Water is a valuable resource and rainwater stored in a tank is safe to drink as long as proper steps are taken. You just need to ensure that parts of your rainwater harvesting system are made of safe food-grade materials and properly maintained.
To ensure the safety of your catchment area, you need to consider:
- rainwater tank – whether your tank is made from food-grade material
- roofing and pipework – what material your roof and pipework is made from
- contaminants – can leaves, debris, animal droppings, bacteria and parasites enter you water supply?
Water Tank Materials
Most rainwater tanks manufactured in Australia are suitable for storing drinkable rainwater. To be sure, you should look for compliance with the Australian Standard AS/NZS 4020 – ‘Testing of products for use in contact with drinking water’.
Drinkable rainwater can be collected from most roof types. You should however avoid roofs with lead flashings, covered with lead-based paints, bitumen and tar or treated timbers. Roofs with these properties will contaminate your water supply.
If you roof is newly installed or freshly painted, then it is best to wash it down and discard the first few runoffs of rainwater if using your tank water for drinking purposes or in cooking.
Reducing Rainwater Contaminants
Contamination can happen from a number of things:
- Animal droppings (e.g. from birds, bats, possums, etc.)
- Mosquitoes and frogs getting into your rainwater supply
- Bacteria, parasites and microorganisms
- Chemical spraying in your area
- Air pollution from nearby industries like manufacturing plans, spray painters, chemical plants and quarries or vehicles associated with freeways and main roads.
You can maintain high water quality by screening your gutter, and using water tank accessories such as leaf eaters, water strainers, rainwater diverters and even tank self-cleaning systems.
Rainwater maintenance steps you can take include:
- pruning tree branches hanging over your roof or tank
- cleaning your roof, gutters and leaf strainers every couple of months
- routinely inspecting your water tank’s screens, water diverter and inside your tank.
Add Water Filtration with Chlorination
Sometimes, despite best efforts, undesirable (even life threatening) organisms can find their way into your water source.
For example, a rare parasite called Naegleria Fowleri (a “brain eating” parasite) thrives in warm water and can survive in springs, lakes, ponds and also quite possibly in water tanks. While rare, several children in rural Queensland recently died from this parasite after exposure to untreated water.
So ensuring your water supply is properly chlorinated, whether used for drinking, washing or in your garden will provide safety against harmful contaminants in your water supply.