Learn how rain gardens collect stormwater

Learn what rain gardens are and how they are included in flood projections 


Rain gardens are a type of green infrastructure built to mitigate pluvial (stormwater) flooding. A rain garden is a garden in a depressed area of a landscape that is designed to temporarily hold and soak in rainwater. Rain gardens reduce runoff from roofs, streets, and/or driveways. The amount of gallons of rainwater that a rain garden can hold depends on the square footage of the catchment area and the depth of the rain garden. In general, rain gardens are typically built to hold 1 inch of rainwater. The cost of rain gardens varies depending on whether you do it yourself or hire a contractor; the cost ranges from $5 - $45 per square foot. Some communities offer incentives to support the installation of rain gardens. To find out if your community does, check your local government website. 


NYC DEP green infrastructure rain garden rendering


Rain garden in front of someone’s home (photo courtesy of Candace Stoughton, August 2010)

Flood risk reduction

Information on Flood Factor comes from the First Street Foundation Flood Model. A rain garden is one of the 40 different types of flood risk reduction projects, known as adaptation, that this model considers when calculating and validating flood projections. 

The Adaptation Team continues to collect information on the flood infrastructure that exists across the country to make sure the Flood Model includes as many adaptation projects as possible. If you know of any projects that are not shown today, please help the team by submitting this flood protection project user input form. The adaptation database contains 23,000 features today. We know there are more projects to include and value your input!


Learn more 

Adaptation types

Adaptation methodology

How can local knowledge improve the Flood Model?

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