With downpipes placed strategically around a home you could collect about 80 per cent of rainwater from the roof area. The Water Corporation suggests that with a roof area of around 100 square metres and our recent average rainfall of around 750mm per year, you can collect over 80,000 litres of water, saving money and being environmentally friendly at the same time.
If you use 125 litres of tank water per day this equates to around 46 cubic metres of water per year, which could be collected on a roof area of only 70 square metres.
Rainwater tanks come in many sizes. For general household use such as flushing toilets, washing cars, watering gardens etc, you would need a tank of around 5,000 litres.
Tanks are available in a variety of materials – galvanised steel, fibreglass (usually more expensive), concrete, galvanised sheet metal or polyethylene. A building permit will be necessary from the local authority before installation and a licenced plumber will need to install the tank.
Remember that regular maintenance is essential to preserve the quality of your water. The tank needs to be protected from foreign materials like leaves, bird droppings and mosquitos. Installation of an inlet strainer is recommended.
With our heavy rains approaching you need to consider tank overflow. You may also need to install a pressure pump to help circulate the water around your home. Finally if your rainwater is to be used to help flush the toilet, a non-return valve or backflow prevention device will be required.
You should look at the Water Corporation website – www.watercorporation.com.au for further information.
Note also that rainwater tanks may become mandatory in WA under proposed new 5* plus regulations.