Is The Water In Your Rainwater Tank Safe To Drink?

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1 E N V I R O N M E N T A L H E A L T H G U I D E Is The Water In Your Rainwater Tank Safe To Drink? Rainwater from your roof can be a vauabe resource and can be quite safe to drink when stored in a propery instaed and maintained water catchment system. Foow the information in this guide to minimise the risk of disease to you and your famiy. WHAT HAPPENS TO THE WATER IN YOUR TANK? Heavy materias in rainwater sette on the bottom of the tank and form a thick ayer of sudge. Rainwater generay contains few chemicas. However, airborne contaminants in major urban and industria centres may increase poution. Micro-organisms from the roof or gutters can buid up in the sudge ayer. Most micro-organisms are harmess and do not pose a heath risk. However, some organisms commony found in rainwater tanks can cause stomach aches, diarrhoea and simiar aiments and can be quite dangerous for the very young and the very od. Amoebae may aso be found in rainwater which may cause amoebic meningitis if water is forced up the nose. HOW TO REDUCE POLLUTION Roof catchments shoud be kept cean and cear of eaves. Overhanging branches of trees and shrubs shoud be removed. Cover the inet and turn the down pipe to one side so the water from the first good rain rinses down the roof (especiay if newy cad) and gutters then runs to waste. The inet and overfow of the tank shoud be screened with a mesh to prevent birds, animas and insects from gaining access to the water. A we maintained eaf trap wi reduce the amount of organic matter that enters the rainwater tank through the inet. The tank shoud be covered to prevent ight from reaching the water as it wi encourage the growth of bacteria. The cover shoud have a tighty seaed manhoe, to aow access to the tank for ceaning and inspection purposes.

2 Use ony "food grade" pastic pipe and fittings if you intend to drink the water as some pipes are manufactured with ow eves of ead. HOW TO MAINTAIN YOUR TANK Proper maintenance of the tank, catchment system, roof, gutters and inet is essentia to ensure a safe suppy of water. This is best carried out before the rainy season. You shoud: cean the gutters and tank inet every three or four months; and remove the sudge every two to three years (desudging). Gutter ceaning is not compicated but don't tacke it aone; seek the hep of another person to hod the adder, pass any equipment, etc. If overhead wires are too cose for safety, contact the Western Power Corporation for advice. DESLUDGING Desudging wi depend on the tank's design and size. Sma tanks with a 'cone scour' base are easier to cean than fat-bottomed tanks. Both shoud be drained, rinsed with a hose and, if necessary, tited to drain. The most common method of ceaning big fat-bottomed tanks is to get inside with a bucket, shove and broom and dig out the sudge. A second person shoud be present to ensure the safety of the person inside the tank. Cean a big tank eary in the morning or when the area is shaded to avoid heat exhaustion. For ight inside the tank, use a battery antern not a fame or eectric extension. If chemicas are being used for repairs inside, a respirator may be necessary. Your tank coud crack if it dries out. Check the tank suppier to find out if the type you have can safey remain empty for a few weeks. It might be necessary to put tap water in the tank to stop it cracking. If the tank is your ony source of water and, therefore, cannot be desudged reguary, the water shoud be treated chemicay with chorine, and/or boied before consumption. The best arrangement is to have two tanks and cean them out aternatey. CHLORINATION Reguar chorination of your rainwater tank shoud not be necessary. However, if you suspect the water in your tank is contaminated, it shoud be treated by adding swimming poo cacium hypochorite 60-70% or sodium hypochorite 12.5%. The initia dose to treat the contamination shoud be 7 grams of cacium hypochorite or 40mL of sodium hypochorite per 1000 itres of water in the tank at the time of treatment. The water shoud be stirred then eft to stand for at east 24 hours to aow the chorine taste and sme to dissipate.

3 It is aso important that the chorine you use is not stabiised. To maintain a safe water suppy after the initia dosage, 1 gram of cacium hypochorite or 4mL of sodium hypochorite per 1000 itres shoud be added to the rainwater tank weeky and aowed to stand for a minimum of two hours. The water wi be safe to drink provided the chorine sme is not too strong. It is important to mix the chorine in a pastic bucket IN THE OPEN AIR before adding it to the tank. Mix it thoroughy with the tank water. Do not pour water onto chorine. Aways add chorine to water. ASBESTOS Asbestos-reated diseases are mainy caused by breathing very sma air borne fibres into the ungs over a period of time. There is no evidence to suggest such diseases occur from drinking rainwater coected from an asbestos cement roof. VERY IMPORTANT Lead-based paint and fashings must not be used on the roof if it is in the catchment area for a tank which suppies drinking water. To stop mosquito breeding put a cup and a haf of iquid paraffin or ighting kerosene into your tank. This shoud be done at the end of the winter rains and again if the tank overfows. Both wi evaporate over time so check the tank a coupe of times during the summer. Do not use power kerosene as it wi taint the water. Zinc in the gavanising of an iron tank may cause an unpeasant taste. However, the consumption of ow eves of zinc does not pose a heath risk. Fibregass tanks usuay do not taint the rainwater. The inet pipe shoud have a sieve guard to prevent birds or animas getting into the tank. After the annua cean out, the inet shoud be firmy covered unti it is time to reconnect the pipe. SUMMARY 1. Do not aow the first rainwater to enter the tank. 2. Keep gutters and roofs cean and in good repair. 3. Use a eaf trap on the inet. 4. Screen the inet and overfow for insects/animas. 5. Cover and sea the tank to prevent the entry of sunight, dust and animas. 6. Insta a tighty fitting manhoe cover for ceaning and inspection purposes.

4 FURTHER INFORMATION For further information contact an Environmenta Heath Officer at your oca government or Appied Environmenta Heath Environmenta Heath Service PO Box 8172 PERTH BUSINESS CENTRE WA 6849 Teephone: (08) Facsimie: (08)

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