Manassas Water Hardness & Quality Report (2026)

Manassas, Virginia, the Prince William County independent city — the site of two major Civil War engagements (the First and Second Battles of Bull Run/Manassas, 1861 and 1862, defining battles of the eastern theater), a major Northern Virginia exurban community on the Manassas–Prince William County growth corridor (one of the fastest-growing suburban regions in the mid-Atlantic), and home of the Manassas National Battlefield Park and Prince William County's major exurban commercial district — draws its municipal water supply from the Occoquan Reservoir via the City of Manassas Water Division. Water hardness in Manassas measures 127.5 mg/L — classified as moderately hard.

Manassas' moderate hardness reflects the Bull Run watershed's Northern Virginia Triassic and Piedmont geology. The Occoquan Reservoir and Bull Run drain: the Triassic Culpeper Basin (Triassic Manassas Sandstone and Balls Bluff Siltstone — moderately calcareous calcareous Triassic red beds of the northern Virginia Newark-type basin); and the Northern Virginia Piedmont Province (Precambrian–Paleozoic calcareous-moderate granitic gneiss of the northern Virginia Blue Ridge–Piedmont transition). The PWCSA Occoquan treatment and the calcareous Triassic basin geology produce the moderate 127.5 mg/L.

At 127.5 mg/L, Manassas residents encounter moderate scale accumulation. Monthly cleaning with citric acid solution is recommended for faucet aerators and showerheads. City of Manassas Water Division consistently delivers water meeting all Virginia DEQ and EPA Safe Drinking Water Act requirements.