The Problem with Car Washing

When a car is washed on a paved surface, like in a driveway or in a parking lot, the soap, detergent, automotive fluids, oil, and roadway dirt that gets rinsed from the vehicle goes straight into nearby storm drains. These storm drains lead directly to lakes, streams, and bodies of water in the Puget Sound area. This contaminated runoff, even runoff containing biodegradable soap, can cause significant harm to aquatic plant life, fish, and other animals. In short, something as seemingly harmless as a car wash can cause serious damage to local water quality.

How can you wash your car and help keep our waters clean?

Residential car washing:

  • The best option is to take your car to a commercial car wash, especially if you plan to clean the engine or the bottom of your car. Most car washes reuse wash water several times before sending it to the sewer system for treatment.
  • Use soap sparingly. Use a hose nozzle with a trigger to save water.
  • Pour your bucket of soapy water down the sink when you're done, not in the street. Or wash your car on a grassy area so the ground can filter the water naturally.

Charity car washes:

Sell tickets from your local commercial car washes.

You buy them at a discounted price, sell them at a profit, and keep the difference for your selected charity! Commercial car washes reuse water several times before sending it to the sewer system for treatment, conserving water AND preventing pollutants from reaching our waterways. Contact one of the following to get started today!

Charity groups:

Help preserve Washington’s waters for future generations-- be a leader in reducing pollution flowing to Puget Sound. Contact your desired host location in advance, and use the Charitable Car Wash Group General Guidelines (pdf) to start setting up your car wash event!


For questions contact the Seattle Public Utilities EPT Resource line at (206) 684-7624 or by email at