In Vermont, the dirty wastewater from car washes must go to a wastewater treatment facility. At some car washes, the wastewater goes through an oil/water separator before entering the treatment plant. Other car washes recycle their wastewater before sending it to the sewer.
In New York State, wastewater from the car washing must be treated by a municipal wastewater treatment facility holding a permit from the New York Department of Environmental Conservation State Pollutant Discharge Elimination System (SPDES), if such a facility is available. If not, the car wash owner must obtain a SPDES permit for the treatment and discharge of washwater from the facility. The treatment must be designed by a licensed professional engineer, constructed in accordance with plans approved by NYDEC and there are requirements for periodic testing of the effluent. Stormwater runoff from an existing car wash does not have to be permitted or treated as long as there are no contaminants in the runoff in excess of state discharge limits.
If you wash your car in your driveway, all that dirty water which can contain phosphorus and toxic chemicals, can run off into a storm drain. Often the storm drain may take that polluted water directly to your local lake or river. You can help keep waterways cleaner, by washing your car on a lawn to filter out the runoff, or taking it to a commercial car wash.
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I was actually thinking about that, too. Thanks for this informative post. I will be careful the next time I wash my car, or better yet, take it to a car wash service that cares for the environment.