Did you know that vehicle washing can contribute pollutants to our rivers and streams – depending on where your vehicle is cleaned? Dirty water from commercial car washes goes into the city’s sanitary system and is treated at the regional wastewater treatment plant. However, soap suds and water run-off from vehicle washing on driveways, parking lots and streets typically flows along the gutter and into a storm drain before it empties into a creek or river.
Soap is only one part of the discharge problem. Even if only water is used, there’s a mix of pollutants including oils, grease, heavy metals, particulates from vehicle exhaust emissions and brake linings and rust being washed down the drain. Adding soap to the mix may introduce phenols, dyes, acids and ammonia. And even more potentially harmful ingredients are found in spray-off tire cleaner.
What's Wrong WIth Soap?
The detergents in car wash cleaners affect fish in several ways. All detergents contain a surfactant so that the cleaner rinses off easily with water. Surfactants destroy the external mucus layers that protect fish from bacteria and parasites, causing severe damage to their gills. Even in low concentrations, surfactants will kill fish eggs. Detergents can lower the surface tension of water, allowing organic chemicals—such as pesticides and phenols—to be more easily absorbed by fish. Soaps that contain phosphates promote plant growth and can cause excess algae growth in waterways. As these plants decay, large amounts of oxygen are consumed, leaving very little oxygen available for fish.
Commercial Car Washes
There are some environmental advantages to washing your car at a drive-through or self-serve commercial car wash. Commercial car washes drain used water into the sanitary system instead of storm drains. This water is treated to remove pollution before it is discharged into our local waterways. Plus, conveyor car washes can use substantially less water, depending on the equipment used. Advanced, computerized pumps and nozzles control water output, reducing the amount of water used by up to 60 percent compared to a home wash. Special pressure nozzles mix air in with the water to create pressure without volume. Some even recycle and reuse water on site.
Be Stormwater Smart at Home
If you plan to wash your vehicle at home, here are some earth-friendly tips. If you wash with more than water, choose soaps, cleaners or detergents labeled phosphate-free and biodegradable. Vegetable or citrus-based soaps are the safest products. Before you get started, sweep driveways to prevent leaves and trash from being carried to the storm drain. Control water volume by using a spray nozzle and if possible wash your car in an area where runoff doesn’t flow to the street (gravel or grassy areas). If your wash area is paved and slopes toward the street, try rolling up a few towels to divert run-off to a lawn. When you are done, discard dirty wash water onto your grass, flower bed or into the sink.