If you own a commercial carwash, you are required to use a District-approved oil/water separator. Before opening your business, you are required to contact the District's Engineering Department for specs and approvals. No discharge is allowed to enter the storm drain system or run off your property. Site improvement plans for these projects shall include grading and drainage plans signed and sealed by a professional engineer.
For more information, refer to the District's Design Standards and Policies located in Appendix 2 of the Master Bid Document (MBD) (PDF). See Section 10-06 Exterior Pavement Runoff to Sanitary Sewer. Call 707-644-8949, ext. 1100 for more information. Only individual residents washing their cars at home are exempt. The District encourages car owners to use commercial carwashes so that the pollutants coming off dirty cars are removed through the wastewater treatment process.
Businesses are not allowed to wash vehicles without using a District-approved oil/water separator. If you have a small number of vehicles, it may be more cost-effective to use a commercial carwash. Businesses engaging in charity car washes can learn more about mitigating stormwater runoff at our Charity Car Washes page.