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.
To help prevent stormwater pollution, the City is regulated by State and Federal stormwater regulations. The City has a stormwater discharge permit (AZS000003) under the Arizona Pollution Discharge Elimination System (AZPDES) which is issued by the Arizona Department of Environmental Quality (ADEQ). Under this permit, the COP has developed and implements a Stormwater Management Plan (SWMP) in order to reduce and/or eliminate stormwater pollution. The Phoenix Stormwater Management Program's activities are summarized in the City of Phoenix's Municipal Separate Storm Sewer System (MS4) Annual Report.