The City of Phoenix has two separate sewer systems: storm drains and sanitary sewers. Storm drains carry rainwater UNTREATED to our rivers, washes and retention areas. Sanitary sewers carry water from toilets and sinks to your local wastewater treatment plant (WWTP) which treats sewer water to meet State and Federal surface water quality standards.
The City has a Arizona Pollution Discharge Elimination System (AZPDES) stormwater permit (AZS000003) issued by the Arizona Department of Environmental Quality (ADEQ). Under this permit, the City has developed and implemented a Stormwater Management Plan (SWMP) to reduce stormwater pollution. Program activities are summarized in the City of Phoenix's Municipal Separate Storm Sewer System (MS4) Annual Report.