Fairfax County, Virginia: drinking water report. Fairfax County is the most populous jurisdiction in Virginia, home to about 1.15 million residents in the…
Fairfax County is the most populous jurisdiction in Virginia, home to about 1.15 million residents in the suburbs west and south of Washington, DC. Fairfax Water (formerly Fairfax County Water Authority) is the largest water utility in Virginia, serving over 2 million people across Fairfax County and parts of neighboring jurisdictions. The primary source is the Potomac River, supplemented by the Occoquan Reservoir – one of the first large-scale indirect potable reuse facilities in the United States.
The Potomac River receives treated wastewater effluent and stormwater from communities across a watershed that extends from West Virginia through Maryland and Virginia. Despite this, Fairfax Water has maintained a strong compliance and treatment record. The Occoquan system, which reclaims treated wastewater, puts it through advanced treatment before releasing it to the reservoir – a model that has operated successfully since 1978.
UCMR5 data shows low-level PFAS detections in the Fairfax Water system. According to the Virginia Department of Health's 2024 monitoring data, PFAS concentrations were below proposed federal MCLs. Fort Belvoir, an active Army installation in the southern part of the county, has documented AFFF use, and PFAS has been detected in monitoring wells on the installation.
Fairfax Water's treatment infrastructure is among the best in the mid-Atlantic region, but individual home plumbing still introduces variables.
Check your water to see data specific to your ZIP code. For general water quality maintenance, an activated carbon filter improves taste and reduces chlorine residuals. For PFAS, reverse osmosis provides stronger protection. Our water filter guide covers both. Pull your detailed report for historical data, and visit our Virginia page for statewide patterns.