Water storage tanks
Rainwater collection
'If the 5 million homes connected to mains water around Australia each had a 1,000 litre water tank, 5GL (5 Billion Litres) of water would not have to be taken from the environment every year'
Australians have been collecting rainwater for over a century. In rural areas, many farms are not connected to mains water supply or have adequate bore-water, hence the rainwater tank has become a symbol of outback Australian culture. Local councils and urban water authorities are increasingly encouraging these systems in urban areas, and in some cases offering rebates to customers who use rainwater. In Adelaide, about half of all houses are already using rainwater tanks!
Using rainwater can save large amounts of water. The easiest way is to use it in the garden, which accounts for 35 to 50% of domestic water use. Using rainwater in the garden requires a relatively simple system, and is encouraged by a lot of water authorities.
Further savings can be made when rainwater is used for toilet flushing (about 20% of domestic water use), as well as in the laundry, kitchen and bathroom. It can also be used in pools, and for washing cars. In some situations, (as in some rural areas), it is possible to use rainwater for all domestic uses, and not draw upon the mains supply.
Issues associated with rainwater use
There are some important factors that affect the quality of rainwater, which may also become health issues:
• Contamination from pollutants found in roof and pipe materials.
• Contamination from bird droppings, local pollution, and organic material collected on the roof.
• Breeding of mosquitos in the water supply.
The quality of water you need to maintain will depend on its use. However, water from rooftops that contain harmful chemicals should not be used for any purpose. Obviously, drinking water will have to meet the standards set by health authorities.
These quality issues can be overcome if you use approved products and techniques. Tanks and other equipment must meet the required standards, and state health authorities will approve most reputable manufacturers and installers . Your local water authority should be able to recommend high quality products, and approve your system.
Why use rainwater?
• Using rainwater can reduce your water bills, as rainwater is free. You may be eligible for a rebate on rainwater products from your local water authority.
• Collecting rainwater allows you to be prepared for times of low rainfall, so you can still maintain your garden, especially if there are water restrictions in your area.
• It reduces the load on stormwater systems, as roof runoff is not flushed into the drains.
• Using rainwater reduces the need to build more water storage dams, which may have to be situated in environmentally sensitive areas.
• If your tank is going to be large, consult a builder or engineer, as it may require structural support.
• Have the tank installed by a plumber or the tank manufacturer. This will ensure the system operates efficiently, and is easy to maintain.
• Lead-based paint and flashing, or tar-based coatings found on some roofs effect water quality. Make sure your roof material is non-toxic.
• A u-shaped gutter traps leaves and twigs. If possible, choose water friendly gutters, or cover existing gutters in mesh.
• Try to make all pipes 'dry'. This means having a continuous downward path so water can't accumulate in them between flushes.
• Have all openings covered by a mosquito-proof mesh.
• Install a first flush diverter on the downpipe. This is especially important in areas of high pesticide use or atmospheric pollution.
• A sump box between the downpipe and the tank can slow the water flow down, separating out any sediment no previously diverted.
• Make sure the tank overflow outlet is connected back into the stormwater pipe or irrigation system.
• Make sure tank water is aerated, so it will not become stagnant.
• Clean the inside of the tank every few years, as sediment will accumulate.
• You may need to install a pump to provide adequate water pressure for some appliances. Consider appliances that can operate at less than mains pressure. |
