Alexandria Water Hardness & Quality Report (2026)

Virginia American Water, Alexandria District serves the City of Alexandria and adjacent areas of Fairfax and Arlington Counties, Virginia. It operates as a consecutive system purchasing treated water from Fairfax Water's two surface plants: the J.J. Corbalis plant on the Potomac River in Fairfax County and the Griffith plant on the Occoquan Reservoir in Prince William County. These facilities draw from major regional surface water bodies to supply over 1.7 million people across Northern Virginia.

The Potomac River watershed spans 14,670 square miles across four states and D.C., with headwaters in the Appalachian Mountains draining through the Piedmont and Coastal Plain to the Chesapeake Bay. The Occoquan Reservoir, impounded in 1952, collects drainage from 593 square miles of forested and suburban Piedmont terrain. Local geology features Catoctin greenstone, Loudoun Formation quartzites, and Chickahominy paleochannel sands, with no major limestone aquifers. This bedrock weathers to yield a moderately mineralised supply rich in dissolved calcium and magnesium from silicate minerals, producing moderate hardness.

Moderate hardness promotes limescale buildup in pipes, heaters, and fixtures, shortening the lifespan of water heaters by 30–50% and reducing efficiency in dishwashers and washing machines. Soap lathering diminishes, increasing detergent use by 50%. Installing scale-inhibiting filters or softeners provides protection; regular vinegar descaling helps kettles and showerheads. pH averages 7.6, within optimal range. The system complies with the Lead and Copper Rule with no action level exceedances; disinfection byproducts and trihalomethanes meet standards via Fairfax Water's coagulation, sedimentation, filtration, and chloramination treatment.