Prince William County, Virginia: drinking water report. Prince William County in northern Virginia has a population of about 480,000, making it one of the…
Prince William County in northern Virginia has a population of about 480,000, making it one of the state's most populous jurisdictions. The Prince William County Service Authority draws water from the Occoquan Reservoir and Lake Manassas, serving a fast-growing suburban population in the Washington, D.C. metro area. Quantico Marine Corps Base occupies the county's eastern shoreline along the Potomac River, and the former military training activities there have left environmental signatures.
The Occoquan Reservoir is notable for being one of the first large-scale indirect potable reuse projects in the country – the Upper Occoquan Service Authority treats wastewater to near-drinking-water quality before discharging it into the reservoir, where it blends with stream flow and is further treated by the Fairfax County Water Authority. Prince William County purchases some of this water. According to the 2024 PWCSA water quality report, the system met all federal standards, but the source water's recycled component means treatment is intensive.
MCB Quantico has confirmed PFAS contamination from AFFF use. The EPA's UCMR5 data shows PFAS detections in Prince William County systems. A 2024 Virginia DEQ assessment documented PFAS in monitoring wells near Quantico at concentrations above 20 ppt for PFOS.
Prince William County's water undergoes extensive treatment, and the system performs well. But for residents near Quantico or on private wells in the eastern part of the county, PFAS from the base is a documented concern.
Check your water for current data at your address. For PFAS, reverse osmosis is the most effective household treatment. Our water filter guide explains which systems handle the contaminants found in this area. Pull your detailed report for trends, and visit our Virginia page for statewide context.