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Australian Capital Territory Rainwater tanks Guidelines for residential properties in Canberra Reprinted June 2006

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Australian Capital Territory

Rainwater tanks

Guidelines for residential properties in Canberra

Reprinted June 2006

Contents

Foreword 3

Commonly asked questions

Whyinstallarainwatertank? 3

HowcanIuserainwater? 4

HowbigatankdoIneed? 4

CanIdisconnectfromtheACTEWwatermains? 4

Whattypeofrainwatertankisbestforme? 5

Howmuchwillitcost? 5

Arethereanyfinancialincentives? 5

WillIpaylessonmywateraccount? 6

WhatworkcanIdowithoutaplumbingorelectricitylicence? 6

Arethereapprovalcosts? 6

Istankwatersafetodrink? 6

ShouldIaddfluoride? 7

ShouldIusekerosenetocontrolmosquitoes? 7

DoIneedtofiltertankwater? 7

Rainwater assembly options

Illustrations 8-�0

Installation requirements

Rainwatertankbases ��

Coversandlids ��

Screensandstrainers ��

Firstflushrainwaterdiverter �2

Plumbingpipesandfittings �2

Lightproofing �2

Pumps �2

2

Top-upfacility �3

Overflow �3

Maintenance and system management

Drinking water safety

Healthconsiderations �4

Disinfection �5

Roofmaterials �5

Leadflashing �5

Paintsandcoatings �5

Regulations

Planningandbuildingapprovals �6

Buildingwithineasementsornearutilityassets �7

Plumbingapprovals �7

Plumbingrequirements �7

Rainwaterplumbingmaterialsandlabelling �8

Proximitytootherservices �9

Backflowprevention �9-20

Contact details 21

References 21

Appendix A 22

3

Foreword

TheACTGovernmentiscommittedtothewiseuseoftheregion’swater.Thestrategyforsustainablewaterresourcemanagement,'Think water, act water',providesaclearvisionandarangeofinitiativesforthesustainableuseofwaterresources.ItsetstargetstoreduceCanberra'spercapitamainswaterconsumptionby�2percentby20�3and25percentby2023.OneproposalistopromotetheuseofrainwatertankstohelpreducethepercapitademandontheACTEWwaternetwork.

ThisRainwaterTankGuidehasbeenpreparedinpartnershipbetweenActewAGL,EnvironmentACT,theACTPlanningandLandAuthorityandACTHealthandprovidesguidanceontheinstallationofrainwatertanksinresidentialproperties.

Commonly asked questions

Why install a rainwater tank?

Rainwatertankscanmakeanimportantcontributiontowardsreducingthedemandourhomesmakeondamstorages.Rainwatertankscanalsohelpslowtheflowofstormwaterfromoururbanenvironmentintolocalcreeksandrivers.Byusingrainwateryoucanalsomakesavingsonyourwateraccount.

Theseguidelineshavebeenpreparedtohelpyouunderstandthekeyissuesthatneedtobestudiedwhenplanningasuccessfultankinstallation.Subjectscoveredinclude:

• howmuchwatertostore,• healthandsafety,• regulationsand• installationrequirements.

AlltheessentialrequirementsofActewAGL,ACTHealth,theACTPlanningandLandAuthorityandEnvironmentACThavebeenincludedtomakeyourinvestigationseasier.

However,whilethisinformationwascorrectatthetimeofprinting,requirementscanchange.Youareadviseditisyourresponsibilitytoensureyouareawareofuptodatelegislationandregulations.Youshouldcontactrelevantagencieslistedonpage2�toensureyouhavethelatestinformation.

4

How can I use rainwater?

Ataponasimplerainwatertankcan:

• supplyirrigationdrippersorasoakerhose,• fillabuckettowashacar,• top-upaswimmingpooland• fillanornamentalpond.

Withadditionalplumbingarainwatertankcansupplywaterto:

• ahose,• irrigationspraysand• aflushingtoilet.

Withcarefulcontrolofwaterqualityarainwatertankcanalsobeusedto:

• fillawashingmachine,• runshowersandbathsand• providesafedrinkingwater.

How big a tank do I need?

Estimatingthesizeofatankrequiresacombinationofexperienceandcalculation.Rainfallisvariableanddemandwillchangewiththeseasonsandtheneedsoftheresident.Inaddition,thesizeoftherainwatertankwilldependon:

• howmuchrainfallseachyear,• theareaofroofavailabletocapturetherain,• howyouplantousetherainwater,• thenumberofpeoplelivinginyourhouse,• thecurrentwaterusagerateand• availablespacetoinstallthetank.

Youcanestimateyouryearlywatersavingswiththecalculatoratwww.thinkwater.act.gov.au/calculators/water_calculators.shtmloratAppendixAofthisbook.Theexperienceofyourlocalrainwatertanksupplierwillalsobeinvaluable.

Can I disconnect from the ACTEW water mains?

Makingyourhomeself-sufficientandindependentfromtheACTEWnetworksupplyrequiresalargecontributingroofareaandsubstantialtankcapacity(probablygreaterthan�00,000litresforanaveragehouse).Canberrahasavariablerainfallandissubjecttodrought,sorigorouswatersavinghabitsarerequiredifyouwantyourhouseholdtobeself-sufficient.Eventhenthereisnoguaranteethatyouwouldneverrunoutofwater.

5

ActewAGLcandisconnectyourmainspressurewatersupplyinaccordancewiththestandardscheduleofprices.Afterdisconnectionyouwillnotbebilledforwaterusagechargesbutyouwillhavetopayanetworkavailabilitycharge,sothereisnofinancialbenefitindisconnecting.Keepingthenetworksupplyforemergenciesortop-upisausefulsafeguard.

What type of rainwater tank is best for me?

Mostresidentialrainwatertanksaremadefromplastic,fibreglass,concrete,corrugatedgalvanisedsteelorcorrugatedsteellinedwithplastic.

Almostanytankmaterialcanbeusedtostorewaterforirrigationortoiletflushing.

Tanksusedfordrinking,foodpreparation,washingclothes,showersorbathingshouldbemadefrom,orlinedwith,adrink-safe(foodgrade)material.

Yourtankmanufacturercanadviseaboutthebestmaterialandmosteconomicalsolutionforaboveorbelowgroundtanks.

How much will it cost?

Rainwatertankpricesvaryaccordingtosize,material,finish,strengthandquality.Itisworthcomparingpricesfromseveralsuppliers.

Otherinstallationcostswillvaryaccordingtothecomplexityofyoursystembutmayinclude:

• transportation,• alterationtoguttersanddownpipes,• tankstandfoundationwork,• afirstflushrainwaterdiverter,• inletandoverflowpipeinsectscreens,• plumbingpipesandfittings,• engagingalicensedplumberforhouseholdplumbing,• watertop-upfacility,• apumptoincreasepressure,andflowratesand• associatedelectricalworks.

Are there any financial incentives?

Financialincentivesintheformofrebatesmaybeavailabletoassistyourpurchaseofarainwatertank.ThedetailsofanycurrentrebateprogramsareavailablefromtheThinkwaterwebsite:www.thinkwater.act.gov.au

6

Will I pay less on my water account?

YoucanexpecttomakesomesavingsonyourActewAGLwateraccountifyouusearainwatertank.However,youmaywishtoestimatewhatthesesavingsarelikelytobebeforeinstallingarainwatersystem.

What work can I do without a plumbing or electricity licence?

Taking due care, a handy person can install:

• tanksandstands,• irrigationsystemsfromadedicatedtank,• apressureboostingpumpusedsolelyforirrigationand• rainwaterguttering,downpipesandstormwaterdrains. A licensed plumber must be engaged to install:

• rainwaterplumbingpipesprovidingwatertothehouse,• pressureboostingpumpsforhouseholdrainwaterplumbingand• tanktop-upsystems(fedfromthecitywatersupply).

Forfurtherdetailseethesectionon‘Regulations’.

A licensed electrician must be engaged to modify or install:

• poweroutletsand• fixedwiringtopumpsorelectricalappliances.

Forfurtherdetailseethesectionon‘Regulations’.

Are there approval costs?

Youmaybesubjecttogovernmentchargesforplanning,buildingandplumbingapprovals.Governmentplumbingchargesmaybeincludedinyourplumber’saccount.DetailsareavailableinthefeesandchargesbookletavailableattheACTPlanningandLandAuthorityCustomerServiceCentre.

Is tankwater safe to drink?

TheuseoftankwaterfordrinkingorfoodpreparationisnotrecommendedwherethereisapotablenetworksupplyavailablewhichmeetstheAustralianDrinkingWaterGuidelines.Ifyouchoosetoinstallarainwatertanktoprovidedrinkingwater,youshouldcontactACTHealthforadviceandfollowthesuggestionsincludedinthesectionon'drinkingwatersafety'.

7

Should I add fluoride?

Rainwaterdoesnotcontainfluoride.Youshouldnotaddfluoridedirectlytotherainwatertank,asitisverydifficulttocontrolthecorrectdosagerate.Talktoyourdentistaboutsubstitutes.

Should I use kerosene to control mosquitoes?

Lowoxygenlevelsintankwater,causedbyexcessivesludge,willattractmosquitoes.Youmayhaveheardthatateaspoonofkerosenepouredontothesurfaceoftank-waterwillstopmosquitoesfrombreeding.Thisistrue,howeverthereisnoneedtousekeroseneasfineinsectscreensorfinemeshscreensproperlyinstalledoninletandoverflowpointswillpreventmosquitoesenteringthetank.Undernocircumstancesshouldkerosenebeusedifthetankisfordrinkingwater.Kerosenemayalsobedamagingtoplasticor‘Aquaplate’coatings.

Do I need to filter tankwater?

Sedimentandorganicmaterialaccumulatesinrainwatertanks.Afilterontheirrigationsystemcanhelppreventsprinklerheadsfrombecomingcloggedwithsludge.

Afiltermaybeinstalledatthekitchensinktoremoveimpuritiesfromdrinkingwater,howevertheunitshouldbemaintainedinaccordancewiththemanufacturer’sinstructionstopreventthefilterbecomingasourceofcontamination.

8

Rainwater assembly options

Thefollowingassemblyoptionsillustratesomebasicrainwatertankandplumbingconfigurations.

Basic tank

Thesimplestinstallationisarainwatertankonastandwithasimpletapoutletforfillingajugorbucket.

Tap with basic irrigation system

Adedicatedabove-groundtankcanrunasoakerhoseoradrippersystem(bygravity)forthegardenorvegetablepatch.

9

Pump connected to irrigation system with sprinklers

Apumpmaybenecessarytoprovidethepressurerequiredforirrigationsprinklersormicro-sprays.Therainwatertankmaybeaboveorbelowtheground.*

Tank connected to toilets, washing machines and diswashers

Toilets,washingmachinesordishwasherscanusetankwater.Apumpisusuallynecessarytoboostpressureandflow.Therainwatertankmaybeaboveorbelowtheground.*

*Undergroundtankscanbeusedforirrigationsprinklersandhouseholdappliancesbutusuallywillneedapumpto

boostpressureandflowrates.

�0

Plumbingconsiderationsincludethefollowing.

Washing machine options

Washingmachinesusuallyhavehotandcoldwaterinlethoses.Thecoldwaterhosecanbeconnectedtoarainwateroutletormovedtothemains-waterifthetankrunsdry.Ifyouchoosetopermanentlyconnectthewashingmachinetoarainwateroutletitmaybenecessarytoinstallamainstop-upvalveatthetanktopreventthetankfromrunningdry.

Dishwasher options

Under-benchdishwashersareusuallyconnectedtothehotwatersupply.Ifthehotinlethoseisconnectedtoacoldrainwateroutlet,cycletimeswillbelonger.Ifadishwasherispermanentlyconnectedtotherainwateroutlet,youmayrequireamainstop-upvalveatthetanktomakesureitdoesnotrundry.

Toilet cistern options

Toiletcisternscanbeconnectedtoadedicatedrainwateroutlet,howeveryoumayneedamainstop-upvalveatthetanktomakesurethetankdoesnotrundry.Itisalsopossibletoconnectacisterntobothmains-waterandtankwateroutlets,providedthecisternhastwocisternvalves(withair-gapbackflowprevention).

Toilet cistern assembly showing rainwater and mains-water connection

��

Installation requirements

Herearesomeessentialsthatneedtobeaddressedwheninstallingarainwatertank:

Rainwater tank bases

Mostmetalorplastictanksmusthaveastandorbasetocarrythecombinedweightofthetankandwater.Mostflat-bottomedtanksarenotabletocarrytheheavyloadofwaterwithoutthesupportofastrong,levelandcontinuousbase.

Whenarainwatertankisfull,everykilolitreofwaterweighs�000kilograms(onetonne)soforsafetyitisimportanttoconstructatankstandthatisstrongandstable.Whenarainwatertankisemptyitcanbeblownoverbystrongwinds,somakesureyourtankisadequatelysecuredtothestand.Lightweightstandsshouldbesecurelyfixedtoaheavyfooting.

Ifyouareintendingtouseapumptodistributethewater,therainwatertankcanbeatalmostanylevel.Ifyouwishtofeedthewaterbygravityitisusuallynecessarytoelevatetherainwatertankonasturdystand.

Topreventexternalcorrosion,theundersideofmetalrainwatertanksshouldbekeptabovethegroundandsitonaself-drainingbase.

Undergroundrainwatertanksmustbesealedagainsttheentryofsurfacerun-off,groundwaterandleakingsanitarydrainsthatmaycontainpesticides,fertiliserandanimal(orhuman)faecalmaterial.

Undergroundtankswillfloatifsurroundedbywater.Makesuretheholeiswelldrained.Seekengineeringadviceifyouareuncertainaboutfoundationorgroundwaterconditions.

Careshouldbetakennottoplacerainwatertanksinsidethedrip-lineofatreecanopy.Rootgrowthcandamagethebaseoftanks.Treesmayfailtothriveifraincannotgettotheroots.

Covers and lids

Arainwatertankshouldhaveanimperviouscovertopreventtheentryofdust,leaves,pollens,debris,vermin,mosquitoes,birds,animalsandinsects.

Itisessentialtosealaccesshatcheswithstrong,close-fitting,childprooflids.

Screens and strainers

Theinlettotherainwatertankshouldincorporateameshscreenorstrainertopreventtheentryofliveinsectsandtocatchleavesandundesirableroofdeposits.Ameshwithopeningssmallerthanonemillimetreisveryeffectiveagainstmosquitoes.

Thetankoverflowshouldalsobeprotectedwithaninsect-proofmesh.

�2

First flush rainwater diverter

Foraddedprotectiona‘firstflush’rainwaterdivertercanbeinstalledtodivertthe‘firstflush’ofrain(containingroofdust,leaves,droppings,etc.)tothestormwaterandthendirectcleanwaterintotherainwatertank.

Fabricated first flush Commercial first flush

Firstflushdiversionvalvescanbefabricatedusingplumbingfittingsorpurchasedasacompletecommercialunit.

Plumbing pipes and fittings

Tankwatertendstobeacidicandcancorrodemetal.Itisadvisable,especiallyinnewinstallations,touse‘rainwater-standard’plasticpipesandfittings.Seethesectionon‘Rainwaterplumbingmaterialsandlabelling’.

Light proofing

Tanks,covers,plumbingpipesandfittingsshouldbelightprooftominimisedaylightpenetrationandalgalgrowthinthewater.

Pumps

Iftherainwatertankcannotbeelevatedsufficientlytogiveadequatepressuretoappliances,itmaybenecessarytoinstallapressure-boostingpump.Thefloatvalvesintoiletcisterns,irrigationsprinklersandthesolenoidvalvesinwashingmachines(ordishwashers)maynotoperateeffectivelywithoutadequatepressure.Thesizeofpumpwillvaryaccordingtotheheightofthetank,heightoftheappliance,diameterofplumbingpipesandtheflowrequirementsofappliances.Theservicesofahydraulicspecialistand/orpumpsuppliermayberequired.

�3

Top-up facility

Iftankwateristhesolesourceofsupplyforselectedtapsorappliances,youmayneedtotop-upthetankfromthedrinkingwaternetworkduringdryperiods.Top-upscanbedonewithahoseorapermanentoverheadfillingtapcomplyingwithACTPlanningandLandAuthorityplumbingregulations.Thetop-upfacilityforrainwatertanksshouldcomplywithAS/NZS3500Part�.

Whentopping-up,remember:

• hosesmustnotbeimmersedinthetankwater(seethesectionon‘backflowprevention’),

• onlytop-upalittle,perhaps�0percent(leavingspacefortherainwhenitcomes)and

• duringwaterrestrictions,topping-upmaybebannedforsomeirrigationsystemsorrequireanexemptionforotheractivities.

Overflow

AlthoughitiscommonpracticeinCanberratoconnectroofdownpipesandtankoverflowstothehouseholdstormwaterdrainagesystem,thereisnoregulatoryrequirementtodoso.Itispermissibletospilltheoverflowontotheyard,howeveritisnotpermissibletoletanyofthatstormwaterrunoutsidetheboundariesofyourproperty.Itisalsoillegaltoconnectthetankoverflowtodischargeintotheseweragenetwork.

Greatcareshouldbetakennottoletstormwaterpondunderfloorsorfloodaroundthefoundationsofbuildings.Highhumiditycanrottimberfloors,corrodemetalfittingsandpromotethecorrosionofreinforcementinconcreteslabs.Anincreaseinfoundationmoisturecontent,especiallyinclaysoils,cancausecrackinginhousewallsorevenoverturnretainingwalls.

�4

Maintenance and system management

Rainwatersystemsneedtobemaintainedregularlytoensurethatthewaterqualityisatitsbestforthepurposeyouintend.Tomaintainyourrainwatertankyoushouldensurethat:

• allthecomponentsarekeptingoodrepairandfreeofcorrosion,

• guttersarecleanedregularlytoremoveleaves,debrisandanimaldroppings(gutterguardscanhelpreducethebuild-upofleavesbutrequireregularchecking),

• rainwaterisnotpondinginroofgutters,

• therainwatertank’sinletandoverflowscreensarecheckedandcleanedregularly,

• the‘firstflush’waterdiverteriscleanedandflushedperiodically,

• therainwatertankisdesludgedifthebuild-upiscloggingfiltersorcolouringthewater,

• therainwatertankroofisfreeofcorrosionand

• theaccesshatchissecure.

Drinking water safety

Health considerations

Inurbanareasaccesstoareticulatedpotablewatersupplyremainsthemostsafeandreliablesourceofdrinkingwaterforthecommunity.Theuseofarainwatertankfordrinkingpurposesisnotrecommendedwhereareticulatedsupplyisavailable.Inurbanareasairbornecontaminantsandotherpollutantsmayfindtheirwayintorainwatertanks.

Ifyouchoosetouserainwaterfordrinking,foodpreparationorpersonalhygiene,itisimportanttominimisetheriskofcontamination.Pleasetakethefollowingprecautions:

• screenallopeningstopreventleaves,insects,birds,possums,frogs,faecesandotherforeignmaterialfromgettingintothetank,

• therooffinish,gutters,down-pipes,tankandplumbingsystemmustbemade‘drinkingwatersafe’—ifindoubtgetaclearancefromtheproduct/paintmanufacturer,

• installa‘firstflush’devicetodivertthefirstflushofdirtyroofwaterawayfromthetank,

• flushstagnantmainsorrainwaterfrommainsorrainwaterplumingpipesiftheyhavebeenunusedforalongtime,

• donotletcontaminatedgroundwaterinfliltrateundergroundwatertanks,

• checkandmaintainthesystemregularly,and

• contactACTHealthifyouhaveanyhealthconcerns.

�5

Disinfection

Regulardisinfectionofrainwaterheldindomestictanksisnotconsiderednecessaryinmostcasesandisgenerallyonlyrecommendedasaremedialaction.

Asthemicrobiologicalqualityofthewaterattimesmaynotbeasgoodasreticulatedwatersupplies,peoplesuchastheveryyoungorelderly,orimmuno-compromisedshouldconsiderboilingthewaterbeforeconsumptionorforuseinfoodpreparation.Heatingandholdingtherainwateratarollingboilforoneminuteormorewillkillanyharmfulmicroorganisms.

ChlorinationiseffectiveagainstharmfulbacteriaandmanyvirusesbuthaslimitedeffectsagainstprotozoasuchasGiardia andCryptosporidium.Itshouldbenotedthattheeffectivenessofchlorineisshortlivedanditwillonlyactonwhatisinthetankatthetimeofdosing.

Iftherainwaterissuspectedasbeingapossiblecauseofgastricillness,thentherainwatertankandcatchmentareashouldbeinspectedandappropriateremedialactiontaken.

Roof materials

Roofsconstructedofcementorterracottatiles,Colorbond®,galvanisedsteel,Zincalume®,fibrouscement,polycarbonate,fibreglassorslateshouldbesuitableforthecollectionofdrinkingwater.Ifindoubtgetaclearancefromthemanufacturer.

Steelcladdingsshouldbefreeofcorrosion.

Lead flashing

Asaprecautionleadflashingshouldnotbeonthosepartsoftheroofusedasadrinkingwatercatchmentarea.Inthecaseofanexistingroof,leadflashingshouldbereplacedifpossible,althoughitmaybepossibletocoattheflashingwithsuitableroofpaint.Askyourpaintsupplierforadvice.

Paints and coatings

Beforepurchasingmaterialorpaintforroofsusedtocollectdrinkingwater,readandobservethemanufacturer’srecommendations.

�6

Regulations

ThissectionsetsoutACTPlanningandLandAuthorityandActewAGLrequirementsfortheinstallationofrainwatertanks.

Planning and building approvals

TheACTPlanningandLandAuthorityrequiresthelocation,sizeandinstallationofrainwatertankstobeappropriatetothestreetscapecharacterandnottoimpactontheamenityofresidents.

Iftherainwatertankisforwardofthefrontbuildinglineitisusuallyrequired:

• tohaveaminimumsetbackfromthefrontboundarynotlessthan50%oftheminimumsetbackapplicabletothatproperty,

• nottoreduceviewstothestreetfromwindows,

• nottoreducesolaraccessordaylighttohabitablerooms,and

• tobescreenedinasensitivemannerwithappropriateshrubberyorwalling.

ResidentialsetbacksarepublishedinPlanD2.�ofAppendix���.�(ResidentialDesign&SitingCodeforSingleDwellingintheACT)orAppendix���.2(ResidentialDesign&SitingCodeforMulti-DwellingintheACT).

Theinstallationofarainwatertankrequiresplanningapproval(andperhapsbuildingapproval)ifitis:

• infrontoftheresidence,

• morethan�7,000litrescapacity,

• locatedinaheritagelistedarea,

• higherthan2.4metresabovenaturalgroundleveland

• madeofreflective,whiteoroff-whitematerial.

Inaddition,ifthetankistobeinstalledwithin3metresoftherearboundaryand/or�.5metresofasideboundary,planningapprovalmustbesoughtifthereisanotherclass�0structureontheboundary.(Class�0structuresincludepoolsandwatertanks.)

Fordesignandsitingadviceinaheritagearea,[email protected].

TheACTPlanningandLandAuthoritywilltellyouifitisalsonecessarytoobtainbuildingapprovalfromaprivatecertifier.

�7

Building within easements or near utility assets

Rainwatertankscannotbeconstructedwithineasementsorwithinthe‘protectionenvelope’requiredforutilityservicesdescribedinRule2ofActewAGL’s‘BuildingoverornearACTEWCorporationwaterandsewerpipes’brochure.PermissibledistancesbetweentanksandoverheadelectricitymainsaresetoutinSection�9ofthe‘UtilityNetworks(PublicSafety)Regulations’,andvaryfrombetween0.�metreto4metres,dependingonthevoltageoftheaerialcableconductor.Thelocationofnaturalgas,stormwaterandcommunicationassetscanbeobtainedbyphoning‘Dial-Before-You-Dig’on��00.

Plumbing approvals

Theinstallationofarainwatertankdoesnotrequireplumbingapprovalifthetankis:

• freestanding,

• tobeusedonlyforgardenorlawnirrigationand

• notdeliveringrainwatertotaps,fixturesorappliancesinthehouse.

AllotherinstallationsrequireplumbingapprovalandcompliancewithAS/NZS3500Section�4Installation of water supply systems from rainwater tanks.

Plumbing requirements

BelowisasummaryofAS/NZS3500Section�4requirementsforinstallingarainwatertankonaresidentialproperty.

�) Allplumbedpipingsystemsdeliveringrainwatertotaps,fixturesorappliancesinthehousemustbeinstalledbyalicensedplumberandmeettherequirementsofACTplumbinglegislationandAS/NZS3500.

2) AsageneralruletheremustbenodirectconnectionbetweenarainwatertankplumbingsystemandpotablewaterplumbingpipesservedbyActewAGL’sreticulateddrinkingwaternetwork(inspecialcasesinterconnectionmaybepermittediftheriskislowandadditionalfailsafeengineeringcontrolsareevaluatedandapprovedbytheACTPlanningandLandAuthorityandActewAGL).

3) Whereahigherriskofcontaminationofthewatersupplyisidentifiedtheplumbingregulator,theACTPlanningandLandAuthority,orActewAGLmayrequirethepropertyownertoinstallahigherhazardbackflowpreventiondeviceatthepropertyowner’scost.Generalrequirementscanbefoundlaterinthisbrochureunder‘BackflowPrevention’.

4) Rainwaterplumbingworkservinginternaltaps,fixturesorappliances,mustbenotifiedtotheACTPlanningandLandAuthorityusinga‘StartofWork'noticebeforeworkistocommence.

5) Atop-upfacility(drawingwaterfromtheACTEWnetwork)requiresa‘StartofWork'notice.

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6) Theplumbermustarrangeforalldrinking-waterandrainwaterplumbingworktobeinspectedbytheACTPlanningandLandAuthority.

7) TheplumbermustsubmitaCertificateofCompliancetotheACTPlanningandLandAuthorityandthecustomeratcompletionofthework.

Rainwater plumbing materials and labelling

Plumbingforarainwatersystemmustuseapprovedmaterialsandbelabelledtodistinguishitfromplumbingusedfor(ACTEW)drinkingwater.AllpipesthatmaybeincontactwithrainwatershouldcomplywithAS/NZS4020.

MaterialsusedinplumbingforarainwatertankmustcomplywithAS/NZS3500‘Water supply – Acceptable Solutions’- Section 2 ‘Materials and Products’.Complyingproductsaremarkedwiththe‘AustralianStandardMark’“5ticks”,“W”forthewatermarkor“T”fortypetested.

Allabovegroundrainwaterservicepipesmustbeclearlymarkedatintervalsnotexceeding�metrewiththecontrastingcolouredwording‘RAINWATER’.Wateroutletsshallbeidentifiedas‘RAINWATER’withalabelorarainwatertapidentifiedbyagreencolouredindicatorwiththeletters‘RW’.Thispipelabellingcanbeachievedforabovegroundpipesbyusingadhesivepipemarkers(inaccordancewithAS/NZS�345).

Allbelowgroundrainwaterservicepipesmustbeclearlylabelled‘rainwater’continuouslyalongtheirlength,‘RAINWATER’identificationtapeforbelowgroundpipesshouldbe75millimetreswideandbeinstalledonthetopoftherainwaterpipeline,runninglongitudinallyandfastenedtothepipeatintervalsofnotmorethan3metres.Thiscanbedoneforbelowgroundpipesbyusingidentificationtape(madeinaccordancewithAS/NZS2648).

Rainwater labels

�9

Everyrainwatertankoutletmustbelabelled‘Rainwater’onapermanentsign.

Proximity to other services

RainwaterpipesmustnotbeinstalledinsidethepipeprotectionenvelopeofanyACTEWwaterorseweragemainorActewAGLelectricitymains.Allabovegroundrainwaterpipesmustbelocated�00millimetresfromanydrinkingwaterservice.Allbelowgroundrainwaterpipesmustbelocated300millimetresfromanydrinkingwaterservice.

Backflow prevention

Wherethereisthepotentialforthereverseflowofpollutedwatertocontaminateadrinkingwatersupply,anapprovedbackflowpreventiondevicemustbeinstalled.

Standards

AS/NZS3500PlumbingandDrainagePart�Waterservicessection�4“Installation of Water Supply Systems from Rainwater Tanks”Table�4.�,setouttheminimumrequirementsfortheinstallationofbackflowpreventiondevicesforzoneprotectionforburied,partlyburiedandabovegroundrainwatertanksinresidentialandcommercialapplications.

Table�onpage20suppliesasummaryofbackflowprotectionrequirementsforzoneandcontainmentprotection.

20

Type of installation Hazard ratingAS/NZS 3500

Containment protection at the

property boundary(Watermeter)

Individual or Zone protection at the

tank top up

Residential

Integrated plumbing (externalandinternal)

Underground(fullyburiedtank)

Medium Testabledevice Testabledeviceorairgap

Underground(partlyburied)

Low Non-testabledeviceor

Water meter with integral backflow

prevention*

Non-testabledeviceorairgap

Abovegroundtank Low Non-testabledeviceor

Water meter with integral backflow

prevention*

Non-testabledeviceorairgap

Residential

External rainwater plumbing only

Aboveorbelowground

Externalhosetapsandirrigationonly.

Noconnectiontothenetworkutilityoperator

watersupply

Low Non-testabledeviceor

Water meter with integral backflow

prevention*

Notapplicable

Commercial Application

(externalandinternal)

Aboveorbelowgroundrainwatertanks

Medium Testabledevice Testabledevice

Table 1

* ActewAGL approved water meters.

2�

Contact details

ACT Planning and Land Authority

Development(designandsiting)enquiries�6ChallisStreet,DicksonTelephone-6207�93� 8.30amto4.30pmweekdays

Buildingandplumbingenquiries�6ChallisStreet,DicksonTelephone-6207626� 8.30amto4.30pmweekdaysorCnrLysaghtandHoskinsStreets,MitchellTelephone-62076262 8.30amto4.30pmweekdayswww.actpla.act.gov.au

Environment ACTMacarthurHouse�2WattleStreet,LynehamTelephone-62079777 8.30amto5pmweekdayswww.environment.act.gov.au

ACT Health HealthProtectionServiceTelephone-6205�700 8.30amto4.30pmweekdayswww.health.act.gov.au

Heritage ACT MacarthurHouse�2WattleStreet,LynehamTelephone–62079777 8.30amto5.00pmweekdaysEmail:[email protected]

ActewAGL Water Division�2HoskinsStreet,MitchellTelephone-62483555 8:30to5:00pmweekdayswww.actewagl.com.au

Dial-Before-You-DigTelephone��008.00amto5.00pm

References

NationalEnvironmentalHealthForum,‘Guidance on the use of rainwater tanks’.

NationalEnvironmentalHealthForumMonographs,WaterseriesNo3�998,DavidACunliffe.www.health.nsw.gov.au/public-health/ehd/water/rainwater.html

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Appendix A – Determining rainwater tank size

Thechartsandtablesinthisappendixwillassistyoutochoosethesizeofrainwatertankbestsuitedtoyourneeds.TheyfactorinCanberra’srainfall,youravailableroofareaandtypicalquantitiesusedforgardenwatering,laundryuseandtoiletflushing.

Thefollowingprinciplesapplywhencalculatingthebesttanksizeforyou:

• Thelargertheroofareaconnectedtothetank,themorewatercollected. Forexample,atankconnectedtoonedownpipeonahousewithfourdownpipes canonlycaptureapproximately25%oftherainthatfallsontheroof.

Alldownpipesshouldbeconnectedtogetthemaximumbenefit.

• Themoreusesmadeofyourtankwater,thegreaterquantityofwateravailableovertime.Forexample,ifyouonlyusetankwateronthegarden,verylittlewillbeusedinthecoldermonths,sothetankislikelytofillandoverflow.Year-roundtoiletflushingorlaunderingreducesthelikelihoodofoverflowlossesandincreasesthetotalamountofwateryouwillcollect.

• Canberra’srainfallvaries,withlongdroughtperiods,sotheamountofwater collectedwillvaryfromyeartoyear.Evenverylargetankscanrundry.

Thecharts(onpages25-27)showtheaverageamountofwaterinkilolitres(kl)youcanexpecttobeabletouseeachyearfromatank.Thiswillvaryfromyeartoyearandhouseholdtohousehold.ThechartsarebasedonwaterconsumptionforanaverageCanberradetachedhouse(showninTable�).

Table 1. Average Consumption per Household

WaterUse Amount(kl/year) %ofTotalUse

Gardenwatering&otheroutdooruse �4� 43%

Toiletflushing 60 �8%

Laundry 43 �3%

Otherinternaluses(kitchen,shower,bath,etc.) 86 26%

Total 330 �00%

Comparethesefigureswithyourwateraccountsforthelastfewyearstogetabetterideaofyourownwaterconsumption.

Thefollowingexamplesshowhowtousethechartstodecidewhatsizetankwillgiveyouthebestreturnonyourinvestment.Ifyouhavedifficultyunderstandingtheseexamples,oryouwanttoexamineotheroptions,pleasetalktoActewAGL,theACTPlanningandLandAuthority,EnvironmentACT,oraskyourlocaltankmanufacturerforadvice.

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Example 1

“Myroofis200squaremetres(sqm)andhasfourdownpipeseachdrainingonequarteroftheroof.WhatsizetankshouldIinstallandhowmuchofmyroofshouldIconnecttothetankforgardenwatering,toiletflushingandawashingmachine?”

Step�.OnChart5-Gardenwatering,toiletflushingandwashingmachine(page27)selecttheverticallineforthedifferentroofareas(forexample,fourdownpipes=200sqm).Markwhereitcrosseseach‘tanksize’curve.Readtheavailablewaterfromtheverticalaxis.Recordthesenumbersintoatable,forexample,table2below.

Table 2. Water Available (from Chart 5)

Tanksize(litres)

Wateravailablefromtankinkilolitresperyear

�downpipe 2downpipes 3downpipes 4downpipes

Roofarea:50sqm

Roofarea:�00sqm

Roofarea:�50sqm

Roofarea:200sqm

500 25 4� 48 55

�,000 30 47 57 65

2,000 30 52 68 79

5,000 30 59 82 100

�0,000 30 6� 89 ��0

20,000 30 6� 9� 120

30,000 30 6� 92 �2�

Thetableshowsthatincreasingtheroofareaconnectedtothetanksignificantlyincreases

theamountofwateravailable,particularlyforlargertanks.However,increasingthetank

sizemorethan�,000litresfor50sqmofroofwillnotyieldanymorewater.Alargertank

connectedtojustonedownpipewouldbeineffective.Forroofareasof�00to200sqm,

installingatankgreaterthan5,000litreswouldhavelimitedbenefits.

Forexample,atankof5,000litresfor200sqmprovides�00klperyear.Doublingthe

tanksizeonlyincreasesthisto��0klperyear.

Step2.UsingTable�workouttheexpectedannualaveragewaterconsumptionforyour

householdforthepurposesof‘gardenwatering’,‘toiletflushing’and‘laundry’.

[Toiletflushingandlaundryarethesimplestinternalusestoconnecttoatank.]The

expectedconsumptionfortheseusesis244klperyear.

Step3.Comparetheexpectedannualconsumptionof244klagainsttheexpectedavailability

figuresinTable2.Thendecidehowmuchrainwateryouwanttocollecteachyear.

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Forexample,fromthefiguresinTable2,itcanbeseenthat:

• A�,000litretankconnectedtoonedownpipewillprovide30klperyear;• A5,000litretankconnectedtotwodownpipeswillprovide59klperyear;• A5,000litretankconnectedtothreedownpipeswillprovide82klperyear;• A5,000litretankconnectedtofourdownpipeswillprovide�00klperyear;• A20,000litretankconnectedtofourdownpipeswillprovide�20klperyear.

Rememberthatissuesofcost,space,appearanceandregulationsalsoneedconsiderationbeforeyouselectyourtanksize.

Thecalculationsshowthatthemostyoucancapturefroma200sqmroofisabout50%ofyourexpectedannualconsumptionfortheselecteduses.Anevenlargertank(say50,000litres,oreven�00,000litres)willnotcollectmuchmorewater.

Example 2

“Myroofareais�50sqm.IwanttoknowwhatsizetankIcouldinstallforarangeofuses.”

Step�.UsingCharts�to5,theaveragewateravailablefroma�50sqmroofcanbedeterminedfordifferenttanksizesandpurposes.(SeeExample�forinstructions).Recordthesenumbersinatable.(SeeTable3below).

Table 3. Summary of water available from a 150 sq m roof for a combination of uses.

Wateravailablefromtank(klperyear)

Tanksize

(litres)

Toiletflushing

fromChart�

Toilet&laundry

fromChart2

Gardenwatering

fromChart3

Garden&toiletflushing

fromChart4

Garden,toiletflushing&laundry

fromChart5

500 29 36 32 45 49

�,000 37 45 40 52 58

2,000 45 57 48 63 68

5,000 53 70 60 78 82

�0,000 58 79 70 87 88

20,000 85 78 90 90

30,000 88 85 9� 90

Thetableshowsmorewaterwillbeavailablegenerallyifthetankwaterisusedregularlyforarangeofpurposes.Thelargertanksarenotasefficientastheyarealreadycapturingmostofthewaterthatcanbecollectedfromaroofof�50sqm.Step2.UsingTable�,workouttheaveragewaterconsumptionfordifferentpurposes.Recordthesenumbersinatable.(SeeTable4nextpage).

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Table 4. Expected demand

Expecteddemand(fromTable�)inklperyear

Toiletflushing Toilet&laundry

Gardenwatering

Garden&toilet Garden,toilet&laundry

60 (60+43)�03

�4� (�4�+60)20�

(�4�+60+43)244

Step3.ComparetheexpectedannualconsumptionsinTable4withtheusablewaterinTable3.Noneofthetanksizeswillsatisfyalltheanticipateddemandfroma�50sqmroof,butwillstillmakeareasonablecombination.Alargerroofareawillprovidemorerainwater,however,issuesofcostsavings,installationcosts,space,appearanceandregulationswillhavetobeconsideredbeforeyoumakeafinaldecisiononwhichistheoptimumtanksize.

Contributing roof area (sq m)

Tank usage: toilet flushing

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Contributing roof area (sq m)

Contributing roof area (sq m)

Tank usage: toilet flushing and laundering

Tank usage: garden watering

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Contributing roof area (sq m)

Contributing roof area (sq m)

Tank usage: garden watering, toilet flushing and laundering

Tank usage: garden watering and toilet flushing

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