Rainwater is captured from the roof(s), and brought to a central point, via normal guttering and down-pipes, to enter a storage tank (frequently underground), where it is filtered on entry. A highly efficient and reliable submersible pump delivers the water to a service on demand. Where wished, or a special reason applies, delivery can be to a normal header tank instead.

The size of the storage tank is determined by considering the amount of water available for storage (a function of roof size and local average rainfall), and the amount of water likely to be used (a function of buildings occupancy and function)

Considerations for fitting a rainwater collection system to an existing property

• The external drainage from the roof needs to be modified to bring the water to a central point.
• Access for the tank and excavation is required.
• Internal plumbing is usually required to be seperate out the drinking (incl. bathing) water from the non-drinking water (WC, washing machine & outside tap.