Bethesda Water Hardness & Quality Report (2026)

Bethesda, Maryland, an unincorporated community in south-central Montgomery County adjacent to Washington DC — one of the Washington DC metro area's most affluent communities, home of the National Institutes of Health (NIH) campus and the Walter Reed National Military Medical Center — draws its municipal water supply from the Potomac River via the Washington Suburban Sanitary Commission (WSSC Water) Potomac Water Filtration Plant, distributing to the inner Montgomery County Bethesda–Chevy Chase corridor. Water hardness in Bethesda measures 145 mg/L — classified as moderately hard.

Bethesda's moderate hardness reflects the WSSC Potomac supply distribution characteristics. The Potomac River at the WSSC intake (Potomac, MD area) drains the Shenandoah Valley calcareous carbonates and the Blue Ridge crystalline terrain. The inner Montgomery County Bethesda–Chevy Chase distribution zone — the most affluent and politically prominent area of the WSSC service territory — includes older residential infrastructure from the 1930s–1950s Bethesda–Chevy Chase build-out (when Bethesda emerged as the first Washington DC suburban expansion). The WSSC distribution in this zone has been substantially upgraded compared to more distant areas, producing the moderate 145 mg/L supply in the inner Montgomery County corridor.

At 145 mg/L, Bethesda 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.