Wash Water (Gray Water)


Wash water, gray water, and septic system wastewater are among the many common stormwater pollutants that can degrade water quality. Stormwater runoff containing wash water and gray water has been found to contain high concentrations of pathogens such as bacteria, parasites, and viruses. When they wash into our recreational waters they can make people sick with sore throats, intestinal problems, rashes, nausea, and eye and ear infections. Wash water also contains nutrients such as phosphorus and nitrogen, that fertilize aquatic algae blooms and promote bacterial growth which can degrade water quality. If you want to use a gray water system in your landscaping, please refer to the Department of Environment Health program and regulation.

What can I do?
Use Best Management Practices (BMPs)!
BMPs are techniques or controls used to prevent or reduce the discharge of pollutants, such as wash water and gray water, into the stormwater conveyance system also known as the storm drain system.



  • Drain washing machine water to sewer or septic system, unless an approved gray water system has been installed.