The Patuxent and Potomac rivers are the sources of all the water we filter and process. The source water treated at the Patuxent Water Filtration Plant (WFP) is held in two reservoirs —Triadelphia and T. Howard Duckett (also known as Rocky Gorge)—and is pumped to the plant. The Potomac WFP draws water directly from the Potomac River. The map shows the approximate service areas of both plants. As indicated, some areas receive blended water, processed at both the Patuxent and Potomac WFPs.
Is My Water Hard or Soft?
Hard water contains more dissolved calcium and magnesium. Potomac water tends to be hard (typically averaging about 120–130 milligrams per liter). Patuxent water is soft (typically averaging about 60–65 milligrams per liter).