Free Maryland water report: PFAS & lead levels for every water system, worst-affected cities, and EPA violations. Check your ZIP.
Maryland's drinking water serves approximately 6.2 million residents across a geographically compact but ecologically diverse state. The Chesapeake Bay dominates the landscape, and its watershed influences water quality across most of the state. Water sources range from the Potomac River (which supplies much of the DC suburbs in Montgomery and Prince George's counties), to the Liberty and Loch Raven reservoirs (supplying Baltimore), to groundwater wells on the Eastern Shore and in Western Maryland's Appalachian ridge-and-valley terrain. The Maryland Department of the Environment (MDE) regulates about 3,800 public water systems, from the Washington Suburban Sanitary Commission (WSSC) serving nearly 1.9 million people to tiny community wells in rural areas.
Maryland's position between the industrial Mid-Atlantic and the agricultural Eastern Shore means its water faces contamination from both directions: upstream industrial and urban discharges in the Potomac and Susquehanna watersheds, and agricultural runoff from poultry operations and row crops on the Delmarva Peninsula.
PFAS monitoring in Maryland has accelerated since 2020, driven by both UCMR5 requirements and state-level investigations around military installations. The state's most significant PFAS contamination site is Aberdeen Proving Ground in Harford County – a massive Army testing facility that has been in operation since 1917 and is already a Superfund site for other contaminants.
Aberdeen Proving Ground's firefighting training areas, munitions testing grounds, and industrial operations have used PFAS-containing materials for decades. PFAS has been detected in groundwater on and around the installation, and the Army is conducting ongoing investigation under CERCLA (Superfund) authority. Other military-connected sites, including Fort Meade (home to the NSA) and Andrews Air Force Base in Prince George's County, have also shown PFAS detections in surrounding monitoring.
Maryland adopted a PFAS drinking water standard of 10 ppt for the sum of PFOA and PFOS in 2024, placing it among the stricter states nationally. MDE has also required all community water systems to conduct PFAS monitoring, going beyond the federal UCMR5 scope.
The Potomac River, which supplies water to much of suburban Maryland and all of Washington, DC, carries PFAS from upstream sources in West Virginia, Virginia, and the DC metro wastewater infrastructure. WSSC's treatment plants use conventional processes that provide limited PFAS removal.
Among Mid-Atlantic states, Maryland is taking a more proactive regulatory approach than Virginia but trails New Jersey's aggressive standards and remediation programs. Pennsylvania is still finalizing its PFAS MCLs. Delaware, sharing the Delmarva Peninsula, faces similar agricultural contamination pathways but with even less treatment capacity.
Maryland's Chesapeake Bay restoration efforts – the largest estuary recovery program in the country – have dominated environmental policy for decades. PFAS adds a new dimension: the compounds are persistent in the bay's ecosystem, accumulating in fish and shellfish. The Chesapeake Bay Program, a federal-state partnership, has begun incorporating PFAS into its monitoring framework.
Aberdeen Proving Ground's contamination history extends far beyond PFAS. The facility has tested chemical weapons, munitions, and industrial compounds for over a century, and the existing Superfund cleanup is one of the most complex in the country. PFAS is the latest in a long line of contaminants associated with the installation.
Maryland's water quality varies by region: the DC suburbs face different issues than Baltimore, the Eastern Shore, or Western Maryland.
1. Check your location at the homepage. We show PFAS and other contaminant data mapped to your ZIP code. 2. Residents near Aberdeen Proving Ground, Fort Meade, or Andrews AFB should verify that their water system has been tested for PFAS and review the results. Private well owners within several miles of these installations should pursue independent testing. 3. Eastern Shore residents on groundwater should be aware that agricultural chemicals (nitrate, pesticides) may be present alongside any PFAS contamination. Comprehensive well testing is recommended. 4. Our water filter guide covers options for PFAS, lead, and disinfection byproducts. A detailed water report provides historical trends for your address.
Maryland's water infrastructure reflects the state's role as a border between the industrial North and the agricultural South. Baltimore's reservoir system dates to the mid-19th century, with the Gunpowder Falls watershed providing the city's primary supply through three reservoirs: Loch Raven, Prettyboy, and Liberty. The system has been well maintained but faces challenges from suburban development encroaching on watershed lands.
The Potomac River has improved dramatically since the 1960s and 1970s, when it was notoriously polluted. The Blue Plains Advanced Wastewater Treatment Plant – the largest in the world, operated by DC Water – treats over 300 million gallons per day of sewage from DC, Maryland, and Virginia before discharging to the Potomac. Upgrades over the decades have reduced nutrient and pathogen loads, but emerging contaminants like PFAS and pharmaceuticals pass through conventional treatment.
Aberdeen Proving Ground's environmental legacy is among the most complex in the DoD portfolio. The facility encompasses over 72,000 acres and includes the Edgewood area – where chemical agents were manufactured and tested – and the Aberdeen area, focused on ordnance testing. Groundwater contamination from decades of operations extends off-installation, and the PFAS investigation adds another layer to an already multi-decade cleanup effort.
The Chesapeake Bay cleanup, formally launched with the 1983 Chesapeake Bay Agreement and renewed multiple times since, has been the defining environmental initiative in Maryland for 40 years. Progress on reducing nitrogen and phosphorus from agriculture, wastewater, and urban runoff has been measurable but insufficient to meet all restoration targets. PFAS contamination in the bay ecosystem is a newer concern, with studies showing accumulation in blue crabs, rockfish (striped bass), and other commercially important species.
Maryland's 2024 adoption of a 10 ppt combined PFAS standard signals that the state is taking the contamination seriously. Implementation, however, requires treatment upgrades at dozens of water systems – a capital investment that will play out over years.
Check your address to see current data for your area. In a state where military installations, agricultural operations, and urban infrastructure all contribute to water quality, your specific location determines your exposure.