Rainwater Harvesting

Code: 
U02
Sector: 
Urban
The complete description of the NWRM: 
Summary: 

Rainwater harvesting involves collecting and storing rainwater at source for subsequent use, for example, using water butts or larger storage tanks. Water butts are the most widely applied and simple rainwater harvesting technique, collecting rainwater runoff from roofs via a connection to the roof down-pipe. They are primarily designed for small scale use such as in household gardens, although a range of non-potable uses is possible.

A limitation of rainwater harvesting as an NWRM is that during wet periods, water butts are often full and water use may be low, resulting in little or no attenuation or reduction in outflow rates or volumes. As a result there are differing opinions about the role of rainwater harvesting in providing a water retention function. Tanks can be specifically designed and managed to accommodate storm water volumes, which is likely to be more effective when applied at a larger scale than individual properties. In general, however, rainwater harvesting should be considered only as a source-control component in a SuDS ‘train’ where, in combination with other measures, they will contribute to effective and sustainable water management.

Illustration(s): 

Rainwater harvesting (USA)

Source: http://www.clemson.edu/sustainableag/rainwater.html

Tank containing rainwater

Source: Andras Kis’ presentation, NWRM Workshop 1

Possible benefits with level: 
Benefits Levelsort descending
ES1 - Water storage High
ES7 - Flood risk reduction Low
PO9 - Take adequate and co-ordinated measures to reduce flood risks Low
BP1 - Store runoff Low
BP2 - Slow runoff Low
PO3 - Improving status of hydromorphology quality elements Low
PO5 - Improving quantitative status Low
ES5 - Climate change adaptation and mitigation Medium
Case study(ies): 
Last updated: 09 Jun 2015 | Top