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1. What is a rain garden?

A rain garden is a bowl-shaped shallow planted area in the landscape where rain water collects and absorbs back into the soil. It mimics the natural environment of the undisturbed soils and forests that once covered the Puget Sound area. 

It is designed to slow, filter, and infiltrate runoff from roofs or pavement to safeguard local water quality. A rain garden uses spongy living soils and native plants to achieve its goal.

Learn more about rain gardens.

2. What is a rain garden's purpose?

Rain water picks up pollutants as it flows over hard surfaces such as rooftops, driveways, and compacted soils. These pollutants, like gasoline, motor oil, and pesticides, are then carried through storm drains directly into our local rivers, lakes, and streams. When rain water is allowed to soak back into the ground through a rain garden, some of these toxic materials are removed by plant and animal microorganisms living in the soil. Rain gardens also slow the flow of runoff to help with erosion control and flood prevention.

3. Why build a rain garden?

Building a rain garden adds a number of benefits to your home and your wallet.

• Rain gardens can beautify your home, adding to its value, while protecting your property and your community from flooding and erosion.
• They also provide habitat for bees, birds, butterflies and other wildlife, help improve air quality and reduced your carbon footprint.
• They are a proven way to reduce water pollution locally and regionally. 
• They're an affordable option for homeowners and utilities compared with traditional pipe and drain systems. They require minimal time and skill to maintain each year, and actually work better over time.
• Rain gardens help recharge local groundwater supplies.

Learn more about the benefits of rain gardens.

4. Why use recycled materials in a rain garden?

Reusing materials in your rain garden saves you money while benefiting your environment and community. Compost, soils, bark mulch, and garden stones are just a few ideas for easily obtained recycled materials. There are many options out there for almost any application in your garden.

5. Why use native plants in a rain garden?

In a rain garden, plant roots and soil organisms work together to help absorb and clean rain water runoff. Using native plants is best because they are naturally adapted to local pests and climate conditions, and can thrive without the use of fertilizers, pesticides, or excessive watering. Native plants also create habitat for local birds, butterflies, and beneficial insects by providing food and shelter. Learn more about native plants.

6. How can I build a rain garden?

You can do the work yourself with the help of a manual, or you can consult a local professional to design and install your garden. Download the Rain Garden Handbook for Western Washington: A Guide for Design, Installation, and Maintenance.

7. What is low impact development (LID)?

Rain gardens are just one of many techniques and design considerations that help capture and move rain water while improving the aesthetics of your property. Low impact development (LID) techniques are specifically designed to manage the rainwater that falls on your property by allowing some to evaporate back into the air, some to absorb into the ground, some to be captured and used later as needed, and the rest to slowly pass into the stormwater system and into nearby streams. Learn more about these techniques in our guide, Managing Rainwater: A Homeowners Improvement Guide for Low Impact Development (LID) in Bothell.