It takes thousands of miles of pipeline to collect wastewater from homes and businesses so it can be treated and returned to the environment.

WSSC Water's Wastewater Collection System spreads across 1,000 square miles of Montgomery and Prince George's counties to serve our 1.8 million customers. The system is primarily a gravity system - it relies on gravity to carry wastewater from your home through the system. Twenty-nine major sewer basins are used to cover the 1,000 square miles that we serve.

Sanitary System, Stormwater System

The sanitary sewer system that carries wastewater from homes and businesses to wastewater treatment plants is separate from the stormwater drainage system. The sanitary sewer system collects wastewater from your kitchen and bathrooms; the stormwater drainage system collects rain, snowmelt and other water that runs off the land into storm drains. No sewage or water that goes down your drains enters the stormwater system.

Sanitary Sewer Overflows

Our separate systems help to protect local waterways. However, even a separate sewer system can experience an overflow if a pipe gets blocked. Sewer pipe blockages, which are major factors in more than 58 percent of sewer overflows, have many causes, including debris, grease or roots that can clog the pipes.

When a pipe is blocked, the system can experience what's known as a Sanitary Sewer Overflow - the discharge of untreated wastewater or partially treated wastewater. If you are aware of an overflow, call WSSC Water at 301-206-4002. To learn of any current events, see our Sewer Service Alerts page. You can also view our Sanitary Sewer Overflow reports, which are reported within ten days of an event.

Through our Sewer Repair, Replacement and Rehabilitation Program - the SR3 Program - WSSC Water is dedicated to reducing system overflows. Learn more about SR3.

Another dedicated effort to keep the sewer system clear is the Fats, Oils, and Grease program. It was established in 1994 to combat grease that is discharged illegally by restaurants and fast-food establishments.

Wastewater Treatment Plants

WSSC Water operates six Water Resource Recovery Facilities that clean an average of 70 million gallons of wastewater every day. The Blue Plains Advanced Wastewater Treatment Plant, which is operated by DC Water, also treats wastewater under a cost-sharing agreement with WSSC Water. All of our major WRRFs have been upgraded to use Enhanced Nutrient Removal technology.

System Maintenance

Most of our sewer pipes were constructed in the late 1940s and early 1950s, and are nearing the end of their useful life. WSSC Water is in the midst of sewer improvement projects that will extend the useful life of the aging system by renewing, replacing, and repairing the pipes. The work will extend the sewer system's life up to 100 years and eliminate sewer overflows and basement backups. The Sewer Reconstruction Program includes comprehensive sewer basin studies and sewer main, manhole and house connection reconstruction and replacement.

Last Modified: February 19, 2021, 2:22 pm EST