Rebates for Rain Gardens and Cisterns

RainWise is a rebate program that helps property owners manage stormwater by installing cisterns and/or rain gardens on private property. This prevents flooding, adds attractive landscaping, and can provide water for summer irrigation. To receive a rebate, you must live in an eligible combined sewer overflow (CSO) basin.

The Rebate Process

The RainWise Program provides rebates that cover most or all of the cost of installing cisterns and/or rain gardens on your property. To receive a rebate, you must be in an eligible combined sewer overflow basin and work with a RainWise-trained contractor. The rebate can be up to $4.00 per square foot of rooftop runoff controlled. Talk with a contractor about what you can do on your property and ways to maximize the rebate. The average home rebate is about $4,300.

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Cisterns & Rain Gardens

During big storms, polluted runoff can cause sewer overflows and erode hillsides and stream banks. Rain gardens and cisterns can help control this problem.



A cistern is a large above-ground tank, like a giant rain barrel, used to collect roof water. RainWise cisterns slowly release collected water back into the storm sewer to help reduce combined sewer overflows.

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Rain Gardens

A rain garden is a shallow depression containing spongy soil and a variety of plants. Rain gardens collect water from your roof downspout and allow it to safely soak into the ground.

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Looking for more information about RainWise?

Visit our Tools & Resources section for informational brochures, webinars, grant information and much more!

Big Roofs: Beyond Residential

We encourage community centers, religious organizations, apartment buildings, businesses and other large buildings to participate in the RainWise program. The bigger the roof, the bigger the rebate to keep Puget Sound and its surrounding waterways clean.

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On-going maintenance is essential to keep your RainWise installation working properly. We are counting on your RainWise project to prevent polluted stormwater from going into our waterways. RainWise requires homeowners to maintain their RainWise project for five years.

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Not sure where to find arborists’ wood chips for fresh mulch? Need help with rain garden plants and weeds? Wondering how often or how long to water your new rain garden? Contact the Garden Hotline at 206-633-0224 or help@gardenhotline.org

Multi-lingual service provided.

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