Frederick County, Maryland: drinking water report. Frederick County in western Maryland has a population of about 275,000.
Frederick County in western Maryland has a population of about 275,000. The City of Frederick draws from the Monocacy River and several reservoirs, while surrounding communities use a mix of municipal systems and private wells. The county sits atop a mix of limestone, sandstone, and metamorphic geology that produces varied groundwater chemistry. Fort Detrick – the U.S. Army's principal biological defense research facility – occupies 1,200 acres on the northwest edge of Frederick city.
Fort Detrick has a contamination history spanning seven decades. According to the Army's 2024 environmental report, the facility's Area B – used for biological agent testing and waste disposal – has documented contamination including TCE, other chlorinated solvents, and more recently PFAS from firefighting foam. The TCE plume has migrated off-base and affected private wells in the Rosemont neighborhood, leading to a long-running cleanup effort and community health concerns.
The EPA's UCMR5 data shows PFAS detections in Frederick's municipal system. According to the Maryland Department of the Environment's 2024 PFAS investigation, three monitoring wells near Fort Detrick showed PFOS at concentrations above 50 ppt. Frederick County's karst limestone geology allows rapid contaminant migration underground.
Fort Detrick's contamination has been a community issue for years, and residents near the base have reason to monitor their water actively. The Army has provided alternative water supplies for some affected properties, but coverage is not universal.
Check your water for current monitoring data. For TCE and PFAS, reverse osmosis handles both. Our water filter guide covers systems certified for military-related contaminants. Pull your detailed report for historical trends, and visit our Maryland page for statewide context.