water management & conservation - malaysia green · pdf file• rain events...

Water Management

Ir. Lam Kim Seong March 2013

& ConservationRainwater Harvesting

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RAINWATER HARVESTING

Projected Water Demand

10,000

11,000

12,000

10582

Projected Water Demand

in Peninsular Malaysia

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6,000

7,000

8,000

9,000

10,000

2010 2020

Domestic

Industrial

Mil

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Year

8184

7101

9756

Source: NPP Infrastructure and Utilities

Technical Report, 2001 in Federal Dept. of

Town and Country Planning, 2005

Uneven people-water distribution

• Development/Industrialization

• Population growth

• People migration

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In densely populated states, demand continues to rise but river

basins have reached their limit for maximum supply

For Selangor, there are four main sources of raw water for

processing into potable water and all has been utilized

• People migration

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One of the most precious resources taken for granted

Water wastage

Average domestic water consumption in Malaysia is higher than

that of developed countries (eg. 226 litres per person per day

(LPD) in Selangor and 274 LPD in Penang) compared to best

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Average consumption in Selangor including water used outside

the home (workplace, school, etc) is > 300 LPD. The international

standard for recommended water usage is 165 LPD1

[1] School of Humanities, USM, Malaysia

(LPD) in Selangor and 274 LPD in Penang) compared to best

practice (100 LPD - Czech Republic) and more than twice the

average of Singapore, Australia or UK

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Inte

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Inte

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INTENT

To encourage rainwater harvesting the will lead to reduction in potable

water consumption

WHAT ARE THE ADVANTAGES?

Environmental

Inte

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Inte

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• Reduces demand on treated water

• Reduces soil erosion & flooding caused by runoff

• Reduces peak flow discharge to drainage system

• One of the purest water source

• Not exposed to contaminants in the ground

• Rainwater is soft water

Environmental

Qualitative

Rainwater harvesting from rooftop catchments for use in cistern storage is not new. It has been an important source of water supply for domestic purposes in many rural areas in the past

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• 3 pilot projects carried out; Government office, Mosque and a residential house

• Designing and installing RW harvesting system for several schools

In 2004 NAHRIM (National Hydraulic research Institute of Malaysia) was established to conduct research of water hydraulic and water environmentF

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Malaysia is endowed with far more rainfall than our water demand

when compared with other countries.

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RAINWATER HARVESTINGFe

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NRNC

Achieve the following percentage reduction in potable water consumption:

• 1 point: For 15% or more

GBI Water Efficiency – Rainwater Harvesting

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• 2 points: For 30% or more

RNC

Achieve the following percentage reduction in potable water consumption:





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Depending on the type of buildings, potable water usage may

include the following applications:

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Potable Water

The baseline consumption refers to all treated (potable) water

taken from the water mains


• Toilets

• Landscape irrigation

• F&B

• Cooling tower make-up

• Swimming Pools and Water Features

• Laundry

• General Washing

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Factors that affect Rainwater Harvesting Design

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• Daily rainfall intensity

• Rain events distribution

- continuous rainy days

- dry spells

RAINWATER HARVESTINGS

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- dry spells

• Available catchment

• Building water usage pattern

• Storage tank size

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Excess/overflow from heavy downpour or continuous rainy days (affected by the size of storage tank provided)

Unaccounted potable water use during prolonged dry spells

Rainfall - uncontrollable


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Source: Jabatan Pengairan dan Saliran Malaysia

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Catchment

Site/building design – catchment area constraint

Low rise

- high catchment/usage ratio


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- high catchment/usage ratio

High rise

– low catchment/usage ratio

– RWH design more challenging

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Building Water Consumption

Building type dependent

• Residential

• Non-residential (office, shopping etc.)


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- Office (5 or 6-day week)

- Residential (7-day week)

- Retail/Hotels (7-day week)

- Irrigation (daily except rain event days)

Factors to consider are hours of occupancy and days of operation

� building baseline consumption is not addressed

Effectiveness of RW Harvesting is limited if:

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� harvested rainwater is not effectively used

Type of usage

• Garden Irrigation

• Toilet flushing

• Others (Air conditioning make-up, etc.)

Increased Usage High RWH ratio

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nt Principles of Water Management

� Conserve water

� Reuse water

RAINWATER HARVESTINGW

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� Reuse water

� Know where and how water is used

� Continuous evaluation of water use

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Baseline potable water consumption has to be

improved.

� Use of water efficient fittings

For an effective of RW Harvesting system:

RAINWATER HARVESTINGB

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� Use of water efficient fittings

� Improve air conditioning system

design to reduce AC make-up water

requirement

� Waste water recycling

� AC condensate water recovery

Water Closets

> 6L per flush - inefficient

< 6L per flush – good

< 4.5L per flush - excellent

Urinals

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> 2L per flush - inefficient

Water Efficient Fittings


< 4.5L per flush - excellent

Tap Fittings

> 6 L/min – inefficient

< 6 L/min – good

< 4 L/min - excellent

Shower heads

> 9 L/min – inefficient

< 9 L/min – good

< 6 L/min - excellent

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< 2L per flush – good

< 1L per flush - excellent

Water Conservation

Select low-flow water efficient fittings

Water usage in cooling towers:

Cooling Tower water make-up

1. Evaporation

2. Bleed

3. Drift losses

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3. Drift losses

Evaporation

• Normal process

• To remove heat from the condenser water

Drift Loss

• Water lost due to water droplets entrainment in the air stream.

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Bleeding (blow-down)

• Controlled draining of water to prevent built-up of dissolved and suspended solids (to prevent corrosion and scaling)

• Dependent on quality of make-up water and effectiveness of water treatment system.

• Based on cycle of concentration (ratio of concentration of the

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Water Conservation

Improved air conditioning system design:

• Reduced cooling load to lower condenser water flowrate

• Select /specify low drift-loss cooling towers

• Based on cycle of concentration (ratio of concentration of the dissolved solids in the condenser water to that of the make up water)

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Water Consumption comparison between baseline and design case


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Description Baseline Design

Potable Water Consumption 40,556 22,090

Greywater Recycling - 4,176

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Greywater Recycling - 4,176

Resultant Potable Water Consumption 40,556 17,914

Rainwater Harvesting 2,910 2,910

Ratio of RWH/Potable Water Consumption (%) 7.2% . 16.2% .

Total Potable Water Consumption 37,646 15,005

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Rainwater Harvesting System Components

Pre-storage filtration

Catchment

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Storage

Post-storage filtration

Treatment

Operation

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Catchment

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Pitched Tile Roof Metal Roof

RC Flat Roof Block Pavement

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Pre-storage filtration

The first rainfall may contain higher than average amounts of accumulated dust, industrial pollutants, bird and animal droppings, leaves and other debris, pre-storage filtration shall be provided to prevent risk of contaminants affecting rainwater quality.

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rainwater quality.

- Install on downpipes to remove leaf and debris

Depending on the type of catchment area and the intended use of the rainwater, filtration may be required.

Leaf and debris screen

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First Flush

- Divert minimum 1mm of initial rainfall with first flush diverter or other suitable means

- Divert higher volume

First flush diverter to improve rainwater quality.

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Exercise

- Divert higher volume of first flush rainwater if substantial pollution expected. C

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Post-storage filtration/treatment may not be required if the rainwater is used for garden watering or car wash.

For toilet flushing, laundry or similar uses, suitable method of filtration has to be provided to safeguard against odour, sediment and discolouration that may affect appliances or clothing.

Post-storage Filtration/Treatment

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and discolouration that may affect appliances or clothing.

Post-storage treatment includes:

- Sediment filtration (remove suspended solids)

- Activated carbon (taste/odour/colour)

- Fine micron or membrane filtration (if human contact or consumption is envisaged)

- UV light treatment (if human contact or consumption is envisaged)

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Design approach:

Intended use

Rainfall data

Available/required catchment

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Pre-treatment (first flush diversion amount)

Above in turn determines the size of rainwater storage tank required.

Catchment type (run-off coefficient)

Available/required catchment

Rainwater Harvesting applications

Landscape Irrigation

Toilet flushing

Laundry

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Laundry

Others

• pools/ponds make-up

• cooling tower make-up

• general washing

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Increased Usage High RWH ratio

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Rainfall Data

Daily rainfall data can be obtained from JabatanPengairan dan Saliran Malaysia


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With the defined catchment area, type of catchment and the

Collectible Rainwater

Dependent on:

• Catchment area

• Type of catchment


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With the defined catchment area, type of catchment and the rainfall data, the following Rainwater Collection Calculation formula can be used to estimate the amount of rainwater that can be captured.

Rainfall Catchment Run-off Amount Litres of

in x area x Coefficient - diverted = rainwater

(mm) (m2) (%) (L) captured

Thank youThank you

Ir. Lam Kim Seong

Prudenergy Consulting Sdn Bhd

[email protected]

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