Potomac Water Hardness & Quality Report (2026)

Potomac, Maryland, in Montgomery County along the Potomac River — one of the most affluent communities in the United States, a major Washington DC western suburban community adjacent to the Great Falls of the Potomac (Chesapeake and Ohio Canal National Historical Park), home of the National Institute of Standards and Technology (NIST) campus, and a prestigious community with numerous ambassadors, senior government officials, and tech executives among its residents — draws its municipal water supply from the Potomac River via the Washington Suburban Sanitary Commission (WSSC Water). Water hardness in Potomac measures 113.5 mg/L — classified as moderately hard.

Potomac's moderate hardness — harder than the Bethesda zone (95 mg/L) but softer than Prince George's County zones — reflects the WSSC Water distribution characteristics in the western Potomac–Great Falls corridor. The Potomac Water Filtration Plant treats the Potomac River supply for Montgomery County. The Potomac community's distribution infrastructure — serving one of Montgomery County's largest residential zones — includes mains of varying ages from the 1950s–1990s Potomac suburban buildout era, accumulating moderate mineral content from the treated Potomac River supply, producing the moderate 113.5 mg/L.

At 113.5 mg/L, Potomac residents encounter moderate scale accumulation. Faucet aerators and showerheads develop deposits after several months — monthly cleaning with citric acid solution is practical maintenance. WSSC Water consistently delivers water meeting all Maryland MDE and EPA Safe Drinking Water Act requirements.