Wastewater Collection System

WSSC has been serving the residents of Montgomery and Prince George’s counties since 1918. Our mission is to provide safe and reliable water to our customers and return clean water to the environment, all in a fiscally responsible manner.

Wastewater Collection System

  • Serving a 1,000-square-mile area in Montgomery and Prince George's Counties, WSSC maintains more than 5,400 miles of sewer mains. Laid end-to-end, that would be enough pipe to stretch from Laurel, Maryland to Las Vegas, Nevada and back!
  • Serves 1.8 million residents.
  • WSSC's sewer system is primarily a gravity system - hence the fact that a majority of the pipes follow streambeds at the lowest elevation in the basin. There are 29 major sewer basins within our service area.

Sanitary Sewer Overflows

  • WSSC’s communities are served by a sanitary, or separate, sewer system meaning the pipes that carry wastewater from homes and businesses to wastewater treatment plants are separate from the storm water drainage system. The stormwater drainage system includes all precipitation that runs off the land and flows into storm drains and other catchment areas – no sewage or water from sinks or tubs enters the stormwater system.
  • A sanitary sewer overflow (SSO) is an event where untreated or partially treated wastewater discharges from a sanitary sewer system into the surrounding areas. WSSC releases Sanitary Sewer Overflow Reports for these types of incidents. Call 301-206-4002 for questions. See In Your Neighborhood for open emergencies.
  • Some SSOs occur in heavily wooded areas, and are difficult to locate, contain, relieve, and inspect. WSSC personnel determine the overflow volume based on an actual measurement, an estimate using best professional judgment, or by visual observation of evidence in the overflow area (or a combination thereof).
  • WSSC’s separate system protects local waterways from stormwater-related events; however, even a separate sewer system can experience an overflow event if there is a blockage in one of the pipes. Blockages in sewer pipes are major factors in more than 58 percent of sewer overflows. Blockages have many causes including grease, roots, and debris in sewer pipes.
  • In 1994, WSSC established the Fats, Oils and Grease (FOG) Program to address grease discharged illegally or through improperly maintained grease abatement systems in restaurants and fast food establishments. You can help prevent blockages by learning more about WSSC’s FOG Program and the “Can the Grease” campaign.
  • Visit the Sewer Repair, Replacement and Rehabilitation Program (SR3 Program) page to learn more out how WSSC is working to reduce sewer overflows.

Wastewater Treatment Plants

  • WSSC operates six Wastewater Treatment Plants (WWTPs) that clean an average of 70 million gallons of wastewater each day. The Blue Plains Advanced Wastewater Treatment Plant, operated by DC Water, handles as much as an additional  169 MGD under a cost-sharing agreement with WSSC, treating on average approximately 65% of the Commission’s wastewater annually.  Overall, WSSC cleans over 70 billion gallons of wastewater every year.
  • WSSC upgraded all major WWTPs to utilize advanced Enhanced Nutrient Removal (ENR) technology.
  • WSSC operates 52 wastewater pumping stations and 2 wastewater storage facilities.

System Maintenance

  • Most of WSSC’s sewer pipes were constructed in the late 1940s and early 1950s, and are nearing the end of useful life.
  • WSSC is in the process of implementing various sewer improvement projects that will extend the useful life of the aging sewer system by renewing, replacing, and repairing the sewer pipes.
  • This sewer rehabilitation will extend the life of the existing sewer system 50 to 100 years, eliminate sewer overflows and basement backups, and allow the WSSC to comply with a Consent Decree reached with the U.S. Environmental Protection Agency, the Maryland Department of Environment and several local environmental groups.
  • The Sewer Reconstruction Program is among WSSC's proactive initiatives aimed at effectively operating and maintaining our wastewater collection system. The program encompasses comprehensive sewer basin studies and sewer main, manhole and house connection reconstruction and replacement. Funding for the Sewer Reconstruction Program has increased substantially since its inception in 1979.
  • WSSC’s recently established Sewer Repair, Replacement and Rehabilitation Program (SR3 Program) is part of an effort to minimize, and, if possible, eliminate SSOs in the more than 5,400 miles of sewer mains that WSSC maintains.
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