Clean Car, Clean River: Watershed-Friendly Ways to Wash Your Vehicle

Paul Racette, Pennsylvania Environmental Council

When the sun shines and temperatures become mild, many want to get out of the house, even if it is just to wash their car. A bucket of warm soapy water, some soft sponges and drying towels, hook up the hose, and off you go to spiff up your wheels. But what does washing your car have to do with clean water and happy fish?

In most Pennsylvania towns and cities, the storm drains connect to pipes that carry runoff directly into our nearby streams and rivers. About 40 percent of the neighborhoods in Philadelphia have storm drains that flow into our waterways. Those waterways include the Delaware and Schuylkill Rivers, sources of our drinking water! That soapy water, dirt, and anything else flowing into storm drain inlets goes directly to the homes of our fish, turtles, ducks, and other water loving creatures. If you are a do-it-yourself car washer that sudsy, oily, grimy rinse water will go into a storm drain and impact our drinking water.

Remember, only rain should go into that drain. So, is there a water-wise way to wash your car?

The best thing to do is support neighborhood businesses: take your auto to the drive-through car wash, which captures, reuses, and treats all that dirty and soapy water onsite or at a waste-water treatment plant. 

Of course, handling waste is just half the equation – commercial car washes also use far less water to begin with. As The New York Times points out, rinsing your car with a hose at home can use 100 gallons of water, according to the Southwest Car Wash Alliance. Compare that to self-service car washes, which can do the job with as little as 17 or 18 gallons. Even full-service car washes compare favorably to home washing, averaging about 30 to 45 gallons of water per vehicle according to a 2018 study by the International Carwash Association. Because they must pay for the water coming in and going out of their facility, these businesses are incentivized to maximize efficiency in a way that driveway car-washers are not. Most locations reuse wash water several times before sending it to a treatment plant.

If you just love to wash your own set of wheels, position your car on your grassy lawn or another non-paved surface if that is an option for you. Let the suds soak into the grass, gravel, or dirt rather than run down the pavement. If you can’t avoid washing on pavement, pick an area that drains towards a vegetated area rather than directly into the street or storm drain.

Again, the best way to minimize the effect washing your car has on the environment is to use a commercial car wash. However, if you choose to wash your car at home or on the street, there are things that you can do to minimize the water quality impact:

At A Glance, water saving tips for car washing:

  1. Avoid storm drains and park your car on grass or an area where the water can filter into the ground.  
  2. Keep the drainage away from the storm drain. Many local governments lend out pump kits at no cost. These pumps temporarily plug the storm drain and pump the dirty water to the sanitary sewer, thereby preventing the runoff ending up in a river.
  3. Dispose all your soapy water out in the sink or into the ground.  
  4. There are also eco-friendly commercial car washes where the wash water drains to the sanitary sewer. Some car washes recycle water before letting it run down the sewer drains. Saving the planet and some time? Sounds like a great idea!

About the Author: Paul Racette is a Program Manager for Watersheds at the Pennsylvania Environmental Council (PEC). PEC protects and restores the natural and built environments through innovation, collaboration, education, and advocacy. Through a partnership with the Philadelphia Water Department, PEC is raising awareness of the effects of water pollution via stormwater runoff. For more information, visit their stormwater page at https://pecpa.org/program/stormwater-education 

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