Tysons Water Hardness & Quality Report (2026)

Fairfax Water serves Tysons in Fairfax County, Virginia, supplying over 1.4 million people across Northern Virginia. Primary sources are the Potomac River, drawn via the Washington Aqueduct and supplemented by Fairfax Water's own intake, and the Occoquan Reservoir. Treatment occurs at the Frederick P. Griffith Jr. Treatment Plant handling the Potomac source and the Corbalis Treatment Plant handling the Occoquan source, employing coagulation, sedimentation, filtration, and chloramination. The service area includes Fairfax County and parts of Prince William, Loudoun, and Arlington Counties, served through over 1,500 miles of distribution pipe.

The Potomac River watershed spans 14,670 square miles across four states and Washington D.C., draining the Appalachian Plateau to the Coastal Plain. Underlying geology features Catoctin Formation greenstone (late Precambrian metavolcanics) and Loudoun Formation conglomerates in the upper basin, transitioning to Potomac Group sands and clays downstream. The Occoquan Reservoir lies within the Fall Zone over metavolcanic and metasedimentary rocks. This Piedmont terrain — dominated by gneiss, schist, and granite from the Grenville orogeny — imparts a moderately mineralised character through silicate weathering and minor carbonate presence, without karst limestone dominance.

At moderately hard levels, limescale buildup develops in kettles, coffee makers, dishwashers, and water heaters, reducing efficiency and lifespan. Faucet aerators and showerheads may clog, and laundry may feel less clean from soap scum. Monthly vinegar descaling, installing sediment filters, and using detergent boosters help maintain appliances. A water softener is recommended for households noticing spots on glassware or dry skin. Fairfax Water maintains pH 7.5–8.5 with full lead/copper rule compliance; the 2024 Consumer Confidence Report shows all primary contaminants below MCLs, including TTHMs at 45 µg/L avg and haloacetic acids at 30 µg/L avg, with PFAS monitoring detecting PFOA/PFOS below health advisories.