Rainwater Harvesting Systems operate by collecting the rainfall from the roof of a property and storing it in a tank, usually buried in the garden for concealment and to protect from frost.
This rainwater is then either pumped back to the property via a filter and can be used for washing clothes or flushing toilets, or plumbed to supply garden taps for garden uses or car washing.
If the system is designed to provide indoor supplies, a mains water supply is plumbed to top-up the storage tank in the event that it runs dry. The rainwater supplies must be plumbed separately from the mains supply, and due to the alterations required to the plumbing a Rainwater Harvesting System is best installed when building a property, or carrying out significant renovation works.
A property’s suitability for Rainwater Harvesting depends on the occupants’ water consumption and the available roof area.
As a rule of thumb, the following formula will give an idea of the amount of water you may be able to recover using a Rainwater Harvesting System
Roof area (m2) x drainage x filter efficiency x annual rainfall (mm) = Amount you can collect in a year in litres (divide by 1,000 to get cubic metres).
Drainage varies from 0.9 on a steep pitched roof, to 0.4 on a flat roof with gravel. More detail is available from the Environment Agency.
Filter efficiency is generally estimated at 0.9 Annual rainfall averages are available from the Met Office.
Working in conjunction with our sister company, Thomas and Thomas Building Contractors Ltd, Navitas are able to provide a turnkey service to design, install and commission Rainwater Harvesting Systems for domestic applications.
For further information about your property’s suitability for Rainwater Harvesting, please contact us.
A Rainwater Harvesting System can provide up to half of most households water usage depending on available roof area and construction.