Car Care Information

Residential Car Washing and Stormwater

When a car is washed on a paved surface, like in a driveway or in a parking lot, the soap, detergent, automotive fluids, oil, heavy metals, and roadway dirt that are rinsed from the vehicle goes straight into nearby storm drains. Storm drains convey water to the nearest river or stream without treatment. This contaminated runoff, even runoff containing biodegradable soap, can cause significant harm to aquatic plant life, fish, and other animals. 

You can wash your car and prevent stormwater pollution if you:

  • Park the car on grass or an area where the water can filter into the ground and not run off to the storm drain. If the driveway drains to an area where it can infiltrate, that works too.
  • Divert the drainage away from the storm drain.
  • Use a hose with a shut-off valve to reduce possible runoff from the grassy area.
  • Dump your soapy water out in the sink or on an area where it will filter into the ground.
  • If you don’t have a good place at home to wash your car, we ask you to take it to a commercial car wash (either self-serve or machine wash) where the wash water drains to the sanitary sewer.

Stormwater Facts

  • Puget Sound is the largest estuary in the continental United States by water volume. The Puget Sound coastline lies within 12 Washington State counties; a total of 14 counties are within the entire watershed.
  • Did you know the biggest pollution challenge to Washington’s streams, lakes, and marine water in urban areas is stormwater? The stormwater from one outfall may collect drainage from a large area with hundreds of homes, businesses, and parking lots. The accumulation of all the pollutants that run off those areas in the rain, especially after a dry period, adds up to a lot of pollution. We all need to be mindful of how we wash cars, pick up after our pets, and take care of our yards so we can prevent pollution.
  • Water that enters the storm drain in Duvall and other urban areas, goes directly through the pipes to streams, lakes, bays, and Puget Sound. In most areas, the stormwater does NOT go to a sewer treatment plant like the water that goes down the drain inside your house. Stormwater carries all the pollutants with it directly to our surface waters—soapy water and all.

The City also has a SudSafe Car Wash Kit available for check out to be used for your car wash fundraiser. Contact Public Works at 425.788.3434 or Email for more information or to reserve the kit.

SudSafe Kit