Few people realize that washing our cars in our driveways is one of the most environmentally un-friendly chores we can do around the house. Unlike household wastewater that enters sewers or septic systems and undergoes treatment before it is discharged into the environment, what runs off from your car sweeps down your driveway (an impervious surface) and goes right into storm drains—and eventually into rivers, streams, creeks and wetlands where it poisons aquatic life and wreaks other ecosystem havoc. After all, that water is loaded with a witch’s brew of gasoline, oil, and residues from exhaust fumes—as well as the harsh detergents being used for the washing itself.

Commercial Car Washes Treat Waste Water

On the other hand, federal laws in both the U.S. and Canada require commercial carwash facilities to drain their wastewater into sewer systems, so it gets treated before it is discharged back into the great outdoors. And commercial car washes use computer controlled systems and high-pressure nozzles and pumps that minimize water usage. Many also recycle and re-use the rinse water.

The International Carwash Association, an industry group representing commercial car wash companies, reports that automatic car washes use less than half the water of even the most careful home car washer. According to one report, washing a car at home typically uses between 80 and 140 gallons of water, while a commercial car wash averages less than 45 gallons per car.

Think Green When Washing Your Car

If you must wash your car at home, choose a biodegradable soap specifically formulated for automotive parts, such as Simple Green’s Car Wash or Gliptone’s Wash ‘n Glow. Or you can make your own biodegradable car wash by mixing one cup of liquid dishwashing detergent and 3/4 cup of powdered laundry detergent (each should be chlorine- and phosphate-free and non-petroleum-based) with three gallons of water. This concentrate can then be used sparingly with water over exterior car surfaces.

Even when using green-friendly cleaners, it is better to avoid the driveway and instead wash your car on your lawn or over dirt so that the toxic wastewater can be absorbed and neutralized in soil instead of flowing directly into storm drains or open water bodies. Also, try to sop up or disperse those sudsy puddles that remain after you’re done. They contain toxic residues and can tempt thirsty animals.

Waterless Car Wash Products are Good for Small Jobs

One way to avoid such problems altogether is to wash your car using any number of waterless formulas available, which are especially handy for spot cleaning and are applied via spray bottle and then wiped off with a cloth. Freedom Waterless Car Wash is a leading product in this growing field.

A Better Car Wash Option for Fundraising

One last caution: Kids and parents planning a fundraising car wash event should know that they might be violating clean water laws if the run-off is not contained and disposed of properly. Washington’s Puget Sound Carwash Association, for one, allows fund-raisers to sell tickets redeemable at local car washes, enabling the organizations to still make money while keeping dry and keeping local waterways clean.

EarthTalk is a regular feature of E/The Environmental Magazine. Selected EarthTalk columns are reprinted on ThoughtCo by permission of the editors of E.

Edited by Frederic Beaudry.