Centreville Water Hardness & Quality Report (2026)

Centreville, Virginia, an unincorporated community in Fairfax County in Northern Virginia — a major suburban community and important Civil War battlefield site — draws its municipal water supply from the Occoquan Reservoir (on Bull Run in Prince William County) via Fairfax Water, which treats Occoquan Reservoir water at the Corbalis Water Treatment Plant and distributes throughout Fairfax County. Centreville is in the western Fairfax County Fairfax Water service zone. Water hardness in Centreville measures 178.5 mg/L — classified as hard.

Centreville's moderately hard supply reflects the Bull Run–Occoquan watershed's geology in Fairfax and Prince William Counties. The Occoquan watershed drains: the Northern Virginia Piedmont crystalline basement — the Precambrian Chopawamsic Formation (volcanic arc metavolcanic rocks — calcium-poor) and Quantico Formation (Cambrian–Ordovician phyllite and quartzite); portions of the Blue Ridge Front and the Valley and Ridge Paleozoic calcareous formations in the upper Bull Run headwaters (Devonian and Silurian limestone and shale of the northern Shenandoah Valley contribute moderate dissolved calcium). The 178.5 mg/L reflects a moderate calcareous input from the western Blue Ridge and Valley and Ridge drainage portions of the Occoquan watershed, blended with the predominantly soft Piedmont crystalline terrain.

At 178.5 mg/L, Centreville residents face regular hard water challenges. Scale deposits form on faucet aerators, showerheads, and appliances within weeks — monthly descaling with citric acid solution is standard maintenance. Fairfax Water consistently delivers water meeting all Virginia DEQ and EPA Safe Drinking Water Act requirements.