Let the pros handle car wash

Washing your car at home is a distinctly American hot weather ritual.

But it’s better to see a professional. Rivers and streams will be healthier for it.

The message runs counter to the bad rap that commercial carwashes still fight, nearly 20 years after the federal Clean Water Act began requiring operators to treat wastewater in a far more environmentally responsible way than most driveway washers do.

About 38 percent of Americans prefer to wash their cars at home, according to a survey by the International Carwash Association, although that’s down from 48 percent in 1996. Who hasn’t seen a movie or music video with a girls-washing-cars-in-bikinis scene? The DIY carwash culture, like car culture, is a part of us.

Here’s why it shouldn’t be, according to the Environmental Protection Agency, the Oregon Environmental Council and the Portland Bureau of Environmental Services:

Commercial carwashes waste less water than Driveway Guy – or school or community groups that wash cars to raise funds. They can’t afford not to conserve; water is the lifeblood of their business. According to Stormwater: The Journal for Surface Water Quality Professionals, most commercial carwashes use 60 percent less water to soap and rinse a car than a home wash uses just to rinse it.

Drive-in carwashes save water by recycling it, said Brett Hulstrom, an environmental specialist with the Portland Bureau of Environmental Services. Clean water rinses the first car, moves through filters where dirt and other impurities are removed, then gets mixed with chemicals to create soap for the next car.

Water waste, however, isn’t the biggest mark against at-home washes; it’s their impact on streams and rivers.

Commercial carwashes must send wastewater through a treatment facility – like the path toilet water takes after a flush – before it reaches rivers and streams. But the soap, oil and grease that sluices off a car in a driveway or street flows into storm drains, which often carry it straight into creeks and rivers.

There, any phosphorus from the soap encourages algae growth, which blocks sunlight and steals oxygen from fish. Oil and grease can coat fish gills and harm other water-dwellers, such as snails, insects and worms.

A home washer can reduce the damage by washing a car on the lawn, where soil soaks up some of the toxins; attaching a water-saving nozzle to the hose; and dumping sudsy water in the toilet or sink, not into the street.

The Oregon Environmental Council recommends home washers use no-soap cleaners labeled “nontoxic” or “phosphate-free.” But those gentler cleaners, often labeled biodegradable, can still harm aquatic life before they degrade.

Some carwashes are offering a fundraising option in which schools and other nonprofit groups can buy coupons for a commercial wash. The groups resell the coupons at a markup to raise money, eliminating the need to actually wash any cars.

Nobody’s going to make a music video about selling coupon books. But the fish will be pleased.