Stormwater harvesting

Stormwater harvesting or Stormwater reuse is the collection, accumulation, treatment or purification, and storage of stormwater for its eventual reuse. While rainwater harvesting collects precipitation primarily from rooftops, stormwater harvesting deals with collection of runoff from creeks, gullies, ephemeral streams, underground conveyances ( pipes ). It can also include catchment areas from developed surfaces, such as roads or parking lots, or other urban environments such as parks, gardens and playing fields. Water that comes into contact with impervious surfaces, or saturated surfaces incapable of absorbing more water, is termed surface runoff. As the surface runoff travels greater distance over impervious surfaces it often becomes contaminated and collects an increasing amount of pollutants. A main challenge of stormwater harvesting is the removal of pollutants in order to make this water available for reuse. Stormwater harvesting projects often have multiple objectives, such as reducing contaminated runoff to sensitive waters, promoting groundwater recharge, and non-potable applications such as toilet flushing and irrigation. Stormwater harvesting is also practiced in areas of the United States as a way to address rising water demands as population rises. Internationally, Australia is notable in its active pursuit of stormwater harvesting. Ground catchments systems channel water from a prepared catchment area into storage. These systems are often considered in areas where rainwater is scarce and other sources of water are not available. If properly designed, ground catchment systems can collect large quantities of rainwater. In arid ranch land, a catchwater or cattle tank can be constructed across shallow ephemeral washes to impound and collect what little stormwater does generate there. This untreated water is easily accessed and utilized by livestock. More intricate collection and processing systems are necessary for stormwater harvest to be reused for human uses.