Lincolnia Water Hardness & Quality Report (2026)

Lincolnia, Virginia, in Fairfax County in central Fairfax near Bailey's Crossroads and Annandale — an unincorporated community in the dense inner Fairfax County residential and commercial corridor between Alexandria and Tysons Corner — receives its municipal water from Fairfax Water, which draws from two primary sources: the Occoquan Reservoir (fed by Bull Run and Occoquan Creek) and the Potomac River at the Griffith Water Treatment Plant in Great Falls. Fairfax Water blends these two sources across its service zone based on demand and seasonal availability.

The moderately hard 165 mg/L hardness and TDS of 388.2 mg/L reflect Lincolnia's central Fairfax distribution zone blend, which is harder than communities receiving predominantly Occoquan supply (Baileys Crossroads 112 mg/L, Fairfax City 105 mg/L) but softer than communities receiving predominantly Potomac supply (Chantilly 183.5 mg/L). The Occoquan Reservoir drains the Northern Virginia Piedmont — Precambrian metamorphic rocks (Chopawamsic terrane schists and gneisses) with minimal carbonate — producing soft base water. The Potomac River at Griffith carries carbonate hardness from the Shenandoah Valley and Valley and Ridge Province tributaries (Ordovician and Cambrian carbonate formations), adding harder content to the blend. Lincolnia's intermediate hardness reflects Fairfax Water's central service zone blend ratio.

At 165 mg/L, Lincolnia residents experience moderately hard water — harder than most inner Fairfax communities. Scale builds in kettles and coffee machines within weeks to months, dishwashers benefit from rinse aid, and bathroom fixtures develop calcium deposits. Quarterly descaling of heating appliances is the standard schedule. The elevated PFAS level of 8.5 ppt warrants a certified drinking water filter with urgency — Lincolnia's position in the densely developed inner Fairfax corridor, proximate to Andrews Air Force Base drainage, Fort Belvoir (one of Virginia's most significant PFAS contributors), and the dense Northern Virginia defense contractor community, results in elevated PFAS for this central Fairfax service zone.