Two Types of Sewer Systems

There are two types of sewer systems in the City: a separate sewer system and a combined sewer system. Separate sewer systems have two separate pipes, with one pipe conveying stormwater from and one pipe conveying sanitary sewer. Combined sewers have one pipe that conveys a mix of sanitary and stormwater.

Page updated on Oct 20, 2017 at 4:25 PM

There are two types of sewer systems in the City of Alexandria: a separate sewer system and a combined sewer system. 

Separate Sewer Systems

Separate sewer systems have two separate pipes. One pipe carries stormwater (rain water) from storm drains to local streams. Pollution and trash in stormwater flows to local streams with little or no treatment. A second pipe carries sanitary sewage to the wastewater treatment facility, where Alexandria Renew Enterprises cleans the sewage.  The separate sewer system serves 95% of the City. 

Visit www.Alexandriava.gov/Stormwater to learn more about what the City is doing to reduce pollution and flooding through Stormwater Management. 

 Separate Sewer System


Combined Sewer Systems

Combined sewer systems only have one pipe. Sanitary sewage from inside homes and businesses flushes and drains to the pipe. When it rains, stormwater flows into the same pipe and mixes with raw sewage. The combined sewer system serves about 5% of the City in the historic Old Town area.  In dry weather, all sewage flows to the wastewater treatment facility, where Alexandria Renew Enterprises cleans the sewage. When it rains, there can be 9 times more stormwater than raw sewage. The stormwater  can overwhelm the combined sewer system. When this happens, the mixture may overflow into local streams through one of the four permitted combined sewer outfalls. 

Visit www.Alexandriava.gov/Sewers to learn more about what the City is doing to reduce the impacts of the combined sewer discharges on the environment.

Combined Sewer System

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