About Rain Gardens

“What is a Rain Garden?” A rain garden is a bowl-shaped garden that, through the actions of spongy living soils and properly chosen plants, slows, filters, and absorbs runoff from roofs or pavement keeping it from becoming harmful storm water pollution. Rain gardens are a smart and proven way of using beautiful landscaping to: clean our waterways, protect our precious natural habitats, improve homes and neighborhoods, reduce flooding and save millions of dollars in pollution clean-up and massive utility construction projects.



The majority of our region’s Puget Sound pollution is caused by rainwater runoff from our streets, driveways, lawns and rooftops! In fact, 14 million pounds of toxins enter Puget Sound each year. Having clean air and water and beautiful natural areas is a major part of what makes Washington a great place to live. Waterways like Puget Sound, Commencement Bay and the Skagit River give us places to enjoy nature, fish and hike. Our waterways are central to our food source, and our local economies. But toxic runoff, the number one source of pollution to Puget Sound, is threatening the health of our water. Every time it rains, millions of gallons of toxic runoff wash into Puget Sound and our lakes and rivers, spreading poisons that threaten our health, environment and economy.

The Puget Sound Partnership has stated that inaction will “ultimately place a much higher burden on all of us – both economically, in health costs from exposure to toxic substances, and environmentally, in the loss of the stunning and vibrant life of Puget Sound, the economic engine for our state. Declines of fisheries, both commercial and recreational, have impacted all of Puget Sound. The alternative to the decentralized approaches of pollution and flood control like rain gardens and low impact development are expensive treatment plants like Brightwater ($2B) or allowing the Sound to die.”

raingarden sign macro691pixWide

As our region grows, native forests are replaced with roads, parking lots and other hard surfaces. Rain gardens act like native forests by collecting and absorbing rainwater that washes over hard surfaces, filtering out pollutants like motor oil, pesticides and heavy metals.

How to Build a Rain Garden


If you’re interested in how to build a rain garden, a step-by-step process can be easily learned by attending a rain garden workshop, studying the Washington State University Rain Garden Handbook for Homeowners (18MB PDF download) and viewing the “How to build a rain garden WSU” online video (below). You will learn rain garden design and construction basics like:

  • How to determine how much impervious surface you have, and how much of that water you want to manage.
  • How to decide where on the property you’d like to build your rain garden.
  • How to do a percolation test, to make sure the soils surrounding your rain garden plants can soak up the water.
  • How to decide how big of a rain garden to create in the space you have available.
  • How to implement rain garden construction next steps.
  • How to know what the best rain garden plants are.
  • How to maintain a rain garden.

You don’t have to be a gardener or an engineer to build a rain garden, but it is important to consider your site carefully before you get started.