PrintProfession car washes and water quality and conservation

If your car’s dirty, well it’s not just dirt- it’s grime that contains heavy metals, oil, and toxic chemicals.

When it comes to water quality, keeping your car clean is better than letting the rain rinse heavy metals, oil, and toxic chemicals off your car and, ultimately, into the Puget Sound.  This toxic mix of chemicals has a deadly effect on aquatic life.  How you choose to wash your car is also important.  When you wash your car in your driveway, the soap and chemicals can go into the storm drain, polluting our streams, rivers, and the Puget Sound.

Citizens of the region can help decrease water pollution caused by run off from cars by taking their car to a professional car wash or by washing their car over gravel or lawn.

With over 3 million cars in King, Pierce, Thurston, and Snohomish Counties, it’s widely recognized that cars contribute significant pollution to the Puget Sound. Three million cars contribute an estimated 9,194 gallons of gasoline, diesel, and motor oil, 19,355 pounds of phosphorous and nitrogen, 2,903 pounds of ammonia, and 1,451,613 pounds of solid waste into our waterways annually.

Professional car washes use oil/water separators that remove pollutants, which are ultimately pumped out and properly disposed of, and their wastewater is discharged into the sanitary sewer.  In addition, professional washes use minimal water, compared to home car washing; though washing your car at home over gravel or the lawn allows polluted water to absorb into the ground and keeps it from running into the storm drain.

The Puget Sound Car Wash Association is a leader in the effort to protect streams, lakes, and the Puget Sound from pollution caused by washing cars and trucks.  We offer nonprofit organizations a car wash ticket program as an alternative to parking lot car washes. We have been awarded King County’s Earth Hero Award as an industry leader for innovative and effective environmental programs, and have received the Community Service Leadership Award from the International Car Wash Association.

Here are some facts about car washes and water pollution:

Water Conservation

Professional, commercial car washes use water management technology developed through industry and university research that enables them to wash cars thoroughly with a fraction of the water a home car wash uses.


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  • High-pressure nozzles and pumps at car washes are designed to get the most use out of water flow.
  • Special pressure nozzles mix 50% air with water to create pressure without volume.
  • A ten minute home wash can use as much as 140 gallons, based on engineering studies that show a 5/8” hose running at 50 psi uses 14 gallons of water per minute (WCA figures). Other estimates: San Francisco Water Dept- 180 gal. San Antonio Water System- 150 gal. City of Toronto- 116 gal.
  • Professional car wash equipment can clean a car in just a few minutes, using between 15 and 60 gallons, depending on the equipment used and whether it is a self-serve or conveyor wash.
  • Comparison with other water uses: Dripping faucet: 25-30 gal./day toilet flush: 5-7 gal. 10-minute shower: 25-50 gal. Washing machine at top water level: 60 gal. Brushing teeth: 2 gal.
  • A car washed professionally does not waste water. There are few industries which use water as a resource that carefully manage water as well as the modern car wash.
  • For most people, their car is their second most valuable asset. Keeping it clean extends the life of the car.
  • Car washes provide jobs for thousands in the Puget Sound Region, and significantly contribute to its tax base.

Water Quality

  • Wastewater from driveway and parking lot car washing flows into the stormwater system and then into our waterways.
  • Driveway and parking lot car washing discharge consists of oils, grease, elements from brake linings, rust, trace amounts of benzene and possibly chromium. Adding soap to the mix introduces phenols, dyes, acids, and ammonia
  • The Seattle Stormwater Grading and Drainage Control Code listed unregulated car washing second in the eight high-risk pollution-generating activities.
  • Past EPA Administrator Christine Todd Whitman has been quoted as saying, “It may seem like a small amount of oil and grease, but collectively, these little sources add up to (the equivalent of ) 23 Exxon Valdez oil spills in the continental United States per year.”
  • Effluent from professional car wash facilities is filtered and piped to the sanitary sewer system.

*This list compiled from a variety of sources. The PSCWA is not responsible for its accuracy.