For many of us, summertime means road trips to the beach or mountains, or at the very least some additional dust and bird poop on the exterior of our vehicles. The extra grime leads us to do one of two things: wash our car in the driveway or head to the car wash. But which choice is better for the environment?

The main concerns with either choice are the amount of fresh water being used and the types of chemicals used to scrub the dirt. Both of these concerns can be closely monitored when washing the car at home, says Katy Gresh, spokeswoman for the Southwest Region of the Pennsylvania Department of Environmental Protection. She advises car owners to put aside a set amount of water for the entire wash. “It’s just like brushing your teeth,” she says, “You don’t want to leave the water running or use more than you need for the job.” But even following this advice comes with an environmental risk: Washing your car in the driveway or street flushes the dirty water into storm drains.

John Schombert, executive director of 3 Rivers Wet Weather, says it’s never a good idea to wash a car on asphalt. His organization works to educate the public about storm sewers and water runoff, keeping this untreated water from entering the Allegheny region’s waterways. “We ask people to consider washing their cars on lawns or other [permeable surfaces] where the water gets absorbed,” Schombert says.

“Soil can break down and help filter those things,” Schombert says. “Storm sewers are not made for waste disposal.” Even when car owners use natural soaps to wash their cars, which Schombert says are probably ineffective at breaking down grease anyway, they are still rinsing debris from the roads and salt and tar into the storm sewers.

The commercial car wash down the street knows full well the rules regarding wastewater in storm sewers. According to the International Carwash Association (ICA), a professional organization for the car washing and detailing industry, professional car washes must use water reclamation systems. These mandated processes not only keep the dirty water out of storm sewers and regular water treatment systems, but they also work to reduce water usage at commercial facilities.

As The New York Times points out, rinsing your car with a hose at home can use 100 gallons of water at home, according to the Southwest Car Wash Alliance. Compare that to self-service car washes, which allow you to use only about 17 or 18 gallons of water. And most full-service car washes average about 30 to 45 gallons of water per vehicle, according to a 2018 study by the International Carwash Association.

Car washes work to save water

The ICA encourages everyone to consider commercial car washes and promotes programs like WaterSavers, educating commercial car washes about environmentally sound practices. The ICA lists participating facilities on their website to help consumers locate car washes that are meeting the WaterSavers requirements.

Compliant car wash owners like John Richard of Rapidwash in Bethel Park, Pennsylvania., are excited about the program because it helps to market services that are having a significant impact on the environment. Using water reclamation systems at his facilities, Richard was able to reduce his fresh water consumption from 60-plus gallons per vehicle to 8 gallons. These are better results than national ICA research, which found the average commercial car wash uses 43.3 gallons of water per vehicle and saves about 40% with water reclamation. Richard says the average car owner uses around 110 gallons to wash a car at home, making WaterSavers-compliant commercial car washes a great alternative.

“We’re excited [about the WaterSavers program] because we’re always trying to stay on the cutting edge in the industry,” he says, mentioning that his business is starting to collect rainwater to further reduce fresh water use and makes a point to use biodegradable products to wash and treat the vehicles they service. Rapidwash also is making changes to cut back on electricity usage. “We’re doing little, easy things that really make a big difference to our surroundings and to our bottom line, cost-wise.” Some car wash businesses advertise “100% Fresh Water” or similar slogans to lure in customers, but Richard points out that this means increased strain on natural resources and doesn’t really provide a better quality result.

So, other than checking the ICA website before heading to the car wash, how can you make sure you’re visiting a facility that is as conscientious as Rapidwash? Richard suggests asking car wash operators if they reclaim their water, use biodegradable chemicals, and treat water before sending it to the sewage treatment plant.

Editor's note: This story has been updated with new information since it was published in April 2010.

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