Woodlawn Water Hardness & Quality Report (2026)

Woodlawn, Virginia, in Fairfax County — an unincorporated Fairfax County community in the southeastern Fairfax corridor adjacent to Fort Belvoir and Mount Vernon, home of the Woodlawn Plantation (a National Trust for Historic Preservation site built for George Washington's niece) — receives its municipal water from Fairfax Water, which draws from the Occoquan Reservoir (the primary Fairfax Water surface water source) and the Potomac River (at the Griffith Water Treatment Plant). Fairfax Water serves the majority of Fairfax County through its two treatment facilities.

The moderately hard 123.5 mg/L hardness and TDS of 240 mg/L reflect Fairfax Water's Occoquan-Potomac blended supply character. The Occoquan Reservoir (on the Occoquan River and its tributaries — Bull Run, Cedar Run) drains the Virginia Piedmont including the Bull Run Mountains and the Triassic Culpeper Basin fringe — mixed Precambrian metavolcanic terrain and Triassic calcareous redbeds (the Balls Bluff Siltstone and Manassas Sandstone). The Triassic calcareous redbeds contribute moderate dissolved calcium and bicarbonate to the Occoquan system, while the Potomac River brings its mixed Blue Ridge-Valley and Ridge geological signature. The finished blended supply produces consistently moderate hardness throughout Fairfax County.

At 123.5 mg/L, Woodlawn's water is moderately hard — scale builds in kettles and appliances over months, dishwashers benefit from rinse aid, and faucet aerators need periodic cleaning. Quarterly descaling is appropriate. The PFAS level of 6.3 ppt warrants a certified drinking water filter — Fort Belvoir (US Army Training and Doctrine Command — a major AFFF user directly adjacent to Woodlawn), the Quantico Marine Corps Base in the Occoquan-Potomac watershed, and the dense Northern Virginia military-defense complex all contribute to Fairfax County's PFAS readings in this corridor.