In the eco-friendly world do-it-yourself options are usually the way to go.  However, when it comes to car washing the better choice is actually to take your car to a car wash.  Unlike household waste water that enters sewers or septic systems and undergoes treatment before it is discharged into the environment, what runs off from your driveway while car washing goes right into storm drains.  Eventually the water in the storm drains makes its way into rivers, streams, creeks and wetlands where it poisons aquatic life and wreaks other ecosystem havoc.  That dirty water is full of gasoline, oil, exhaust residue and chemical laden detergents, none of which are good for the environment.  On the other hand, federal laws in the U.S. require commercial carwash facilities to drain their wastewater into sewer systems, so it gets treated before it is discharged back into the environment.

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.  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.  If you are washing your car at home using the hose method, buy an automatic shut-off valve so the water is not continuing to flow as you wash.  To cut back on water use you should also only the hose to spray of the car twice, once at the start and once to rinse.

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 waste water 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.

Some companies have come out with waterless car wash cleaners. The biggest issue with these is the time involved. You'll spend more time going over your car with a cloth and a waterless cleaner, but you will save water, and these cleaners are typically earth-friendly, although not all, so read the fine print. Some waterless car wash products include:

Eco-Touch Waterless Car Wash

Freedom Waterless Car Wash

Dri Wash

No Wet

Lucky Earth