Rainwater Harvesting
An important aspect of green building and sustainable design is human interaction with the hydrologic cycle. Urban environments have reduced areas covered by vegetation, and increased impervious surfaces such as pavements, roads, and rooftops. Historically, stormwater runoff has been viewed as a waste product and a nuisance. In sustainable design, stormwater runoff is viewed as an opportunity and a resource. The use of harvested rainwater for lanscape irrigation can significantly reduce domestic potable water consumption. Managing building runoff on site means removal of a substantial amount of stormwater from wastewater systems, reducing sewer overflow events. Furthermore, the combined practices of rainwater harvesting and conversion of impervious surfaces to planted ones (green roofs, curbside plantings, parks) and pervious hardscapes can mitigate the degradation of receiving waterways (and associated wildlife) from urbanization.
The basic components of rainwater harvesting systems for irrigation include:
catchment (rooftops and or paved areas), conveyance (gutters and downspouts),
storage (above or below-ground tanks), and distribution (hose or pump and drip
irrigation system).
A Residential System with an Above-Ground Tank:
Example Scenario: 500 SF Landscaped Area with 500 SF Catchment Area in Coastal San Diego County Month Total irrigation Available runoff Excess runoff Accumulative Irrigation required Irrigation requirements for supply to storage storage from storage required established plants municipal Jan 112 701 589 589 0 0 Feb 112 645 533 1122 0 0 March 224 701 477 1599 0 0 April 337 252 0 1514 85 0 May 337 84 0 1261 253 0 June 449 28 0 840 421 0 July 449 28 0 419 421 0 August 337 28 0 110 309 0 Sept 337 84 0 0 110 143 Oct 224 140 0 0 (empty) 84 Nov 112 337 225 225 0 0 Dec 56 393 337 562 0 0 Annual 3086 3421 335 897 0 0
More Information About Rainwater Tanks
Rainwater Collection Benefits and Resources
