Baltimore County, Maryland: drinking water report. Baltimore County surrounds Baltimore City on three sides and contains a mix of suburban communities…
Baltimore County surrounds Baltimore City on three sides and contains a mix of suburban communities including Towson, Dundalk, Catonsville, Essex, and Owings Mills. The county relies on both Baltimore City's Montebello and Ashburton reservoirs (drawing from the Susquehanna River system) as well as local Liberty Reservoir sources. About 1.8 million residents across the metropolitan area share this interconnected water supply, with Baltimore County Department of Environmental Protection and Sustainability managing local distribution.
Maryland drinking water faces elevated scrutiny following PFAS detections across the state's major metropolitan areas. Baltimore County falls within the Chesapeake Bay watershed, where agricultural runoff, legacy industrial sites, and urban stormwater all influence source water quality. EPA's UCMR5 sampling detected PFAS compounds in multiple Baltimore metro utilities between 2023 and 2024, though specific concentrations vary by distribution zone and distance from treatment facilities.
The county's aging infrastructure presents lead concerns similar to other mid-Atlantic jurisdictions with housing stock from the 1940s through 1970s. Baltimore County utilities have conducted lead and copper rule sampling that shows the typical pattern: homes with service lines or indoor plumbing installed before 1986 face higher risk, particularly in neighborhoods with original brass fixtures. While recent samples generally stay below the 15 ppb action level at the 90th percentile, individual homes still test above that threshold during routine monitoring.
Chlorination byproducts (trihalomethanes and haloacetic acids) remain a persistent challenge for systems drawing from surface reservoirs. Warm months increase organic matter breakdown in Liberty Reservoir and the Loch Raven system, which can push disinfection byproduct levels higher even when utilities remain in compliance. Nitrate levels stay well below federal limits, though localized agricultural areas in the county's northern reaches occasionally show elevated readings in private wells that don't serve the main public system.
Test your tap water if your home was built before 1990 or you live near former industrial zones along the Patapsco River corridor or old rail lines. Consider point-of-use filtration for PFAS reduction if you fall into sensitive populations (pregnant women, infants, immunocompromised individuals). Check your water to see current contaminant data for your specific address, review our water filter guide to match filtration technology to your exposure risks, and read the detailed report for full testing methodology. Visit the Maryland state page for broader context on Chesapeake watershed challenges and statewide PFAS response efforts.
Drinking water is one exposure route. These federal datasets also cover Baltimore County, MD.
The EPA places Baltimore County, MD in Zone 1 - the EPA's highest-risk category, where the predicted average indoor radon level is above 4 pCi/L. Zone maps predict an area's radon potential from geology and existing indoor readings; they say nothing about a specific house. Testing is the only way to know your own level.
60% of homes in Baltimore County, MD were built before 1980, and 15% before 1950. Residential lead paint was banned in 1978, so housing age is the strongest available proxy for lead-paint exposure. This describes the county's housing stock, not any one home.
Modelled annual fine-particle pollution (PM2.5) in Baltimore County, MD averages 7.3 µg/m³, within the EPA's annual standard of 9 µg/m³. These are CDC modelled county estimates rather than readings from a specific monitor.
How radon zones work · Air quality by county · Lead exposure guide