Rain gardens are a form of stormwater management using water capture. Rain gardens are shallow depressed areas in the landscape, planted with shrubs and plants that are used to collect rainwater from roofs or pavement and allows for the stormwater to slowly infiltrate into the ground.
Ubiquitous lawn grass is not a solution for controlling runoff, so an alternative is required to reduce urban and suburban first flush (highly toxic) runoff and to slow the water down for infiltration. In residential applications, water runoff can be reduced by 30% with the use of rain gardens in the homeowner’s yard. A minimum size of 150 sq. ft. up to a range of 300 sq. ft. is the usual size considered for a private property residence. The cost per square foot is about $5–$25, depending on the type of plants you use and the slope of the property. Native trees, shrubs, and herbaceous perennials of the wetland and riparian zones being the most useful for runoff detoxification.