Rain garden

Rain gardens are landscape features that receive rainwater from sources such as roof downspouts, driveways or walkways. The shallow basin temporarily holds the incoming water, which then infiltrates into the soil and is taken up by plants or drains onward. Unlike a pond or wetland, a typical rain garden is designed to drain after a storm rather than remain permanently waterlogged. Larger or more engineered versions, sometimes with amended soils or drainage components, are often described as bioretention systems.

Rain gardens can slow water that would otherwise run quickly across roofs, pavement and compacted ground. Slower flow can reduce the amount of runoff reaching drains and streams at once, and soil and vegetation can retain or filter some pollutants carried by that runoff. Plants also provide food or shelter for pollinators and other wildlife. Actual performance depends on the volume of runoff, the garden's size and construction, soil infiltration and local rainfall; a rain garden is one part of stormwater management, not a substitute for every drainage or flood-control measure.

A suitable location and design are essential. Before construction, planners assess where runoff flows, how quickly the soil drains and whether water can overflow safely during unusually heavy rain. The feature should be located away from building foundations and should not be placed in ground that is already persistently wet or unsuitable for infiltration. Underground utilities must be identified before digging. Plant selection should match the garden's wet and dry zones as well as local climate; locally appropriate native plants may support local wildlife.

New plantings may need watering while they establish, and gardens generally need periodic weeding, inspection and upkeep of inlets and overflow routes. If water remains for too long, soil or design issues may need attention. In areas with poor infiltration, high groundwater or other site constraints, a rain garden may need a different design or may not be suitable without professional guidance. Local stormwater rules and site conditions determine what is appropriate.