Stormwater management is a practice that has become more common in recent years as a result of both its environmental benefits and new regulations put into place by local agencies that mandate both the treatment and attenuation of stormwater.
A highly developed built environment, in an urban area, for example, impedes the natural methods that the earth uses to collect and clean rainwater as part of the water cycle. Normally, water accumulates in low lying areas and drains slowly into the soil, where it is cleansed by natural processes and slowly makes its way to underground aquifers. Urban areas are for the most part impermeable, which results in large amounts of runoff that contribute to erosion and deposit harmful sediment and toxins into rivers and other large bodies of water.
Stormwater management is used to prevent these negative effects on the environment. As opposed to letting run off the built environment and accumulate in storm drains and rivers, storage techniques are implemented to capture stormwater for treatment and attenuation. Treatment involves cleaning the water to remove total suspended solids, and attenuation involves letting water accumulate in storage and then slowly releasing it back into the environment, which prevents runoff.
Storage tanks are one of the methods used to attenuate stormwater. Collected stormwater is also often retained for use on the property itself, and new regulations are increasing the frequency of this practice. The water can be used for a variety of purposes such as greywater for plumbing or irrigation for green roofs. Overall, the main goal of stormwater management is to keep as much water on the property as possible to minimize the harmful effects of runoff.