Rainwater Tanks
Rainwater tanks have supplied rural water needs in Western Australia for many years. The Department of Health supports the use of rainwater tanks for non-drinking water uses. There is some increased risk of pollution by airborne chemical and microbiological contamination when rainwater tanks are used for drinking water purposes.
The amount of water collected by a rainwater tank varies and major determinants include:
- size of roof area;
- indoor and outdoor use or outdoor use only;
- rainfall patterns;
- number of household occupants (and therefore usage); and
- tank size.
Rainwater tanks rely on rainfall, and storage capacity is limited in urban areas by the available space (generally two kilolitres but could be as big as ten kilolitres). They are best used frequently, as this increases the number of times they can be refilled (such as connecting for toilet and clothes washing use).
Perth gets 70% of its rainfall in four months during winter and spring. This means that the tanks may only be filled once or twice if they are only used for outdoor water use in a long, dry summer.
Most local councils require that a building application be approved before a rainwater tank can be installed. The State Government provides a Waterwise Rebate of up to $600 for tanks greater than 2 kilolitres that are plumbed into the house.