The Washington Suburban Sanitary Commission (WSSC) provides safe and reliable water, life’s most precious resource, and returns clean water to our environment.

WSSC is the 8th largest water and wastewater utility in the nation, serving nearly 1.8 million customers in Prince George’s and Montgomery counties. We operate and maintain eight water and wastewater plants, over 5,400 miles of fresh water pipeline and over 5,300 miles of sewer pipeline.

Our primary sources of water are the Potomac and Patuxent rivers. These rivers also provide water for our three reservoirs. The Patuxent River has two reservoirs, the Triadelphia and Rocky Gorge. The Potomac River feeds the Little Seneca reservoir. The total amount of water that all three reserviors can hold is 14 BILLION gallons!

There are two water filtration plants. One is located at in Montgomery County, and is right next to the Potomac river. The other is located in Prince George's County near Laurel, and is fed by water pumped over from the Rocky Gorge reservoir. Click here for an explanation of how our water is prepared for you to use.

Just what happens to the water you wash down the drain? Wastewater is sent to 6 different wastewater plants, where the water is cleaned and returned to the environment. Click here for an explanation of how this process is done.

WSSC was established in 1918, which makes us over 80 years old. Waste from Montgomery and Prince George's counties was polluting the streams that flowed into the District, and the city wanted them cleaned up. Once we were established, we bought existing water and sewage systems within our service area, to create a larger, regional system.

The first reservoir, Triadelphia, was created by the construction of Brighton Dam on the Patuxent River. This dam was completed in 1943. The Patuxent River Filtration Plant was constructed near Laurel in Prince George's County and opened in 1944. The T. Howard Duckett Dam and Rocky Gorge Reservoir were completed in 1952, bringing the water supply closer to the plant.

The Commission built the Potomac River Filtration Plant in Montgomery County to take water from the Potomac River, and opened it in 1961. In 1985, the Commission completed construction on Little Seneca Creek Dam and Reservoir.