Rainwater tank
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   Some of the rainwater tanks around CERES Community Environment Park, in Melbourne, Australia. |
Rainwater tanks are installed to make use of rain water, reduce mains water use, and aid self-sufficiency. Tanks can also be used for detention of storm water. However, the initial upfront cost may be discouraging, especially where water charges are otherwise fixed. Also discouraging may be the maintenance required, or the health risks if maintenance is not carried out.
If water is used for drinking, it is usually filtered first. Filters may remove pathogens which may be present in rainwater (such as cryptosporidium and giardia), or for chemical contamination in some areas. While rain water does not contain chlorine, contamination from airborne pollutants may be a risk in urban areas. Many water suppliers and health authorities in Australia, such as the New South Wales Department of Health, do not advise using rainwater for drinking when there is an alternative mains water supply available. However, reports of illness associated with rainwater tanks are relatively infrequent, and public health studies in South Australia (the state with the highest rainwater usage rate) have not identified a correlation. Rainwater is generally regarded as fit to drink if it smells, tastes and looks fine.
Rainwater tanks are constructed from materials such as plastic (polyethylene), concrete, and galvanized steel, as well as fibreglass which is rust and chemical-resistant. Tanks are usually installed above ground, and are usually opaque to prevent the exposure of stored water to sunlight, to avoid algal blooms. Tanks are also covered and screened to exclude insects, debris, animals and bird droppings. Tanks often come with a plastic inner lining to both increase the life of the tank and protect the water quality.
Sizes typically range from around 400 litre (105 gallon) capacity to 100,000 litres (26,420 gallons). Larger tanks are commonly used where there is no access to a centralised water supply. Also affecting tank size is predicted rainfall and rainfall variability; the higher prices for larger tanks; intended use of rainwater and typical consumption for these uses; the area of roof draining into the tank; security of supply desired.
Maintenance includes desludging, checking roofs and gutters for vegetation and debris, maintaining screens around the tank, and occasionally removing sediment by draining and cleaning the tank.
See also
External links and references
- [Rainwater, Fact Sheet], greenhouse.gov.au
- [Rainwater tanks], Choice consumer guide
- [Rainwater Tanks] (PDF), NSW Health
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