Rainwater Harvesting Guide for Malaysians

8/9/2019 Rainwater Harvesting Guide for Malaysians

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A Guide

ToRainwater

Harvesting inMalaysia

Written By:

Jitender Dev SehgalPresident 2005 06

Rotary Club of Johor Bahru4N Susur3, Jalan Tun Abdul Razak,80000 Johor Bahru, Johor, Malaysia

This booklet is distributed as a Community Service byRotary Club of Johor Bahru, District 3310 of RotaryInternational. Contents of this booklet may be copied freelywith acknowledgement of the source, and used only for freedissemination of information to public.

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FOREWORD

Carl-Wilhelm Stenhammar, 2005 06 President of

Rotary International, in his Theme Address to 2005

International Assembly at Anaheim, USA, stated that

The United Nations calls the global water crisis a

threat to economic development, to povertyreduction, to the environment, and to peace and

security. and more than one billion people dont

have clean, safe drinking water. He urged theRotarians all over the world to do what they can and

improve the availability of clean water in the world.

The Author, Rotarian Jit Sehgal, in this year of his

Presidency of the Rotary club of Johor Bahru, inspired

by the RI President, has written this guidebook to

remind Malaysians on how to harness this primary

natural resource of clean water that is delivered free

to our rooftops, by Mother Nature. The author is ahighly qualified chemical engineer, with more than

fifty years of experience in industry and is eminently

positioned to research and write on this topic. The

content of this booklet deserves serious attention by

all.

Although the Country enjoys abundant resource of

fresh water, already there are areas where water

supply becomesinadequate, and rationing is resortedto. Following the guidelines of this booklet, no doubt,

will benefit the population, and the environment as

stated in the booklet, both in the short and long term.

Ir John Cheah Kam Loong P.I.S Johor Bahru

Past District Governor 1990-91 November 19, 2005

Rotary International District 3310

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Introduction

Water is an essential component forsustaining life. Life on our planet as weknow it would not have come into beingwithout it, nor can it be sustained in theabsence of water. Our bodies consist

mostly of water. We need water fordrinking, cooking, washing, agriculture,to run our industries, and fortransportation on the waterways, and ina myriad other ways that form part of oureveryday living. For as long as water isabundantly available, we take it for

granted; when in scarcity however itbecomes our most precious resource. Askany desert dweller about water tounderstand its real value.

Did you know that although 70% of ourearth is covered with water, only 3% of

this water is fresh? Out of this, 2% islocked up in the form of ice, and it is onlythe balance 1% of water that recyclesthrough the evaporation / condensationcycle, that flows into the rivers and lakes,to be used by mankind.

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The history of rainwater harvesting inAsia can be traced back to about the 9th

or 10th Century to the small-scalecollection of rainwater from roofs andsimple brush dam constructions in therural areas of South and South-east Asia.Rainwater collection from the eaves ofroofs or via simple gutters into traditional jars and pots has been traced back

almost 2,000 years in Thailand.Rainwater harvesting has also long beenused in the Loess Plateau regions ofChina.

In Malaysia, we are blessed with anample supply of water thanks to

abundant rains. However, increasingusage by our industry, in agriculture andby household users is straining ourexisting water supply infrastructure. Thecosts of adding to this infrastructure andthat of replacing the ageing system arefurther burdening our Exchequer.

At present we primarily depend uponrainwater that falls over the hills and inthe countryside and which is thencollected into large reservoirs and asground water. This water is thenpumped into treatment plants and from

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there distributed through the watermains and a network of pipes.

However perhaps we should pause tothink that clean water is also beingdelivered to us right on our roof tops asrain but that we let this run off into stormwater drains, where it ends up causingflooding and soil erosion on its way to the

rivers and sea. In fact, the rainwaterfalling on our rooftops is one of thepurest forms of natural water that natureprovides us, yet we simply let it flowaway.

This booklet presents some useful

information on rainwater, and aims toprovide an understanding of many of therelevant aspects of rain with a view toharvesting it for both domestic andindustrial use directly from our rooftops,thereby allowing us to benefit from thisbountiful resource delivered free to us by

nature. A simple method of harvestingrainwater, storing and using it isdescribed.

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The Water Cycle

The never-ending exchange of waterfrom the atmosphere to the oceans andback again is known as the hydrologiccycle. All forms of precipitation (hail, rain,sleet, and snow), and consequently allmovement of water in nature, forms part

of this cycle.

Precipitation stored in streams, lakes andin soil evaporates while water stored inplants transpires to form clouds, whichboth absorb solar heat and form thestore of water in the atmosphere. When

the atmospheric conditions reach a levelof super saturation, a state achieved as aresult of increased humidity combinedwith changes in temperature andpressure, this water is released in theform of rain, sleet, snow or hail, whichfalls as a result of the force of gravity to

the earth.

This cycle continues, and results inshifting water from sea level all the wayinto the mountains and back into rivers,lakes and the sea etc.

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Quantitative estimates of water

resource in Malaysia

According to the InternationalCommission on Irrigation andDrainage1 Rainfall (in Malaysia)generally occurs throughout the year, butthere is some concentration due to the

North-East and South-West monsoons.The mean annual rainfall averages about2,300 mm, while the annual potentialevaporation averages about 1,500 mm.

The total annual surface water resourceis estimated to be 566,000 million KL per

year and of this 26 % is in PeninsularMalaysia, 54 % in Sarawak, and theremaining 20 % in Sabah. Groundwaterresource is estimated to have a safe

yield of 14,700 million m3 per yearin Peninsular Malaysia, 5,500 millionKL per year in Sarawak, and 3,300 million

KL per year in Sabah.

The present annual total consumptiveuse of water is estimated to total 10,400million KL for irrigation. 4,900 million KLfor domestic and industrial water supply.On the whole, Malaysia has sufficientwater resources for development to meet

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all the demand provided there is proper water resources

development, conservation andmanagement.

Rainfall in Johor:Figure shows the monthly rainfall patternin Johor for the period 1971 20012.

Mean Rainfall in Johor 1971 - 2001

0

50

100

150

200

250

Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Month

It is to be noted that monthly rainfall inJohor averaged at 187 mm with a

maximum of around 230 mm occurringduring monsoon periods.

Thus, on a typical rooftop catchmentsarea of 100 sq m, average monthlyincidence of rainfall is estimated at 18.7KL (equivalent to roughly three barrels of

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200 liters each day). This is a significantamount of water sufficient to meet most

of the requirements of a typical Malaysianhousehold.

Benefits of RainwaterHarvesting:

There are many benefits to be derived

from harvesting this bountiful flow ofrainwater on our rooftops.

For the user, the benefits to be derivedare:

Independent and ample supply of

water in the dwelling.

Water received is free of costs.Use of this water significantlyreduces water bills for purchasedwater from municipal supply.

Costs incurred for purifying thewater for potable use are nominal.

For users located in the ruralareas, an independent supply ofwater avoids the cost of installinga public water supply system.

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For the environment, there are manyadvantages as well:

Harvesting rainwater is not onlywater conserving, it is also energyconserving since the energy inputrequired to operate a centralizedwater system designed to treat andpump water over a vast service areais by-passed.

By capturing water directly, we cansignificantly reduce our reliance onwater storage dams. This places lessstress on these water storagefacilities and can potentially reducethe need to expand these dams orbuild new ones. Avoiding having to

build additional dam reservoirsconsequently avoids ecologicaldamage to the area to besubmerged.

Rainwater harvesting lessens localsoil erosion and flooding caused bythe rapid runoff of water from

impervious cover such as pavementsand roofs as some rain is insteadcaptured and stored. A reducedlevel of storm water require smallersized storm water drainage systemsand also helps in reducing soilerosion into the waterways,

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preventing damage to thesurrounding areas.

Secondary use of grey water (wateronce used in showers etc.) furtherreduces the need for processingeffluent water in treatment plantsbefore discharge into thewaterways.

For the Government:

Reduce the burden for newinvestment to build, operate andmaintain additional water supplysystems such as reservoirs, watertreatment plants and distribution

systems necessary to meet the ever-increasing demands for water.

Save on land area committed tostore water in artificial lakes built forthe purpose

Collecting the rain that falls on a buildingto be used nearby is a simple concept.Since the rain harvested in this manner isindependent of any centralized system,this activity promotes self-sufficiency andalso helps to foster an appreciation forthis essential and precious resource.

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Rainwater quality

Water quality is a term used to describethe chemical, physical, and biologicalcharacteristics of water, usually in respectto its suitability for a particular purpose. Although scientific measurements areused to define waters quality, it's not asimple thing to say that "this water is

good," or "this water is bad." After all,water that is perfectly good to wash a carwith may not be good enough to serve asdrinking water. When the average personasks about water quality, he probablywants to know if the water is goodenough to use at home, to play in, to

serve in a restaurant, etc., or if thequality of water is suitable for aquaticplants and animals.

Rainwater has a distinct advantage overother water sources in that it is one ofthe purest sources of water available.

Droplets of rainwater contain mainly thefollowing impurities:

Dissolved oxygen from the air incontact (beneficial to living beings)

Dissolved carbon dioxide from theair (like that in soda water, but toa much lesser content)

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Nitrogen oxides formed by thunder

lightening (imparts very diluteacidity to the water)

Sulfur dioxide gas contained in thecombustion gases from burning offuels on the ground (imparts very

dilute acidity to the water)

However, the impact of thesecontaminants on water purity is negligiblefor most uses. Although the pH of rain isbelow neutral, it is only slightly acidic,and the smallest amount of buffering can

neutralize the acidity. The low totaldissolved salts and minerals levels foundin rainwater allow for minimal addition ofneutralizing chemicals to adjust the pH tonear neutral where necessary.

Upon contact with surfaces such as roofs,

gutters etc., the water may pick upsoluble and insoluble impurities andmicrobial contaminants that it comes incontact with. The amount of impuritiespicked up naturally depends upon thematerial used for the construction of thesurface over which the water runs, andits state of cleanliness. In Malaysia,

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where most roofs are built fromterracotta or ceramic tiles, with a sloping

orientation, and frequent rainfall, theaccumulation of debris is minimal, andwhat there is, is easily washed awayduring the first flush of rain. It isimportant to ensure that this washingaway does take place becausecontaminants such as dried leaves from

trees, bird droppings, settled dust onrooftops need to be excluded. Installingvery simple traps to bypass the initialportion of rainwater ensures that onlyclean water is collected.

With this provision of automatically

separating the first flush of rainwater prior to collection intostorage, rainwater quality almostalways exceeds that of ground orsurface waters since rainwater doesnot come into contact with soil androcks where it may dissolve salts

and minerals. Further, it is notsubject to many of the pollutantsthat often are discharged intosurface waters such as rivers, andwhich can contaminate groundwater.

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It should be noted however thatrainwater quality could be influenced by

the locality where it falls since localizedindustrial emissions will affect its purity.Thus, rainwater falling in non-industrialized areas will probably besuperior to that in cities dominated byheavy industry.

Aesthetic concerns such as color, taste,smell, and hardness comprise thesecondary testing criteria used toevaluate publicly supplied water. Whenassessed according to thesecharacteristics, rainwater proves to be ofbetter quality than well or municipal tap

water. Inorganic impurities such assuspended particles of sand, clay, and siltfound in groundwater contribute to thewaters color and smell.

Rainwater is the softest natural occurringwater available, with a hardness of zero

for all practical purposes. When usedwith detergents for washing purposes, itcan significantly reduce the quantity ofdetergents and soaps needed forcleaning, as compared to typicalmunicipal tap water. Additionally, soapscum and hardness deposits disappear,and the need for a water softener, often

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an expensive requirement for well watersystems, is eliminated. Water heaters and

pipes will be free of deposits caused byhard water and should last longer.

Rainwaters purity also makes it anattractive water source for certainindustries for which pure water is arequirement. This is of particular interest

to industries where pure water isproduced using expensive and energyintensive processes, such as computermicrochip manufacturing, electroniccomponents, pharmaceuticals and certainfood industries. Since rainwater containsalmost no dissolved minerals and salts it

approximates distilled water quality. Forpeople on restricted salt diets, thisrepresents a decisive advantage overother water sources.

Caution: If it is intended to be usedas drinking water, it is advisable to

subject the rainwater to testing by aCertified Test Laboratory to conformto potable water standards.

Water needs of a typicalhousehold

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Water is needed for various purposes.Some of the uses can be considered

essential while some others may fall inthe category of being peripheral innature.

a. Essential Uses:

This category consists of uses for

water that are related to food andhygiene in a household. Theseare:

Toilets flushing typically 7 Lper flush

Floors mopping and washing typically 20 L per room eachtime.

Bathing (personal and pets) typically 10 L per minute in ashower.

Washbasin usage typically 5 -10 L per minute while brushingteeth and shaving etc.

Clothes washing typically 100 150 L per wash cycle.

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Machine dishwashing typically 50 Lper dishwater cycle.

Hand dishwashing typically 5 10 Lper minute under a running water tapin a washbasin.

Cooking (potable)

Drinking (potable)

b. Peripheral Uses:

Gardening typically 10 - 15 L perminute from a gardening hose. 5 10 Lper minute from a sprinkler head

(depending upon size of the sprinklerhead and water pressure).

Washing of cars, motorbikes etc. typically 10 L per minute from a washspray gun.

General outdoor washing

The actual quantity of water usage by ahousehold therefore depends on thenumber of occupants, user habits,number of vehicles maintained,gardening needs, and the physical sizeof the household premises.

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Quantitative potential ofharvesting from the roof tops

For Households: As mentioned earlier,Malaysia receives 2,300 mm of rainfall onthe average, during a year. Based on acatchments area of 100 sq m (typical

rooftop size of an average dwelling) thisamounts to receiving 230 KL of rainwateron a roof in a year.

As noted above, in order to ensure thatonly clean water is collected for use, it isessential to segregate the initial rainfall

that may contain contaminants such asbird droppings, dried leaves, dirt etc. thatwould have collected on the catchmentsarea between rainfalls. Typically 50 L ofthe initial rain falling on a 100 sq. m areaneeds to be discarded. Since rain occursintermittently throughout the year the

number of times roof washings need tobe diverted depends upon the number ofrainy days in a year. While detailedreliable data of rainy days is not available(and varies from year to year),conservatively one may assume thatrainfall occurs over half the number ofdays in a calendar year. Thus an

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estimated amount of 10 KL of rainfallneeds to be discarded annually as

contaminated water before collection ofclean water for domestic use.

Therefore it is reasonable to assume thatapproximately 220 KL of clean rainwatercan be collected from a 100 sq. mcatchments area of domestic rooftop,

providing an average daily supply of 600L (approx three barrels of 200 L)available water for use. For mosthouseholds in Malaysia, this constitutes amajor part of the water consumed. Thebar chart below shows the averagemonthly rainwater that may be collected

from a 100 square meter roof topcatchment area.

Further, since rainfall is an intermittentphenomenon, sufficient storage capacityneeds to be made available to create abuffer and ensure that there is a

continuous supply for use.

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Monthly Estimated Rainwater

Harvested

0

5

10

15

20

25

JanFebMa

rAprMayJu

nJulAuSe

pOctNovDe

cMonth

M3/Month

For Industrial Users: The potential forharvesting rainwater for industrial uses isgreater due to the availability of muchlarger rooftop catchment areas. Inestablishments, using multiple buildings

and sheds, centralized collection tanksshould be considered. Typically, totalcatchment area of 10,000 Sq. M providesa potential rainwater collection of 23,000KL annually. Due to a very low mineralcontent, demineralization of this watermakes it attractive for uses as boiler feed

water, and other applications where softwater is used. Significant savings in costsare envisaged.

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Rainwater Harvesting Method

Rainwater is harvested using aninstallation of pipes and tanks in anarrangement that allows for automaticallydiverting the first flush of rain that iscontaminated with dirt etc deposited on

the catchments area followed bycollection in a storage tank for furtheruse. The installation also includes asystem of supply to water user outlets viapumping or gravity depending upon thearrangement. In certain instances,provisions may also be made for chemical

dosing and water filtration.

Components of anInstallation:

The Installation for rainwater harvestingconsists of the following components.

Catchment Area: Catchment area is thesurface area from which rainwater can becollected as clean water. Usually, thiscomprises the roof over a house, and anyassociated covered portions of thedwelling, including sheds, factory roofsetc. that are situated above ground level.

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Concreted or tiled pathways should notbe included, since these surfaces are

normally heavily contaminated with dirt,oil spills, soil bacteria etc. The size of aroof catchment area is the buildingsfootprint under the roof. The catchmentsurface is limited to the area of roof,which is guttered. A simple method tocalculate the size of a catchment area

would be to multiply the length and thewidth of the guttered area that forms theboundary of the catchment surface.Often, the roof area is divided intoseveral guttered zones. A sum of allthese areas provides the total catchmentarea that is available for rainwater

harvesting.Caution: Rainwater collected fromsurfaces containing lead should notbe considered for any potable use.

Gutters: These are the transport

channels often shaped as half rounds, oras V or U shaped open top channelsthat are placed to collect the water runoff from the catchment area. Gutters arenormally adequately sized to allow flowof all the collected water from thecatchment area during heavy downpourconditions. It is advisable to install wire

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mesh screens over the gutters to avoidclogging of the downspout attached to

the gutters. The outside face of thegutter should be lower than the insideface to encourage drainage away fromthe building wall.

Downspouts: These are vertical orslanting pipes that receive water from the

Gutters and transfer the collected waterinto roof washers. An adequately sizeddownspout should be able to handle allthe rainfall collected from the catchmentarea. Downspouts designed to handle 5cm of rainfall during a 10-minute periodare considered adequate. Downspouts

are typically made of the same materialas the gutters but of a smaller crosssection.

Roof washer: This is a purpose builtcombination of a screen to collect debristhat may have fallen on the catchment

area during dry periods between rainfallsand a stand pipe (or a small container) ofsufficient volumetric capacity to receiveand by-pass the first flow of rain andwash away any dirt, bird droppings etc.that may have collected on it beforecollecting clean rainwater into the storagetank. It is a simple device with no moving

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parts, located at a convenient and easilyaccessible height. It requires occasional

attention to clear away accumulateddebris if there is any. The device consistsof a funnel with a wire mesh screen fittedon it, with a standpipe of 150 to 200 mmdiameter underneath (or a container),that collects the first flush of rainfall.Once it has filled up with the first flush of

water, the rest of the water overflowsinto the downspout connected to thestorage tank. The roof washer is sizedto collect at least 30 liters of waterfor every 100 sq m of catchmentarea. One has the option to either drainaway the water in the roof washer or use

it for any non-potable purpose ratherthan wasting it. One must be extracareful about roof washing, if thecollected rainwater is to be used forhuman consumption.

Specially designed automatic diversion

valves are also used as roof washers todrain away the initial flow of rainfall priorto collection, as an alternative to theabove method. However, these are notcurrently available in local market.

Note: Trimming of any treebranches that overhang the roof is

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strongly recommended since thesebranches are perches for birds and

produce leaves and other debris.

Piping: The connection between thestandpipe and storage tank is a pipe ofsufficient size to allow rapid flow of cleanrainwater into the storage tank. PVC orGalvanized Iron pipes are commonly used

for this purpose.

Storage Tank: A storage tank ofsufficient capacity to receive hold andsupply rainwater forms an important partof the installation. The tank should besized such that it maximizes the

collection of rainwater from the availablecatchment area, and also providessufficient storage capacity to meet thewater needs between refills withrainwater.

For an average household, a Storage

Tank of 1,000 L 2,000 L capacity (tocollect rainfall on 100 sq m catchmentsarea) is considered adequate in view ofthe frequent rainfall pattern in the region.

There are several factors to be taken intoconsideration while selecting a suitable

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location for a tank. Among the importantones are:

Space and aesthetic considerations a tank may be located above or belowground depending upon space available,and harmonizing with the surroundings.If supplementary water were to bereceived occasionally from road tankers,

easy access to the tank for this purposewould be an important consideration.

Hygiene the tank should be placed inlocations away from sources of pollutingsmells such as toilets, animal shelters,septic tanks etc. This is of particular

importance if the water is to be used forpotable purposes. The tank should alsobe easily accessible for inspection,addition of chemicals (when needed) andease of cleaning out when necessary. Atight-fitting cover is essential to preventevaporation, mosquito breeding, and to

keep insects, birds, lizards, frogs androdents from entering the tank. A tanklocated in a shaded area away fromsunlight, helps in keeping the storedwater cool, reducing the incidence ofalgal and bacterial growth in the storedwater.

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Elevated Location a tank located at aheight obviates the need for pumping out

the water for ground level usage such aswashing of cars, gardening etc. However,a pump will be necessary to supply waterto any user points above the level of thetank. A tank filled with 1000 liters ofwater weighs over a ton. Care should betaken to provide supports and foundation

sufficient for the size of the tankinstalled.

Water storage tanks can be either ofprefabricated type or built on site.Prefabricated tanks made of Polythene,PVC, Stainless Steel, Galvanized Iron,

Precast Cement, Fiberglass, are readilyavailable. Tanks may also be built on siteusing reinforced cement concrete ormasonry. Such tanks should be suitablywaterproofed and sealed, to preventcontamination of contained water.

Water Treatment: As mentionedearlier, the rainwater as it falls on thecatchments area is very clean, andcontains minimal impurities. However,once rain comes in contact with thecollection surface, it can wash manytypes of bacteria, molds, algae, protozoaand other contaminants into the collected

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water. Health concerns related tobacteria, such as salmonella, e-coli and

legionella, and to physical contaminants,such as pesticides, lead, and arsenic, arethe primary criteria for drinking waterquality analysis. Falling rain is free ofmost of these hazards. Choice oftreatment depends upon its ultimate use.

If the rainwater is intended for use insidethe household, either for potable usessuch as drinking and cooking or for non-potable uses including showering andtoilet flushing, appropriate filtration anddisinfection practices must be employed.

If the rainwater is to be used outsideforlandscape irrigation, where humanconsumption of the untreated water isless likely, the presence of contaminantsmay not be of major concern and thustreatment requirements can be lessstringent or not required at all.

Rainwater contains almost no dissolvedminerals and salts and is near distilledwater quality. Total dissolved mineralsand salts levels average about 10milligrams per liter (mg/L). TotalDissolved Solids (TDS) can range as highas 50 mg/L and as low as 2.0 mg/L.

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These values are very low whencompared to city tap water, making

rainwater virtually sodium free. The pH ofrainfall would be 7.0 if there werenothing else in the air. However, as rainfalls through the air, it dissolves carbondioxide that is naturally present in the airand becomes slightly acidic. The resultantpH is 5.6; however, any sulfates or

nitrates dissolved from the air will lowerthis number below pH 5.6. Although thepH of rain is below neutral, it is onlyslightly acidic, and the smallest amountof buffering can neutralize the acid. Thelow total dissolved salts and mineralslevels found in rainwater permit even

very small amounts of baking soda (onelevel tablespoon per 500 liters) to adjustthe pH to near neutral. If you plan to useyour harvested rainfall for drinking water,have the water tested by a certifiedlaboratory.

Conveying: Depending upon thelocation of the storage tank and thelevel at which the water is to be used,delivery system for the treatedrainwater may be either by gravity orthrough a pump.

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Typical Household

Installation:

Figure below shows a scheme ofarrangement to provide forpressurized discharge of water usingan automatic operating pump.

Roof Washer

Down pipe

Drain Drain

Level Indicator tube

Low Level Switch

Rain Water Harvesting System

PressureSwitch

Power Supply

Rainwater Supply Pump

Rainwater Storage Tank

Wire Screen

To outdoor use

Indoor Overhead TankFor toilets, Washbasins, Showers etc

From Water Mains

Leaf Screen and Roof washer:This consists of a simple standpipe (typically

a PVC pipe of 150 mm diameter) of sufficientlength (or a container) to accommodate 30 50 liters of water, fitted with a coarse screenon a funnel at the top to trap leaves etc. Ithas a valve at the bottom to drain away thewashings collected into it (alternatively, thedrain valve can be replaced with a weep hole

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for slow self draining). A 50 mm pipebranches from near the top and is connected

to the collection tank to receive overflow ofthe rainwater for collection after the roofwasher is filled up with the initial flow ofrain. The roof washer may be locatedadjacent to the storage tank, to allow forshort piping connection to it.

Cisterns or Storage Tanks: Typically aplastic water tank of 1000 1500 Litercapacity is used. The tank should be locatedat a height of approximately one meterabove the ground for easy discharge ofwater.

Conveying: For transfer of water to indooroverhead tank, an inline water filter must beinstalled. Installing a second inlet connectionbelow the rainwater inlet connection shouldprovide for make up of water from municipalmains. This arrangement ensures receivingof municipal water when the water level in

the indoor tank drops to a level thatautomatically opens the valve connected tomunicipal supply.

A gardening hose suffices for the purpose ofuse of water for garden uses, car washing,and floor washing etc.

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Water Treatment: None or minimaltreatment may be necessary for non-potable

uses of this water. Use of two tablespoonfulof household bleach may be added to a fulltank to avoid growth of algae in the tank.

Use of two heaped tablespoons of bakingsoda (to neutralize acidity) and twotablespoonful of household bleach (for

safeguarding against growth of algae) isrecommended for a 1000 L of watercollected.

It is to be noted, that rainwater mustnot be used for drinking or cooking

purposes unless it has been tested for

potability by authorized testinglaboratory and certified as fit for this

purpose.

Estimated Cost of installing aSystem for a Household:

Breakdown of an estimate for asystem that is adequate for ahousehold to collect and store 1000 Lof rainwater is given below. Actualcost however may vary according tothe particular location and type ofsystem adopted.

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Estimate of Cost for Installing a

Rainwater Harvesting System

ITEM CostRM

Storage tank (1000 L fibreglass)C/w feed funnel & Strainer 600

Water Pump 450Pipes and valves 200Electric connection 75

Total 1,275(Excludes transport and labor cost)

Tips for reducing water usage:

General: Practice routine common sense

leak detection. Periodically zero read water

meter for leaks Replace worn valves, faucet

washers, O rings

In the Bathrooms and toilets: Install ultra-low flush toilets Use water-wise showerheads

that use 10 l per minute

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Use faucets that flow at 5 L perminute.

Minimize running the water tapwhile brushing teeth and shaving

Turn off shower while soapingthe body.

Take shower of approx. tenminutes or less.

Check the toilet tank for leakage

into the toilet bowl. To do this,add food color to a toilet tank.Appearance of color in the toiletbowl shows a continuous leakand wastage of water.

In the kitchen:

Avoid pre-rinsing of dishes beforeloading dishwasher. Soak dishes before hand washing

to remove stubborn deposits. Avoid overloading clothes washing

machine and thus need forrewashing.

Always run full load of clotheswash.

Peel and clean vegetables in abowl of water instead of in runningwater.

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Car washing: Use pressure spray gun for rinsing

the car after soap. Avoid using open-ended hose. Use bucket and sponge for

soaping the car.

Watering the lawns: Use a sprinkler instead of flooding

the lawn with water. Use a cutopen empty sardine can on thelawn to know how much water hasbeen sprinkled.

Water your lawns in the morningor evening to minimizeevaporation loss.

Use hand held shower bucket forwatering the plants, shrubs etc.instead of flooding the beds.

Use a layer of organic mulcharound the plants to reduceevaporation of water.

Careful implementation of these measurescan reduce water consumption by up tothirty percent.

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Acknowledgements:

Some of the information contained inthis Guide has been garnered fromvarious sources on the Internet. Dueto the varied nature of the sources, itis not physically possible to

acknowledge these sourcesindividually.

Professor Dr. R Narayanan, Professorof Civil Engineering, University ofManchester, England, for reading themanuscript and making valuable

suggestions for improvements.

References:1. International Commission on

Irrigation and Drainage, 48 NyayaMarg, Chanakyapuri, New Delhi,India

2. Water Resources Unit, Hydrology& Water Resource Division,Department of Irrigation &Drainage, Malaysia

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BIBLIOGRPHY1. Domestic Roof water Harvesting

Research Programme,Development Technology Unit,School of Engineering, Universityof Warwick, UK.

2. Water Resource Research Center,College of Agriculture and LifeSciences, University of Arizona,

USA.3. Gould, J. E., 1992, Rainwater

Catchment Systems for HouseholdWater Supply, EnvironmentSanitation Reviews No. 32,ENSIC, Asian Institute of Technology,Bangkok, Thailand.

Disclaimer

Readers are advised to ascertain theaccuracy and reliability of theinformation contained in thisdocument independently.

The author(s) and/or distributors ofthis document shall not be heldresponsible for any loss or damagethat may arise directly or indirectlyfrom the use of the informationcontained in this document.

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About the Author:Jitender Dev Sehgal was born in Lahore in undivided India (now inPakistan), and migrated to New Delhi during the partition of the

Country. He obtained a Degree Bachelor of Science with Honours inChemistry from the University of Delhi and a second Degree ofBachelor of Science in Chemical Engineering from the Institute ofTechnology, Banaras Hindu University in India. He went on to therenowned Massachusetts Institute of Technology, Cambridge,

Mass., USA, where he earned a Masters Degree in ChemicalEngineering in 1959. While at MIT, he worked as a Research

Scientist, carrying out research into methods for ultimate disposalof radioactive wastes from nuclear power reactors. Upon return toIndia, he worked as a Research Scientist in the well-known Bhabha

Atomic Research Centre in Mumbai. He then moved to work withUnilever Research Laboratories in India and Europe where over thenext 20 years he developed his career in research in chemicaltechnology development. He relocated to Malaysia in 1979, and hasworked in various managerial positions in the palm oil refining

industry in the country for over 25 years. His interest inenvironment protection, and developing environment friendlymanufacturing processes has continued throughout his working

carrier as a research scientist as well as CEO of various companies.He has played a key role in establishing a unique manufacturing

plant for recycling industrial wastes generated by the palm oilprocessing industry in Malaysia, thus allowing that industry to avoidpolluting the environment. He is currently Managing Director of aMalaysian Company offering innovative technological solutions to

process industrial wastes.

The author has been a committed member of the RotaryInternational since 1980. He is a member of the Rotary Club ofJohor Bahru, and was also a Charter Member of Rotary Club of

Pasir Gudang. He has held various positions in these Clubs, beforebecoming the President of Rotary Club of Johor Bahru 2005 06.

This booklet is the result of his personal and professional interestsand the inspiration given by Carl-Wilhelm Stenhammer, President of

Rotary International 2005 05, who has stressed the importance ofconserving worlds water resources for the future.

The author may be contacted by e-mail: [email protected]

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Rainwater Harvesting Guide for Malaysians

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