When operating a charitable car wash, allowing wastewater to flow into storm drains (via streets and gutters) should be avoided and minimized to the extent practical. Wastewater runoff contains soap and oil residue, which should not be allowed to enter the storm drains. The following practices should be followed:
Remove all trash and debris from the car washing area before the event. Use only nontoxic, phosphate free or biodegradable soap. No acid-based wheel cleaners should be used. Consider contracting with a professional mobile car washing service or using rented pressure-washing equipment. High pressure/low volume equipment uses less than a 10th of the water conventional techniques do. If using conventional "hose and bucket" methods minimize runoff by:
Remember to clean up the site after the event otherwise they might hose the site down. This helps prevent stormwater contamination and will make the property owner more willing to allow future fund raising events.