely that further information would be required by an

inspector to assess the event .

Significant: a ful l company report is usual ly required to enable an

inspector to assess the event .

Serious: in addit ion to a full company report, the assessment may involve

more than one inspector in the investigat ion.

Major: in addit ion to a full company report, wil l require an investigation led

by senior inspectors involving extensive information gathering and usual ly

site vis its.

In 2011, companies in Wales notif ied the Inspectorate of 25 events. Table

25 shows how these events were classif ied .


47

Table 25: Water quality events in Wales in 2011

Nature of event Risk assessment category (DWI)

Minor/not-signif icant

Signif icant Major/serious

2010 2011 2010 2011 2010 2011

Air in water - - - - - -

Chemical - 1 - - - -

Discoloured water 3 4 6 1 - -

Inadequate t reatment 1 - 5 - 1 -

Loss of suppl ies/poor pressure 1 1 3 - - -

Microbiological 4 2 2 4 - -

Taste/Odour 2 5 1 - - -

Health concern - 1 2 - - -

Publ ic concern 4 4 1 2 - -

Other - - 1 - - -

Wales overall 15 18 21 7 1 -

England and Wales 222 251 160 135 9 2

A summary of the nature, cause and durat ion of each event categorised as

signif icant, serious or major , along with detai ls of the Inspectorate

f indings, are set out in Annex 3 . Most events were of relat ively short

durat ion and the company took appropriate act ion to inform and safeguard

consumers and other stakeholders. A comparison of 2011 events with

those of 2010 shows a decrease in the numbers classif ied as signif icant,

serious and major (7 compared to 22 in 2010) . W ider learning points f rom

event invest igations during 2010 are highlighted by the following cases:

Detection of E.coli in treated water reservoir

In June, E.col i was detected in a sample taken from Boughton works in

Chester operated by Dee Val ley Water. The works abstracts water f rom the

River Dee and treatment is by dissolved air f lotat ion (DAF) , rapid gravity

f i l t rat ion (RGF) and granular act ivated carbon (GAC). Treate d water then

passes into a series of reservoirs and a water tower before entering the

distr ibut ion system. Al l invest igational samples were sat isfactory except

for one taken from Boughton water tower. A similar event had occurred in

2005 when Dee Val ley Water failed to identify the cause. A subsequent

audit in 2006 by the Inspectorate raised concern s about the water tower

and a recommendat ion was made to review the arrangements. In January ,

the company used a remotely operated vehicle (ROV) to inspect the

circular reservoir and the water tower as part of ongoing company

investigations of this works. This conf irmed its poor condit ion. In the 2006

audit , the Inspectorate had noted the company’s pract ice of dosing the

tower with sodium hypochlor ite and advised this would negate the purpose

of microbiological test ing at service reservoirs ( indicators of integrity).

When assessing the 2011 event it was evident the company had cont inued

with the pract ice ( ignoring the advice given) to the detr iment of water

quality. Disappoint ingly, the company had failed to take the tower out of


48

service to enable repairs and also disregarded its own procedures for

managing water turnover in these structures. Addit ional ly , alarms that

respond to a deter iorat ion in treated water qual ity were not acted on in

a t imely manner. In l ight of all the information available, including the

company’s r isk assessment, the Inspectorate concluded that the control

measures were no longer suff icient and carr ied out a further audit in

October (see the Technical audit act iv ity sect ion) whereupon further

def iciencies were found at the works (f i l ter management and the l ime

plant). The tower was taken out of supply and enforcement act ion was

taken. A Notice was put in place in March 2012 sett ing out short -, medium-

and long-term measures with agreed t imescales to protect publ ic health.

The Inspectorate is very cr it ical of the company for relying on a short -term

measure (manual dosing of chlorine) for years and not carrying out

medium-term measures ( inspect ion) and long-term measures (remediat ion

of integrity defects). This event i l lustrates why those companies who dose

chlorine into reservoirs to mask evidence of integrity problems are i l l

advised to do so. This event also highl ights the need for Directors to

always satisfy themselves personal ly that advice given by the Inspectorate

is not disregarded.

E.coli failures at a concessionary supply

In May, a rout ine sample f rom a concessionary supply near Swansea

contained E.col i and col iform bacteria. This supply of raw water from the

Upper Ll iw reservoir is treated with a point of use treatment device

(ultraviolet treatment and act ivated carbon). There had been previous

sample failures at this property. On investigation , Dŵr Cymru Welsh Water

was able to determine that the treatment unit was functioning correct ly and

the cause of the failure was the unit having been turned off by the

consumer. The consumer was given advice about the need for treatment to

be cont inuous. The company has made improvements to the point of use

device so that its functional ity is visible to the user. Notices are in place

for all the propert ies supplied by means of a concessionary raw water

supply f rom Upper Ll iw reservoir. The long -term risk mit igat ion is for the

propert ies to be connected to the publ ic mains supply (by March 2015).

In l ight of this event , the company has brought forward the t imetable for

these works, which should be completed within two years. Companies are

reminded of the need to engage effect ively with consumers served by

concessionary suppl ies to gain their full co-operat ion with both the short-

and long-term control measures. This event reinforces the unsatisfactory

nature of concessionary supply arrangements generally and the

Inspectorate expects companies to pr ior it ise permanent solut ions.


49

Samples contaminated within the laboratory

In June, a batch of compliance samples col lected by Dŵr Cymru Welsh

Water were reported as having a higher than expected number of samples

posit ive for coliform bacteria, which prompted the laboratory to investigate

further. The company col lected follow-up samples and met with the

laboratory on the same day to init iate a joint investigation. The follow-up

samples processed in a dif ferent laboratory gave satisfactory results.

Repeat analysis of the original posit ive samples also gave satisfactory

results (col iforms not detected). The cause of the posit ive samples was

traced to aer ial contaminat ion in the laboratory. A compressed air lance

had been used to clean the laboratory environment (and air condit ioning

ducts) causing dispersal of microbes into the atmosphere immediately prior

to analysis of the original samples commencing. The laboratory area

subsequently underwent an intensive clean to remove any residual

contamination and changes were made to working pract ices to prevent a

recurrence. The Inspectorate welcomed the company’s prompt

investigation, part icular ly the vis it to the laboratory. This event highl ights

the r isks associated with poor analyt ical pract ice and the need fo r

companies to be aler t to this as a cause of any unusual pattern of sample

results.

No of fences are currently under considerat ion by the Inspectorate in

connection with any of the events that occurred in Wales in 2011.

Technical audit activity

The Inspectorate has operated a r isk -based approach to technical audit

since 2005 and no technical audit takes place without a reason.

On 14 December 2011, and in l ine with the Government ’s Better

Regulat ion policy, Parl iament gave the Chief Inspector powers in t he

Publ ic Bodies Bil l to recover the costs of its regulatory act ivit ies f rom the

industry f rom January 2013 onwards. Dur ing 2012, the Inspectorate has

consulted the industry and other stakeholders on the proposed charging

regime, the detail of which wi l l be set out in Orders laid under the Bi l l in

autumn 2012. Whereas the work of inspectors in assessing companies’

compliance with the drinking water monitoring requirements as set out in

the drinking water regulat ions can be predetermined, the technical audit

act ivit ies of inspectors is less predictable , however, the nature and volume

of technical audit act ivity over the past seven years is i l lustrated in Figure

26 as an indication of the scope and extent of the new charging

arrangements going forward.


50

Figure 26: Technical audit activit ies in Wales 2005–2011

0

5

10

15

20

25

30

35

40

45

50

2005 2006 2007 2008 2009 2010 2011

Nu

mb

er

of

au

dit

s

Abstraction and treatment

Service reservoir integrity and management

Distribution operational maintenance

Sampling and analysis

Response to recommendations

Compliance with requirements for Legal Instruments

Other

Consumer complaint handling

Table 27 sets out all the r isk -based technical audits, which took place in

Wales during 2011 together with summary f indings. This is fol lowed by

information about industry-wide themes assessed dur ing the year and the

part iculars of consumer complaint investigations by inspectors , including

a case study.

Table 27: Summary of the technical audit findings in Wales in 2011

Company Location and reason

Main f indings from audit

Audit focus: Abstract ion and treatment

Dee Val ley Water

L lwyn Onn works – turb id i ty and pH

Unsat isfac tory.

A Not ice has been put in p lace in re lat ion to required improvements to mit igate the fol lowing ident i f ied r isks:

Condi t ion of l ime dos ing plant .

Condi t ion of f ina l water reservoi rs.

No treatment for manganese and insuf f ic ient treatment for Cryptospor id ium .


51



Dee Val ley Water

Boughton works – event and microbiol ig ical fai lures

Unsat isfac tory.

Noted poor dis tr ibut ion of air scour on granular act ivated carbon f i l ters.

Issues wi th the l ime plant, mature trees adjacent to treated water reservoirs and general lack of maintenance.

Enforcement act ion taken. Not ice issued in re lat ion to the tower that was in a s tate of d isrepair wi th holes in the roof , the roof covered in b ird guano and inadequate roof dra inage. Holes the s ize of pigeons in the internal tank.

Audit focus: Distr ibution operat ional maintenance


Depot and contractor – water supply hygiene

General ly sat isfac tory.

Depot , some vegetat ion growth around the stored p ipes.

Hole in the ground: one contractor not carrying an up-to-date hygiene card, No water avai lable for hand washing s inks (a l though wipes were avai lable), d iesel cans in the vans not bunded, Instachlor tablets for chlor inat ion in vans had no expiry date.

Dee Val ley Water

Meter f i t t ing and depot – water supply hygiene

Unsat isfac tory.

Fuel can in van secured, but not contained/bunded.

Supervisor had to prompt re -d is infect ion of p ipe end af ter cut ends were ‘ f i led ’ wi th angle gr inder.

Ends d ipped in bucket of d ir ty chlorous, no d is infect ion of internal surfaces of new sect ion, due to l im its of d is infect ion method (see below) .

Method issues.

Dis infect ion of ends/f i t t ings carr ied out wi th a paint brush f rom an open conta iner of ch lorous throughout the job such that chlorous becomes increas ingly d i r ty and therefore less ef fect ive.

Solut ion is made up week ly f rom 10% stock l iqu id solut ion, ( i .e . not tablets) – not best pract ice.

Weekly solut ion carr ied on van has no date of expiry, though of f ice paper records are kept .

Procedures prescr ibe the need for operators to car ry out water qual i t y hygiene checks for a l l network jobs, but th is is not documented and therefore the procedures are not amenable to audit .

No f lushing guidance other than to ‘run unt i l c lear . ’ Need for a more measured approach.


52



Dee Val ley Water

Meter f i t t ing and depot – water supply hygiene (cont inued)

Qual i t y of storage ar rangements incons istent (need a d isc ipl ined approach to mainta in ing a common s tandard) – p ipes a l l of f the ground, but many uncapped ends observed, method of capping var ied, some caps in poor state of repair ( fa l len apart, in some cases) or poor ly f i t ted. Some ends covered in b lack b in bags in very poor state of repair f rom wind damage, poss ib ly animal damage, some covered in robust p las t ic.

Some f i t t ings stored outs ide the secure compound – of f ground, some covered some not, some in tota l ly unsuitable condi t ions by per imeter fence against external vegetat ion.

No apparent procedure for control of reuse of o ld stock.

No vermin contro l – ment ion of occasional mouse and rabbits on s i te.

Audit focus: Sampling and analysis


Samplers, nor th east Wales


Aerat ion at f ina l taps at Bretton works on pump s tart -up; fol lowed procedure correct ly and d iscarded sample , but procedure ra ises quest ions about whether the aerat ion ref lects the supply f rom si te and how th is might be repor ted for invest igat ion .

Inadequate sampl ing fac i l i t ies at service reservoir s i tes . Recommended pr ior i t is ing faci l i t ies upgrades .


Samplers, south east Wales


Good procedures in p lace for tra in ing and development of samplers and regular monthly toolbox ta lks.

Cr i t ica l of sampl ing faci l i t ies at service reservoirs .

Suggested samplers are reminded to check their vans for out of date mater ial .

Audit focus: consumer complaint handling


Discolourat ion (1)

Other (2)

Al l sat isfac tory.

Audit focus: Compliance with requirements for Legal Instruments

Dee Val ley Water

Wrexham r ing main – manganese undertak ing

Content of under tak ing negot iated and Legal Ins trument now in place.

During 2011, the Inspectorate audited the water supply hygiene

procedures of 11 companies across the industry following receipt

of information which inc reased the Inspectorate’s overall assessment of

r isk associated with the way companies carry out work on the network.


53

These audits covered equipment storage condit ions in depots and vans, as

well as mains repairs and meter installat ions. The outcome of most audits

were general ly sat isfactory, but examples of poor pract ice were identif ied

where contaminat ion of drinking water might have, or did, occur as a

consequence of unsuitable storage of f it t ings, pipes and other materials,

insuff icient c learance of soi l f rom around open pipes or connections,

inadequate f lushing or dis infect ion or a lack of good hygiene within vans.

The f indings were summarised and publ ished in an Information Letter

( IL 04/2012) to promote industry-wide learning and improvement in this

crit ical ly important aspect of day-to-day operat ions.

Figure 28: An example of unsuitable storage of pipes prior to

installation

Complaints to the Inspectorate

The number of Welsh consumers who had cause to complain to the

Inspectorate because the water company had failed to resolve a water

quality concern increased in 2011 to three compared to just one in 2010.

Consumers also contact water companies when they are dissatisf ied with

their water qual ity and complaints regarding appearance, taste and odou r,

and incidence of i l lness have decreased from 10,357 in 2010 to 9,617 in

2011.


54

Table 29 shows the number of complaints about water qual ity received by

the Inspectorate in 2011 alongside the annual rate of consumer contacts to

water companies about water quality issues. General ly , complaints made

direct ly to the Inspectorate arise when a company’s handling of a

consumer contact has fallen short of best pract ice and this only comes to

l ight as a result of intervention by an inspector. For this reason, ther e is

no direct relat ionship between the f igures set out in Table 29 and it is not

uncommon for complaints to the Inspectorate to be f rom customers of

companies exhibit ing a low rate of consumer contact generally.

Table 29: Complaint rates to industry and to the Inspectorate

Company Rate of consumer contacts per 1,000 people

1 to water

companies in 2011

Number of complaints to the Inspectorate in 2011

Albion W ater - -

Dee Val ley Water

4.8 -


3.0 3

Severn Trent Water

1.5 -

SSE W ater 0.4 -

Industry rate 1.9 34

1Rate o f contac ts for appearance, tas te and odour , and i l l ness

The following complaint case example f rom 2011 i l lustrates why the

Inspectorate considers it important that companies have in place ef fect ive

arrangements for diagnosing consumer contacts.

Case example

During August , a consumer in the Fl int area contacted the Inspectorate

about an intermittent problem with brown coloured tap water. She reported

that neighbours were experiencing similar problems and , whi le the problem

was intermittent , it had been occurr ing for a number of months. D ŵr Cymru

Welsh Water had investigated the situat ion and, af ter ruling out network

act ivit ies by them, had begun to check for i l legal use of hydrants as a

possible cause of periodic mobil isat ion of histor ic mains deposits caused

by uncontrol led changes in f low and pressure. The company had vis ited

the consumer at the outset to give reassurance about general water

quality, however, the consumer remained concerned and refused to use

the supply. The company had not taken adequate water samples at that

t ime and therefore did not have contemporaneous evidence of safety to


55

give to the consumer. Subsequent ly the consumer observed a street

cleaner using a hydrant to draw water and reported this to the company.

The company was unable to apprehend the third party , but was able to

take act ion in the area to carry out a controlled f lush to remove deposits

f rom the mains and prevent further episodes of discolourat ion occurring.

Companies are reminded of the importance of water quality contacts,

which may be the f irst, or only, s ign of a signif icant problem. I t is essent ial

that companies act promptly on information point ing towards i l legal use of

hydrants, recognising the potential for consumers to assist with such

investigations. There should be regular audits of l icenced users of

hydrants to ensure that procedures for maintaining water qual ity are

complied with and that the locations selected for withdrawing water are

appropr iate and unl ikely to impact on the quality of water received by

consumers in the local ity .

For further information on the Water Supply (Water Qual ity) Regulat ions

2010 Regulat ions (Wales) , or the microbiological and chemical parameters

covered by the regulat ions please refer to the DWI website

(www.dwi.gov.uk) .

I f you have a need for more specif ic in formation than that on our website,

please contact us on the DWI enquiry l ine: 0300 068 6400.


56

Annex 1 Further sources of information

The publ icat ion Drinking water 2011 comprises the regional reports for

England and a report covering Wales. There are four regional reports for

England (Central and Eastern, London and South East, Northern, and

Western) and one for Wales ( in two languages). Each report presents

information f rom 2011 under the following headings:

Overview of drinking water qual ity in the region.

Water supply arrangements.

Drinking water qual ity test ing.

Drinking water qual ity results.

Technical audit act iv ity.

Drinking water qual ity events.

There are also separate reports covering private water supplies, one

cover ing England and one covering Wales.

The reports and other content are publ ished on the DWI website

(www.dwi.gov.uk).

Content of the CD

The CD suppl ied with the printed report holds all of the above content and

addit ional ly it contains:

Water company look-up tables

These summarise al l the results of water company monitor ing in 2011.

They provide information on:

what was tested;

how many tests were performed;

the range of the results of test ing; and

how many tests failed to meet the standards.

Significant drinking water qual ity events in England and

Wales 2011

To promote shared learning, the Inspectorate has compiled a l ist of al l

events that occurred in 2011 which i l lustrate the nature and cause of each

event, the main act ions by the company and f indings f rom the inspectors ’

assessments. Relevant content f rom this overal l l ist is contained in an

annex to each regional report.


57

Annex 2 Glossary and description of standards

These def init ions wil l assist the understanding of the report where

technical terms have been used.

µg/l microgram per l i t re (one mil l ionth of a gram per l i t re) .

1,2-Dichloroethane is a solvent that may be found in groundwater in the v ic in ity of industr ia l s i tes . W here necessary i t can be removed by spec ia l water treatment . A European health-based standard of 3μg/ l appl ies.

Acrylamide European heal th-based s tandard. A monomer is not normal ly found in dr ink ing water. I t is produced in the manufacture of polyacrylamides occas ional ly used in water treatment . I ts presence in dr ink ing water is l im it ed by control of the product spec if icat ion. Standard is 0.1µg/ l .

Aesthetic assoc iated wi th the senses of taste, smel l and s ight .

Aggressive

a term used to indicate that the water has a tendency to d issolve copper (and other metals) f rom the inner surface of a p ipe or water f i t t ing such as a tap.

Alkali

a solut ion conta in ing an excess of f ree hydroxyl ions, wi th a pH greater than seven.

Aluminium occurs natura l ly in some source waters . I t is removed f rom dr ink ing water by convent ional water t reatment (coagulat ion and f i l t ra t ion) . Aluminium sulphate and polyaluminium chlor ide may be used as water treatment chemicals at some water treatment works. A nat ional standard of 200μg/ l appl ies.

Ammonium salts are natura l ly present in trace amounts in most waters. Their presence might indicate contaminat ion of sanitary s ignif icance and they interfere wi th the operat ion of the dis infect ion process. An indicator parameter wi th a guide value of 0.5mg/ l.


58

Analytical qual ity control (AQC)

the method used to ensure that laboratory analys is methods are performing correct ly.

Antimony is rare ly found in dr ink ing water . Trace amounts can be der ived f rom brass tap f i t t ings and solders. A European heal th -based standard of 5μg/ l appl ies.

Aquifer water -conta ining underground s trata.

Arsenic occurs natura l ly in only a few sources of groundwater. Spec if ic water t reatment is required to remove i t . A European health -based s tandard of 10μg/l appl ies .

Authorised departure author isat ion for a water company to temporar i ly supply water exceeding a dr ink ing water standard, granted by the author i t ies only when there is no r isk to human health.

Benzene is present in petro l. I t is not found in dr ink ing water , but i t can migrate thr ough underground p last ic water p ipes i f petro l is spi l t in the v ic in ity. A European health-based standard of 1μg/ l appl ies . Some bott led waters and sof t dr inks which inc lude sodium benzoate as an ingredient have been reported as conta ining benzene.

Benzo(a)pyrene is one of several compounds known as polycyc l ic aromat ic hydrocarbons (PAHs) . Their source in dr ink ing water is as a resul t of deter iorat ion of coal tar , which many years ago was used to l ine water pipes. Due to extens ive water mains refurb ishment and renewal i t is now rare to detect th is substance in dr ink ing water. A European health-based standard of 0.01μg/ l appl ies.

Boron in surface water sources comes f rom industr ia l d ischarges or f rom detergents in treated sewage ef f luents . The very low concentrat ions found in some dr ink ing waters are not a concern to publ ic heal th. A European heal th -based standard of 1mg/ l appl ies .

Bromate can be formed dur ing d is infect ion of dr ink ing water through a react ion between natura l ly occurr ing bromide and strong ox idants (usual ly ozone). I t may be generated in the manufacture of sodium hypochlor i te d is infectant . Except ional ly, groundwater be contaminated with bromate, re leased f rom industr ia l s i tes . A European health-based standard of 10μg/ l appl ies.


59

Bulk supply water suppl ied in bulk , usual ly in treated form, f rom one water company to another.

Cadmium is rare ly detected in dr ink ing water and trace amounts are usual ly due to d issolut ion of impur it ies f rom plumbing f i t t ings. A Europea n health-based s tandard of 5μg/ l appl ies .

Catchment

when used in connect ion wi th water , the catchment is the area dra ined by a r iver or water body.

Chloramination the process of generat ing a chloramine d is infectant res idual in water leaving a treatment works.

Chloramine a substance formed by a react ion between chlor ine and ammonia, used as a d is infectant in d istr ibut ion systems because of i ts long - las t ing propert ies compared to chlor ine.

Chloride is a component of common sal t . I t may occur in water natura l ly, but i t may also be present due to local use of de- ic ing salt or sal ine intrus ion. An indicator parameter with a guide value of 250mg/l .

Chlorine residual the small amount of ch lor ine or chloramines present in dr ink ing water to maintain i ts qual i t y as i t passes through the water company’s network of p ipes and household p lumbing.

Chromium is not present in dr ink ing water . A European health-based s tandard of 50μg/ l appl ies.

Clostridium perfringens is a spore-forming bacter ium that is present in the gut of warm-blooded animals . The spores can survive d is infect ion. The presence of spores in dr ink ing water indicates h is tor ic contaminat ion that requires invest igat ion. The standard is 0 per 100ml.

Coagulat ion a process employed dur ing dr ink ing water treatment to ass ist wi th the removal of par t icu late matter.

Coliform bacteria

are widely d istr ibuted in the environment of ten as a result of human or animal ac t ivi ty, but some grow on p lant mat ter . Their presence in a water supply indicates a need to invest igate the integr i ty of the water supply system. The s tandard is 0 per 100ml.


60

Colony counts are general techniques for detect ing a wide range of bacter ia, the types and numbers being dependent on the condit ions of the test . These counts , i f done regular ly, can help to inform water management, but they have no direct heal th s ignif icance. The s tandard is ‘no abnormal change’.

Colour occurs natura l ly in upland water sources. I t is removed by convent ional water treatment. A nat ional standard of 20mg/ l on the Plat inum/Cobalt (Pt /Co) scale appl ies .

Communicat ion pipe the connect ion f rom the water main to the consumer’s property boundary.

Compliance assessment a compar ison made by the Inspectorate of data gathered by water companies against standards and other regulatory requirements .

Compound a compound cons ists of two or more e lements in chemical combinat ion.

Concessionary supplies histor ica l f ree suppl ies of water for a householder , es tabl ished when a company wanted to lay mains across land and the landowner might agree, subject to a permiss ion, to take a supply of water f rom the main.

Conduct ivity is a non-spec if ic measure of the amount of natura l d issolved inorganic substances in source waters . An indicator parameter wi th a guide value of 2,500µS/cm.

Contact tank a tank, normal ly s i tuated on a treatment works s ite, which forms par t of the d is infect ion process. A d is infectant chemical (normal ly chlor ine) is dosed into the water as i t f lows into the tank. The per iod of t ime that the water takes to f low through the tank a l lows suf f ic ient ‘contact ’ t ime for the chemical to k i l l , or deact ivate, any v iruses or pathogenic organisms that may be present in the water.

Contravent ion a breach of a regulatory requirement.

Copper in dr ink ing water comes mostly f rom copper p ipes and f i t t ings in households. In general, water sources are not aggress ive towards copper, but problems very occasional ly occur on new hous ing estates. These ‘b lue water ’ events can be avoided by good p lumbing pract ices. A European health-based standard of 2mg/l appl ies .


61

Cryptosporidium is a paras ite that causes severe gastroenter i t is and can survive d is infect ion. In the UK, cont inuous monitor ing is under taken at works c lassif ied by the company as being at s ignif icant r isk .

Cyanide is not present in dr ink ing water . A European health-based s tandard of 50μg/ l appl ies.

Dead leg refers to a p iece of p ip ing which is stopped of f at one end, but is connected to the supply at the other end and can result in stagnant water in the p ipework.

Distribution systems a water company’s network of mains, p ipes, pumping stat ions and service reservoirs through which treated water is conveyed to consumers.

Drinking water standards the prescr ibed concentrat ions or values l is ted in regulat ions.

EC Drinking Water Direct ive Counci l Direct ive 98/83/EC December 1998 – set t ing out dr ink ing water standards to be appl ied in member states.

Enforcement act ion the means, as set out in the W ater Act 1989 and consol idated into the W ater Industry Act 1991, by which the Secretary of State requires a water company to comply w i th certa in regulatory requirements.

Enterococci see Escher ichia col i .

Environment Agency the Environment Agency is respons ib le for mainta in ing or improving the qual i t y of f resh, marine, surface and underground water in England and W ales.

Epichlorohydrin can be found in trace amounts in polyamine water t reatment chemicals. I ts presence in dr ink ing water is l im ited by contro l of the product spec if icat ion. A European heal th -based standard of 0.1μg/ l appl ies.

Epidemiology a process of s tudying the d istr ibut ion of cases of d isease wi thin a populat ion in re lat ion to exposure to poss ible sources of the infect ion, wi th a v iew to establ ish ing the actual source of the infect ion.


62

Escherichia col i and Enterococci

are bacter ia present in the gut of warm -blooded animals. They should not be present in dr ink ing water and, i f present , immediate act ion is required to ident i fy and remove any source of faecal contaminat ion that is found. The standard is 0 per 100ml.

Event

water companies have to inform the Inspectorate about occas ions when water qual i t y or suf f ic iency is af fected or when publ ic conf idence in dr ink ing water qual i ty may be impacted. The Inspectorate refer to these ins tances as ‘Events ’ .

Filt ration the separat ion of suspended par t icu late matter f rom a f lu id.

Fluoride occurs natura l ly in many water sources, espec ial ly groundwater. I t cannot be removed by convent ional water treatment so h igh levels must be reduced by b lending wi th another low f luor ide water source. Some water companies are required by the local heal th author i ty to f luor idate water supplies as a protect ion against tooth decay. The dr ink ing water standard ensures levels are safe in e ither c ircumstance. Fluor idat ion of water is a Depar tment of Health pol icy. A European health-based s tandard of 1.5mg/ l appl ies.

Geosmin a substance produced by the growth of a lgae, normal ly in surface waters which g ives r ise to a character is t ic ‘ear thy’ or ‘musty’ taste or odour.

Granular activated carbon an adsorbent f i l t ra t ion media used to remove trace organic compounds f rom water .

Gross alpha/gross beta

radioact iv i ty in raw water can or ig inate f rom natura l substances or f rom a spec if ic point emission. W ater companies are required to screen for radionuc l ides that emit e ither a lpha or beta par t ic les . I f such screening exceeds guide values (gross a lpha 0.1Bq/ l , gross beta 1.0Bq/ l) then fu l ler analys is for spec if ic radionuc l ides is carr ied out to determine the or igin.

Groundwater water f rom aquifers or other underground sources.

Hydrogen Ion

(pH)

gives an indicat ion of the degree of ac id i ty of the water . A pH of 7 is neutra l; va lues below 7 are ac id ic and values above 7 are a lkal ine. A low pH water may result in p ipe corros ion. This is corrected by adding an alkal i dur ing water t reatment. A specif icat ion of between 6.5 and 9.5 appl ies.


63

Improvement programmes water company improvement works, these are legal ly b inding on the company and each programme wi l l remedy an actual or pote nt ia l breach of a dr ink ing water s tandard wi th in a spec if ied t ime per iod.

Indicator organism an organism which indicates the presence of contaminat ion and hence the poss ib le presence of pathogens.

Indicator parameter something that is measured to check that control measures, such as water treatment , are work ing ef fect ive ly.

Information Letter formal guidance to water companies g iven by the Inspectorate and publ ished on the Inspectorate ’s webs ite at www.dwi.gov.uk

Inspectorate The Dr ink ing W ater Inspectorate.

Iron is present natura l ly in many water sources. I t is removed by water treatment. Some iron compounds are used as water treatment chemicals. However, the commonest source of iron in dr ink ing water is corros ion of iron water mains. A nat ional s tandard of 200μg/l appl ies .

Lead very occasional ly occurs natura l ly in raw waters, but the usual reason for i ts presence in dr ink ing water is p lumbing in o lder propert ies. I f the water supply has a tendency to d issolve lead then water companies treat the water to reduce consumer exposure. The permanent remedy is for householders to remove lead p ipes and f i t t ings. A European heal th -based standard of 25μg/ l appl ies, but 10μg/l wi l l apply f rom 25 December 2013 onwards.

m3/d cubic metre per day.

Manganese is present natura l ly in many sources and is usual ly removed dur ing treatment . A nat ional standard of 50μg/ l appl ies .

Mean zonal compliance percentage

a measure of compl iance wi th dr ink ing water standards introduced by the Inspectorate in 2004.

Mercury is not found in sources of dr ink ing water. A European health-based standard of 1μg/ l appl ies.


64

Methyl- isoborneol (MIB) a natura l substance produced by the growth of a lgae, normal ly in surface waters which g ives r ise to a character is t ic ‘eart hy’ or ‘musty’ tas te or odour. I t is detected by the method for assessing tas te and odour .

mg/l mil l igram per l i t re (one thousandth of a gram per l i t re) .

Microbiological assoc iated wi th the study of microbes.

Ml/d megal i tre per day (one Ml/d is equivalent to 1,000 m

3/d , or to 220,000 gal lons/d) .

Nickel occurs natura l ly in some groundwater and where necessary spec ia l treatment can be insta l led to remove i t . Another source of nickel in dr ink ing water is the coat ings on modern taps and other p lumbing f i t t ings. A European health -based standard of 20μg/ l appl ies .

Nitrate occurs natura l ly in a l l source waters a l though h igher concentrat ions tend to occur where fert i l isers are used on the land. Nitrate can be removed by ion exchange water treatment or through b lending wi th other low ni trate sources. A European health-based standard of 50mg/ l appl ies .

Nitrite is somet imes produced as a by-product when chloramine is used as the essent ia l residual d is infectant in a publ ic water supply. Chloramine is the res idual d is infectant of choice in large d is tr ibut ions systems because i t is more stable and long- last ing. Carefu l operat ion of the d is infect ion process ensures levels of ni tr i te are kept below the standard. A European health -based s tandard of 0.5mg/l appl ies.

Notice

an ins truct ion served by the Secretary of State ( in the case of water suppl ies , the Chief Inspector of W ater) requir ing spec if ic act ions to be taken by the rec ip ient wi th in a spec if ied t imescale.

Odour can ar ise as a consequence of natura l processes in surface waters, par t icular ly between late spr ing and ear ly autumn. W ater treatment with act ivated carbon or ozone wi l l remove natura l substances caus ing taste. The s tandard relates to the evaluat ions of a panel of people assessing samples in the laboratory.

Ofwat the water industry’s economic regulator .


65

Oocyst the res istant form in which Cryptospor id ium occurs in the environment, and which is capable of caus ing infect ion.

Organoleptic character is t ics of a substance as detected by ou r senses, for example taste, odour or colour.

Ozone process (ozonation) the appl icat ion of ozone gas in dr ink ing water t reatment.

Parameters the substances, organisms and propert ies l is ted in Schedule 2 and Regulat ion 3 of the regulat ions. Parameter def in it ions can be found in th is annex.

Pathogen an organism which can infect humans and cause d isease.

PCV see ‘Prescr ibed concentrat ion or value’ .

Periodic review the economic regulator ’s process of sett ing water pr ices.

Pest icides any fungic ide, herbic ide, insect ic ide or re lated product (excluding medic ines) used for the control of pests or d iseases.

Pest icides – organochlorine compounds (aldrin, dieldrin, heptachlor, heptachlor epoxide)

are no longer used in the UK because they are pers is tent in the environment. They are not found in dr ink ing water . A European chemical standard of 0.03μg/ l for each compound applies .

Pest icides – other than organochlorine compounds

is a d iverse and large group of organic compounds used as weed k i l lers, insect ic ides and fungic ides. Many water sources conta in traces of one or more pest ic ides as a resul t of both agr icu ltura l and non-agr icu l tura l uses, main ly on crops and for weed contro l on h ighways and in gardens. Where needed, water companies have insta l led water treatment (act ivated carbon and ozone) so that pest ic ides are not found in dr ink ing water . W ater companies must test for those pest ic ides used widely in their area of supply. Pest ic ide monitor ing thus var ies according to r isk . A European chemical standard of 0.1μg/l for each indiv idual substance and 0.5μg/ l for the tota l of a l l pest ic ides appl ies .

Phosphate dosing t reatment of water that resul ts in a protect ive f i lm bui ld ing up on the ins ide of p ipes minimising the l ike l ihood of lead being present in dr ink ing water suppl ied through lead p ipes.

Plumbosolvency the tendency for lead to d issolve in water.


66

Polycyclic aromatic hydrocarbons

(PAHs)

is a group name for several substances present in petroleum-based products such as coal tar . (see Benzo(a)pyrene l is ted above for more informat ion) . A European health -based standard of 0.1μg/l for the sum of a l l the substances appl ies.

Powdered activated carbon (PAC)

powdered act ivated carbon is employed in treatment processes to remove pol lu tants.

Pre- and post-renovation assessment (PPRA)

a programme of assessment before and af ter mains renovat ion to demonstrate jus t i f icat ion for the work , and the improvements achieved by the renovat ion.

Prescribed concentration or value (PCV)

the numerical va lue assigned to dr ink ing water standards def in ing the maximal or min imal legal concentrat ion or value of a parameter .

Private supplies water suppl ied for human consumption or food product ion which is not provided by a water undertaker or l icensed water suppl ier .

Protozoan parasites a s ingle cel l organism that can only survive by infect ing a host .

Public Register dr ink ing water qual i t y informat ion made avai lable to the publ ic by water companies as required by regulat ions.

Public suppl ies water suppl ied by a company l icensed for that purpose.

Raw water water pr ior to receiv ing treatment for the purpose of dr ink ing.

Regulations The W ater Supply (W ater Qual i t y) Regulat ions 2000 (England), 2010 (W ales).

Remedial act ion act ion taken to improve a s i tuat ion.

Residual disinfectant the small amount of ch lor ine or chloramines present in dr ink ing water to maintain i ts qual i t y as i t passes through the water company’s network of p ipes and household p lumbing.

Risk assessment

a review under taken to ident i f y ac tual or potent ia l hazards to human heal th in a water treatment works and assoc iated supply system. Pr ior i t isat ion of r isk is based on cons iderat ion of l ikel ihood and consequence of the r isk occurr ing.

Secretary of State Secretary of State for Environment, Food and Rural Af fairs .


67

Selenium is an essent ia l e lement and a necessary d ietary component . Amounts in dr ink ing water are usual ly wel l below the standard. A European health-based s tandard of 10μg/ l appl ies.

Service connect ion connect ion between the water company's main to a consumer’s property.

Service pipe any p ipe subject to mains water pressure or subject to mains pressure but for the c los ing of some valve.

Service reservoir a water tower, tank or other reservoir used for the s torage of treated water wi th in the d istr ibut ion system.

Sodium is a component of common sal t . I t is present in seawater and brack ish groundwater . Some treatment chemicals contain sodium. Concentrat ions in dr ink ing water are extremely low, but some water sof teners can add signif icant amounts to dr ink ing water where they are ins ta l led in homes or factor ies. A nat ional standard of 200mg/ l appl ies.

Springs groundwater appear ing at the surface at the outcrop of the junct ion of a permeable stratum with an impermeable s tratum.

Sulphate occurs natura l ly in a l l waters and is dif f icu lt to remove by treatment. An indicator parameter with a guide value of 250mg/ l .

Supply pipe see service p ipe.

Supply point a point other than a consumer ’s tap author ised for the tak ing of samples for compl iance wi th the regulat ions.

Surface water untreated water f rom r ivers, impounding reservoirs or other sur face water source.

Taste can ar ise as a consequence of natura l processes in surface waters, par t icular ly between late spr ing and ear ly autumn. W ater treatment with act ivated carbon or ozone wi l l remove natura l substances caus ing taste. The s tandard relates to the evaluat ions of a panel of people assessing samples in the laboratory.

Technical audit the means of check ing that water companies are complying wi th their statutory obl igat ions.


68

Tetrachloroethane and Trichloroethene

are solvents that may occur in groundwater in the v ic in ity of industr ia l s i tes . W here necessary they are removed by spec ia l is t t reatment. A European health-based standard of 10μg/ l for the sum of both substances applies .

Tetrachloromethane is a solvent that may occur in groundwater in the v ic in i ty of industr ia l s i tes. Where necessary i t is removed by specia l is t water t reatment. A nat ional standard of 3μg/ l appl ies .

Time of supply the moment when water passes f rom the water company’s pipework in to a consumer’s p ipework.

Total indicat ive dose is a measure of the ef fect ive dose of radiat ion the body wi l l receive f rom consumpt ion of the water . I t is calculated only when screening values for gross a lpha or gross beta (radiat ion) are exceeded. An indicator parameter wi th a guide value of 0.10mSv/year.

Total organic carbon represents the tota l amount of organic matter present in water . An indicator parameter wi th a guide value of ‘no abnormal change’ .

Toxicology the s tudy of the health ef fects of substances.

Treated water water t reated for use for domestic purposes as def ined in the regulat ions.

Trihalomethanes are formed dur ing d is infect ion of water by a react ion between chlor ine and natural ly occurr ing organic substances. Their product ion is minimised by good operat ional pract ice. A European health-based standard of 100μg/l appl ies .

Trit ium is a radioact ive isotope of hydrogen. Discharges to the environment are str ic t ly control led and there is a nat ional programme of monitor ing surface waters . An indicator parameter wi th a guide value of 100Bq/ l .

Turbidity is a measure of the c loudiness of water. At treatment works, measurement is an important non-specif ic water qual i t y contro l parameter because i t can be monitored cont inuous ly on l ine and a larms set to a lert operators to deter iorat ion in raw water qual i t y or the need to opt imise water t reatment. An indicator parameter wi th a guide value of 1NTU. When detected at the consumer’s tap i t can ar ise f rom disturbance of sediment wi th in water mains. A nat ional s tandard of 4NTU appl ies in th is case.


69

Undertakings

legal ly b inding programmes of work agreed between a water company and the Chief Inspector of Dr ink ing Water to address actual or potent ial water qual i t y issues.

Vinyl chloride may be present in p las t ic pipes as a res idual of the manufactur ing process of polyviny l chlor ide (PVC) water p ipes. I ts presence in dr ink ing water is contro l led by product spec if icat ion. A European health-based standard of 0.5μg/ l appl ies .

Water supply zone a pre-def ined area of supply for establ ish ing sampl ing f requenc ies, compl iance wi th s tandards and informat ion to be made publ ic ly avai lable.

WHO World Health Organisat ion.

Wholesome/wholesomeness a legal concept of water qual i t y which is def ined by reference to s tandards and other requirements set out in the regulat ions.


70

Annex 3 Not significant and minor drinking water quality events

Nature Number of not signif icant and minor events Area a ffected (est imate of populat ion affected)

Chemical 1 – DW R (1) Yst radgynla is , Swansea (3)

Discolourat ion 4 – DVW (1) , DW R (3) Br i thd i r , Caerphi l ly (11,250) Conwy, Gwynedd (5,000) Haverfordwest , Pembrokeshi re (1 ,750) Borras, W rexham (6,605)

Heal th concern 1 – DVW (1) Wrexham (43,773)

Loss of suppl ies / poor pressure

1 – DW R (1) L lanarmon-yn- la l , Denbighshi re (435)

Microbio log ica l 2 – DW R (2) Connah’s Quay, F l in tsh i re (3) Ear lswood, Monmouthshi re (2)

Publ ic concern 4 – DW R (3) , SVT (1 ) L lawr-y-Glyn, Powys (83) Cymmer, Por t Ta lbot (5) Penyf fordd, F l in tsh i re (5 ) L lantr isant , Rhondda Cynon Taf f (3 )

Taste o r odour 5 – DW R (4) , SVT (1 ) Pontdolgoch, Powys (3) Rhoscrowther, Pembrokeshi re (5) Clynnog Fawr, Gwynedd (3) L langernyw, Conwy (3) L lanbradach, Caerphi l l y (3)

Total 18 –DVW (2) , DWR (14) , SVT (2 ) 68,934


71

Significant, serious and major drinking water quality events

Date and durat ion

Area Estimate of populat ion affected

Nature and cause of the event

Main act ions and f indings from the Inspectorate investigat ion

24 May 2011 For 24 hours (DW R)

Single property concess ionary supply in Fel indre, Swansea

3 Microbio log ica l contaminat ion.

Dŵr Cymru Welsh Water act ion:

Issued a boi l wate r not ice.

Sampled af fected a rea.

Provided bot t led wate r .

Adjusted in le t va lve to po int o f use t reatment device to improve contact t ime .

Invest igat ing capi ta l investment opt ions for upgrading or rep lac ing the point o f use device.

DWI comments and f indings:

Inadequate t rea tment process – d is in fect ion.

Cr i t ica l that th is is the four th occas ion when th is supply has been subject to bo i l water advice .

Noted that the owner had turned of f the point o f use device and th is was the l ike ly cause of the detec t ion of E.col i .

Risk c lass i f icat ion: Sign i f icant .

01 Ju l 2011 For 3 days (DVW )

Chester and North East Wales

102,000 Microbio log ica l contaminat ion.

Dee Val ley Water Plc act ion:


Inspected reservo i r .

Increased ch lor ine res iduals leaving the works.


Dur ing a post event audi t the Inspectora te found s ign i f icant def ic ienc ies wi th s torage of water in the tower.

The company had fa i led to act on the Inspectorate ’s recommendat ions f rom a previous audi t and even t assessment .

Not ice in p lace and the company are current l y work ing wi th the Inspectorate to agree the cont ro l measures and act ions to mi t igate a recurrence.



72

Date and durat ion




20 Ju l 2011 For 20 days (DVW )

Glan Garth, Wrexham

3 Taste and odour, and i l lness compla in t .

Dee Val ley Water Plc act ion:


F lushed mains.

Carr ied out a water f i t t ings inspect ion. DWI comments and f indings:

No recommendat ions or suggest ions made.

No l ink made be tween reported i l lness and water supply. Risk c lass i f icat ion: Sign i f icant .

30 Ju l 2011 For 24 hours (DW R)

L langewydd, Br idgend



F lushed mains.


Carr ied out severa l wate r f i t t ings inspect ions at propert ies in the area .


No recommendat ions or suggest ions made. Risk c lass i f icat ion: Sign i f icant .

17 Aug 2011 For 1 day (DW R)

Areas of North East W ales suppl ied by Bret ton and Alwen works



Col lec ted fo l low-up samples.

Carr ied out labora tory audi ts .

Enhanced envi ronmenta l moni tor ing of laboratory .

Modi f ied p rocedures. DWI comments and f indings:

Cr i t ica l o f the or ig in of the problem ( laboratory contaminat ion) but content wi th the company handl ing of the even t and act ions taken.



73

Date and durat ion




27 Aug 2011 For 36 hours (DW R)

North W est Swansea, inc lud ing Penl lergaer, Pontardula is and Waunar lwyd and surrounding areas

231,000 Brown d isco lourat ion. Dŵr Cymru Welsh Water act ion:


F lushed mains.

Repai red fau l ty equipment . DWI comments and f indings:

Th is event was caused by a s tuck bal l va lve in Cocket t reservo i r suddenly re leas ing caus ing a surge in f low.

No recommendat ions or suggest ions made.


08 Oct 2011 For 2 days (DW R)

Ely and Caerau a reas of Card i f f

2 ,100 Discolourat ion due to a burs t main and media in terest .


Repai red main.


Rezoned area (brought in water f rom d i f fe rent source) .

F lushed the system to m i t igate the ef fects of d isco loured water .


Inadequate r isk assessment .

Recommended that appropr ia te r isk assessments are a lways carr ied out pr ior to act ions being t aken on the d is t r ibut ion network.



74

Annex 4 Planned drinking water quality improvements Company

Parameter, hazard or dr iver

Site Due for complet ion*

Status* Legal Instrument

DVW E.col i Boughton 31-Mar-14 Ongoing Not ice

DVW Ingress L lwyn Onn 31-Sep-11 Completed

04-Aug-11 Not ice

DVW Manganese Legacy 31-Mar-13 Ongoing Not ice

DVW Manganese Wrexham 31-Dec-13 Ongoing Undertak ing

DVW Manganese, Cryptospor id ium

L lwyn Onn 30-Jun-13 Ongoing Not ice

DW R Alumin ium Ponts t ic i l l 31-Mar-12 Completed

31-Mar-12 Undertak ing

DW R Col i form bacte r ia and E.col i

L lyswen 31-Ju l -12 Ongoing Not ice

DW R Cryptospor id ium Abergynolwyn 31-Mar-11 Completed 31-Mar-11

Not ice

DW R Cryptospor id ium Brecon

28-Feb-10 (UV)

31-Mar-11

Completed 26-Feb-10

Delayed

Not ice

DW R Cryptospor id ium Bui l th 31-Oct-08 Completed

30-Apr-11 Not ice

DW R Cryptospor id ium Concess ionary supply (1 )

31-Aug-12 Ongoing Not ice

DW R Cryptospor id ium Dinas Mawddwy 31-Mar-11 Completed

31-Mar-11 Not ice

DW R Cryptospor id ium Llannerch 30-Jun-13 Ongoing Not ice

DW R Cryptospor id ium Ll id iardau Bala 30-Sep-12 Ongoing Not ice

DW R Cryptospor id ium Llyn Conwy 31-Mar-13 Ongoing Not ice

DW R Cryptospor id ium Pendine 30-Jun-10 Completed

30-Sep-11 Not ice

DW R Cryptospor id ium and Colour

Cantref 31-Mar-13 Ongoing Not ice

DW R Cryptospor id ium and Tota l Tr iha lomethanes

Capel Cur ig 31-Mar-11 Completed

30-Sep-11 Not ice


Ci l for F ina l 30-Sep-11 Completed

04-Oct-11 Not ice

DW R Cryptospor id ium

and Tota l Tr iha lomethanes

Cwmystrad l l yn 30-Dec-13 Ongoing Not ice


Ei th in Fynydd 31-Mar-11 Completed 31-Mar-11

Not ice


Penycefn 30-Sep-11 Completed

30-Sep-11 Not ice

DW R

Cryptospor id ium,

Col i form bacte r ia , E.col i and Manganese

Alwen New 31-Aug-11 Completed

24-Aug-11 Not ice


75

Company Parameter, hazard or dr iver



DW R

Cryptospor id ium , power supply and Tota l Tr iha lomethanes

Sluvad 31-Mar-15 Ongoing Not ice

DW R Further invest igat ion requi red

Concess ionary supply (3 )

31-Mar-15 Ongoing Not ice

DW R Inadequate d is in fect ion

Concess ionary supply (4 )

31-Dec-13 Ongoing Not ice


Dorstone 31-Dec-13 Ongoing Not ice


Strata F lo r ida 31-Mar-12 Delayed Not ice

DW R Ingress Onnen Asaph 31-Dec-10 Delayed Not ice

DW R Ingress Pengarnddu 31-Mar-16 Ongoing Not ice

DW R Ingress Rhiwbina 31-Mar-15 Ongoing Not ice

DW R Ingress Tafa rnaubach 31-Mar-12 Delayed Not ice

DW R Ingress Wern 31-Mar-11 Delayed Not ice

DW R Inspect ion and repai r

Bedwas 31-Mar-15 Ongoing Not ice

DW R Inspect ion requi red

Water loo 31-Dec-12 Ongoing Not ice

DW R Iron Penarth/Barry 31-Mar-11 Delayed Not ice

DW R Iron Penarth/Barry 31-Mar-16 Ongoing Not ice

DW R Iron Penderyn 30-Nov-09 Completed

19-Sep-11 Not ice

DW R Manganese Bwlch Area and Abergavenny/ Cwmti l lery

31-Dec-11 Delayed Undertak ing

DW R Manganese L lyn Conwy 30-Sep-13 Ongoing Not ice

DW R Manganese Townhi l l and Cra i /Clydach

31-Ju l -15 Ongoing Undertak ing

DW R Pathogens L lan Y Mawddwy


DW R Poss ib le abandonment

Beggars Bush 31-Mar-15 Ongoing Not ice


Bryneglwys and Corwen

31-Dec-11 Completed

16-Dec-11 Not ice


Pydew 31-Mar-15 Ongoing Not ice

DW R Repai r or abandonment

Ganl lwyd 31-Dec-12 Ongoing Not ice

DW R Short c i rcu i t ing Gwel fo r Rd 31-Dec-11 Delayed Not ice

DW R Var ious Alaw 31-Dec-14 Ongoing Not ice

DW R Var ious Bont Goch 31-Mar-15 Ongoing Not ice

DW R Var ious Bret ton 31-Mar-13 Ongoing Not ice

DW R Var ious Bryn Cowlyd 31-Dec-13 Ongoing Not ice

DW R Var ious Bryngwyn 31-Dec-13 Ongoing Not ice

DW R Var ious Cefn i 31-Dec-13 Ongoing Not ice


76

Company Parameter, hazard or dr iver



DW R Var ious Concess ionary supply (10)


DW R Var ious Concess ionary supply (11)


DW R Var ious Concess ionary supply (5 )










DW R Var ious Garreglwyd 31-Mar-15 Ongoing Not ice

DW R Var ious Glascoed 31-Mar-16 Ongoing Not ice

DW R Var ious Nant Per is 31-Mar-13 Ongoing Not ice

DW R Var ious New Presel i 31-Mar-14 Ongoing Not ice

DW R Var ious Port is 31-Mar-16 Ongoing Not ice

*Dates used are those for the complet ion of the agreed programme of work. There is a fur ther per iod of 12 months before a p rogramme is o f f ic ia l ly c losed to ascer ta in the benef i ts o f the work to consumers.

Delayed programmes

Company Parameter, hazard or driver

Site Reason for de lay

DW R Cryptospor id ium Brecon Change of so lu t ion


Strata F lo r ida Resource issues

DW R Ingress Onnen Asaph Weather condi t ions

DW R Ingress Tafa rnaubach Design issues - ins ta l la t ion

DW R Ingress Wern Design issues - addi t ional work

DW R Iron Penarth/Barry Des ign issues - model l ing work

DW R Manganese Bwlch Area and Abergavenny/ Cwmti l lery

Planning and des ign issues

DW R Short c i rcu i t ing Gwel fo r Rd Contract issues

Acknowledged actions to sustain safe, clean drinking water

Additional acknowledged act ions to mit igate risk

(as at Dec 2008)

Acknowledged act ions completed

(as at Dec 2010)

Acknowledged act ions completed

(as at Dec 2011)

310 35 127


77

Annex 5 Competition in the water industry

The following table indicates the extent of competit ion in the water industry in England and Wales .

Inset appointments in place in 2011

Site Appointee Incumbent and region Status

Shotton Paper , Shotton

Alb ion W ater Dŵr Cymru W elsh W ater , Wales

Supplying water

Buxted Chicken, Fl ix ton

Angl ian W ater Essex and Suf fo lk W ater, Centra l and Eastern region

Supplying water

W ynyard, near Wolviston

Har t lepool Water Nor thumbr ian W ater, Nor thern region

Supplying water

Berryf ie lds , Aylesbury

Independent Water Networks Ltd

Thames Water, London and South East region

Supplying water

Brook lands, Mi l ton Keynes


Angl ian W ater, Centra l and Eastern region

Supplying water

Great Bi l l ing W ay, Nor thampton



Supplying water

Kings Cross, London



Supplying water

Long Crof t Road, Corby



Supplying water

Pr iors Hal l , Corby Independent Water Networks Ltd


Supplying water

The Br idge, Dar tford



Supplying water

Media City, Salford Quays

Peel Water Networks Ltd

Uni ted Ut i l i t ies, Nor thern region

Supplying water

Bromley Common, Bromley

SSE W ater Thames Water, London and South East region

Supplying water

Farndon Road, Market Harborough

SSE W ater Severn Trent W ater/ Angl ian Water, Centra l and Eastern region

Supplying water

Grayl ingwel l , Chichester

SSE W ater Portsmouth W ater/Southern Water, London and South East region

Supplying water

Great Western Park , Didcot


Supplying water

Hale Vi l lage, Tottenham


Supplying water

Kennet Is land, Reading


Supplying water

Kingsmere, Bicester


Supplying water

L lani l id Park , South W ales

SSE W ater Dŵr Cymru W elsh W ater, Wales

Supplying water

New South Quarter, Croydon


Supplying water

Park Views, Epsom


Supplying water


78

Site Appointee Incumbent and region Status

Rivers ide, Bark ing SSE W ater Essex and Suf fo lk Water/Thames W ater, Centra l and Eastern region

Supplying water

The Portway, near Sal isbury

SSE W ater Wessex W ater, Western region

Supplying water

Fair f ie ld Park and Lower W ilbury Farm, Ar lesey

Veol ia W ater Centra l


Supplying water

MoD T idworth near Andover

Veol ia W ater Projects

Wessex W ater, Western region

Supplying water

New inset appointments in 2011

Site Appointee Incumbent and region

Status

Kennet Is land (Phase 7) , Reading


Appointment granted


79

Annex 6 Water company indices

Albion Water Limited


Company assets Water supplied

Number of treatment works 0 Water suppl ied ( l /day)

36,000

Number of service reservoirs 0 Percentage f rom surface sources

100

Number of water supply zones 1 Percentage f rom ground sources

0

Length of mains p ipe (km) 0 Percentage f rom mixed sources

0

Population served Area of supply

Flintshire Populat ion supplied 300

Number of local author it ies 1

Drinking water quality summary data

Company f igure Industry average

2009 2010 2011 2011

Overal l drinking water quality* 100% 100% 100% 99.96%

Water t reatment

Process Contro l Index N/A N/A N/A 99.99%

Dis infect ion Index N/A N/A N/A 99.97%

Distribution systems

Dis tr ibut ion Maintenance Index 100% 100% 100% 99.88%

Reservoir In tegr i ty Index N/A N/A N/A 99.96%

Building water systems

Parameters inf luenced by domest ic water systems

100% 100% 100% 99.87%

Consumer contacts


2009 2010 2011 2011

Informing consumers

Total number 0 0 0 N/A

Rate per 1 ,000 populat ion 0 0 0 1.21

Acceptabi l ity of water to consumers

Tota l number 0 0 0 N/A

Rate per 1 ,000 populat ion 0 0 0 1.91

Complaints to the Drinking Water Inspectorate

No consumers of Alb ion W ater L imited d irec t ly contacted DWI in 2011.

Note: Summary resu l t s for each company o f tes ts for i nd i v idua l parameters are supp l ied on the DW I webs i te a t h t tp : / /www.dwi .gov.uk

* Overa l l d r ink ing water qua l i t y as rep resented by mean zona l compl iance fo r 39 parameters .

http://www.dwi.gov.uk/


80

Dee Valley Water plc



Number of treatment works 6 W ater suppl ied (Ml/day)

66


94


6

Length of mains p ipe (km) 1,857 Percentage f rom mixed sources

0


Cheshire, Fl intshire, Denbighshire and Wrexham

Populat ion supplied 270,000




2009 2010 2011 2011

Overal l drinking water quality* 99.99% 99.89% 99.94% 99.96%

Water t reatment

Process Contro l Index 100% 100% 100% 99.99%

Dis infect ion Index 99.90% 99.87% 99.82% 99.97%


Dis tr ibut ion Maintenance Index 99.92% 99.95% 99.67% 99.88%

Reservoir In tegr i ty Index 99.82% 99.97% 100% 99.96%



99.93% 99.76% 99.82% 99.87%

Consumer contacts


2009 2010 2011 2011

Informing consumers


Rate per 1 ,000 populat ion 0.71 0.59 0.32 1.21





No consumers of Dee Val ley W ater plc di rec t ly contacted DWI in 2011.





81




Number of treatment works 87 Water suppl ied (Ml/day)

770


95


4


1


Conwy, Anglesey, Blaenau Gwent, Bridgend, Gwynedd, Caerphil ly, Cardiff , Cardiganshire, Carmarthenshire, Denbighshire, Flintshire, Merthyr Tydf il , Monmouthshire, Neath and Port Talbot, Newport, Pembrokeshire, Powys, Rhondda Cynon Taff , Swansea, Torfaen, Vale of Glamorgan, part of Herefordshire

Populat ion supplied 2,955,000




2009 2010 2011 2011


Water t reatment

Process Contro l Index 99.94% 100% 99.96% 99.99%




Reservoir In tegr i ty Index 99.95% 99.97% 99.97% 99.96%



99.89% 99.95% 99.90% 99.87%

Consumer contacts


2009 2010 2011 2011

Informing consumers

Tota l number 5,226 3,687 1,486 N/A



Tota l number 12,439 9,882 9,011 N/A



A tota l of 3 consumers of Dŵr Cymru W elsh Water d irect ly contacted DW I in 2011.





82

Severn Trent plc Water supply arrangements


Number of treatment works 185 Water suppl ied (Ml/day)

1,853


64


33


3


Derbyshire, Nottinghamshire, Leicestershire, Warwickshire, Gloucestershire, Worcestershire, Shropshire, Staffordshire, West Midlands, Powys

Populat ion supplied 7,775,000




2009 2010 2011 2011


Water t reatment

Process Contro l Index >99.99% 99.99% 99.99% 99.99%




Reservoir In tegr i ty Index 99.98% 99.98% 99.96% 99.96%



99.90% 99.94% 99.93% 99.87%

Consumer contacts


2009 2010 2011 2011

Informing consumers

Total number 942 685 1,058 N/A



Tota l number 11,887 12,169 11,848 N/A



A tota l of 4 consumers of Severn Trent p lc d i rect ly contacted DWI in 2011.





83

SSE Water Water supply arrangements


Number of treatment works 0 Water suppl ied ( l /day)

0.661


39


48

Length of mains p ipe (km) 22 Percentage f rom mixed sources

13


Old Sarum, near Sal isbury;

Hale Vi l lage, Tottenham; Grayl ingwell , Chichester; Bromley Common, Bromley; Kennet Island, Reading; Park Views, Epsom; Llani l id Park, South Wales; Kingsmere, Bicester; Great Western Park, Didcot; Barking Riverside, Barking; Farndon Road, Market Harborough

Populat ion supplied 5,000




2009 2010 2011 2011

Overal l drinking water quality* 100% 100% 100% 99.96%

Water t reatment

Process Contro l Index N/A N/A N/A 99.99%

Dis infect ion Index N/A N/A N/A 99.97%


Dis tr ibut ion Maintenance Index 100% 100% 100% 99.88%

Reservoir In tegr i ty Index N/A N/A N/A 99.96%



100% 100% 100% 99.87%

Consumer contacts


2009 2010 2011 2011

Informing consumers

Total number 1 1 2 N/A




Rate per 1 ,000 populat ion 0 0.99 0.39 1.91


No consumers of SSE Water d irect ly contacted DW I in 2011.





84

Annex 7 Information relating to public water supplies published by the Inspectorate in 2011 Information Letters

Ref Title

01/2011 Amendment to The Water Supply (Water Quality) Regulat ions

2010 (Wales)

02/2011 DWI Enforcement Policy

03/2011 Publ icat ion of World Health Organisat ion (WHO) document

entit led 'Water safety in bui ldings'

04/2011 Guidance on the general provisions for monitor ing of parameters

relevant to radioactivity

05/2011 Product ion, delivery, receipt and control of water treatment

chemicals

06/2011 Technical Audit of Water Companies under Section 86 of the

Water Industry Act 1991: Publ icat ion of the report following the

audit of STS Analyt ical Services at Br idgend

07/2011 Implementat ion of the new SCA blue book 233: The

determination of taste and odour in dr inking waters (2010)

08/2011 Publ icat ion of report: Object ionable taste and od our in water

suppl ies in North-East London between January and March 2010

The le t te rs , and the i r assoc ia ted annexes , can be found on the Inspec tora te ’s webs i te a t ht tp : / /dwi .def ra .gov.uk /s takeholders / i n format ion - l e t te rs / index.h tm

Technical guidance

DWI Approval of Enterolert -DW® Quanti-Tray® method for the

determination of Enterococci in dr inking waters

Copies o f the above gu idance can be found on the Inspec tora te ’s webs i te a t ht tp : / /dwi .def ra .gov.uk /s takeholders /gu idance -and -codes -o f -p rac t ice /


85

Research

Ref Tit le

DWI 70/2/260 Alternatives to phosphate for plumbosolvency control

DWI 70/2/245 Investigation of instances of low or negative pressures in

UK dr inking water systems

DWI 70/2/224 Analyt ical methods for predicted dis infect ion by -products

of probable toxicological s ignif icance

DWI 70/2/242 Evaluat ion of haloacetic acid concentrat ions in treated

drinking water (Cranf ield University)

DWI 70/2/253 Evaluat ion of haloacetic acid concentrat ions in treated

drinking water (WRc plc)

DWI 70/2/255 A review of fungi in drinking water and the implicat ions for

human health

DWI 70/2/208

WRF 4006

Crit ical assessment of implement ing desal inat ion

technology

DWI 70/2/225 An invest igation of leaching f rom f lexible r ising mains

leading from borehole pumps

DWI 70/2/189 Water Safety in Bui ldings

Copies o f res earch repo r ts and exec ut ive summar ies can be found on the Inspec tora te ’s webs i t e at h t tp : / /dwi . def ra .gov.uk / researc h/comple ted - res earch/2000todate .h tm


86

Annex 8 Distribution of private water supplies


87

Local authori t ies Key

Is le o f Anglesey County Counci l 1

Gwynedd County Counci l 2

Conwy County Borough Counci l 3

Denbighshi re County Counci l 4

F l in tsh i re County Counci l 5

Wrexham County Borough Counci l 6

Pembrokeshi re County Counci l 7

Ceredig ion County Counci l 8

Carmarthenshi re County Counci l 9

Powys County Counci l 10

Swansea Ci ty and Borough Counci l 11

Neath Port Ta lbo t County Borough Counci l 12

Br idgend County Borough Counci l 13

Rhondda Cynon Taf f County Borough Counci l 14

Merthyr Tydf i l County Borough Counci l 15

Caerphi l l y County Borough Counci l 16

Blaenau Gwent County Borough Counci l 17

Torfaen County Borough Counci l 18

Monmouthshi re County Counci l 19

Vale of Glamorgan Counci l 20

Card i f f Counci l 21

Newpor t Ci ty Counci l 22

Drinking Water Inspectorate | 55, Whitehall | London | SW1A 2EY | Tel: 020 7270 3370

http://www.dwi.gov.uk

Drinking Water Inspectorate | Ergon House, Horseferry Road | London | SW1P 2AL | Tel: 0300 068 6400

www.dwi.gov.uk

PB 13778

Drinking water2011Public water supplies in WalesJuly 2012A report by the Chief Inspector of Drinking Water

Drinking water 2011

Public water supplies in W

ales

drinking water 2011 - gov.ukdwi.defra.gov.uk/about/annual-report/2011/wales.pdf · cynon taff,...

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