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- If you can't access mains (reticulated) water, collecting rainwater from your roof is a good alternative.
- Rainwater is generally safe to drink if it is clear, has little taste or smell and is from a well-maintained system.
- The risk of illness is low for most people. It is higher for people with lower immune response, such as very young children, older people, and people with a chronic illness.
- These people should always boil water used for drinking, cooking and washing food.
How to ensure rainwater is safe?
- To be certain that your water is safe, you may choose to have your water tested.
- Seek advice on collection, timing and the number of water samples from your local council.
- A fee may be charged for this service.
- 'One off' samples can be misleading.
- Install water filters at your kitchen tap.
- Check and maintain the tank and water catchment area twice a year.
How to prevent contamination
- Before installing a rainwater tank, check with suppliers that your roofing material is safe to be used for collecting drinking water.
- Make sure your rainwater tank is correctly installed with screens on all tank inlets and a first flush bypass device.
- If basic maintenance is not kept up, then the quality of your water may degrade and make you sick.
- Basic maintenance is recommended every three or four months.
- Soil and decaying vegetation can accumulate leading to poor odour/taste of your water.
- If there is lots of leaf litter, it may need to be done more regularly.
- Cut back any overhanging branches to minimise leaf litter and reduce wildlife climbing on to your roof.
- Consider bird and animal repelling devices.
- Guttering can be covered with a screen to prevent leaves entering or accumulating in gutters.
Cleaning your roof
- Check for accumulated debris and leaf litter and remove.
- Make sure your first flush device works,
- This will stop a lot of accumulated roof contaminants from going into your tank when it rains.
- Keep the roof in good repair.
- Keep wood heaters in good repair and remove 'Chinese hat' type chimney flue cowls.
Cleaning your tank and tank roof
- The structure should be sound without any holes or gaps that can let animals or birds in.
- If you do find gaps, check for dead animals and look for mosquito larvae then close the access points.
- Also check for any green algal growth.
- Inspect the tank for sediment or sludge every two to three years.
- Cleaned and repair tank inlets, insect proofing and leaf filters to stop contaminants getting in.
How your tank water can get contaminated
Water collected from your roof may get contaminated by:
- chemicals from paint or wood fire smoke from the chimney
- micro-organisms from bird and animal droppings
- decaying leaves that have collected in the gutters
- dead wildlife that falls into the tank.
How to clean your tank
If gross contamination occurs (you find a dead animal in the tank), empty, clean, refill and disinfect your tank with chlorine.
How to disinfect your tank
- Add the correct amount of chlorine to your tank, preferably when it is filling.
- It is important that the chlorine is distributed right through the tank for it to be fully effective.
- Wait at least one hour.
- The water should then be safe to drink.
- You might taste or smell chlorine, but it will quickly disappear.
- These chemicals are available from swimming pool shops and other suppliers.
- Other forms of chlorine such as ‘stabilised chlorine’ should not be used.
- It is recommended to use a solution of 5 milligrams of chlorine for every litre of water.
- For every 1,000 litres of water, this converts to 40 millilitres of sodium hypochlorite solution (12.5 per cent chlorine), or 7 grams of calcium hypochlorite powder (75 per cent chlorine).
- If you don't want to add chlorine to your water, small quantities of water needed for drinking, cooking and washing food can be disinfected by boiling water.
Where to get more information