Free Delaware water report: PFAS & lead levels for every water system, worst-affected cities, and EPA violations. Check your ZIP.
Delaware is the second-smallest state by area but packs approximately 1.0 million residents into a narrow strip of land between the Delaware Bay and the Maryland border. The state's water supply splits sharply along geographic lines: northern Delaware (New Castle County) draws primarily from surface water – the Brandywine Creek, White Clay Creek, and other tributaries feeding into reservoirs – while southern Delaware (Kent and Sussex Counties) depends almost entirely on groundwater from the Coastal Plain aquifer system.
The Delaware Department of Natural Resources and Environmental Control (DNREC) and the Division of Public Health (DPH) jointly oversee drinking water quality for about 400 public water systems. The groundwater dependence of the southern half of the state makes it particularly vulnerable to contamination that reaches the water table. Sussex County, Delaware's most agricultural county, faces a combination of farm runoff contamination and proximity to Dover Air Force Base's contamination plume.
Delaware's small size means that contamination at a single site can affect a disproportionate share of the state's population and water resources. There is not much buffer between point sources and drinking water supplies.
The EPA's UCMR5 monitoring has confirmed PFAS detections at public water systems in Delaware, with the strongest signals in areas near military installations and industrial facilities. The state's groundwater dependence in the south means that PFAS reaching the water table has a direct pathway to drinking water wells.
Delaware has been developing state-specific PFAS standards. DNREC established a groundwater quality standard for PFOA and PFOS at 70 ppt (combined) and has been working toward drinking water MCLs that will apply to public water systems. The state is evaluating whether to adopt standards stricter than the 2024 federal MCLs of 4 ppt for PFOA and PFOS individually.
The contamination picture in Delaware is concentrated but significant. The central part of the state, around Dover, shows the highest PFAS readings in monitoring data, driven primarily by military contamination. Northern Delaware, with its surface water supply and greater distance from military PFAS sources, generally shows lower levels.
Dover Air Force Base is the dominant PFAS contamination source in Delaware. Located adjacent to the state capital, the base has confirmed PFAS in groundwater from decades of AFFF use in firefighting training. The contamination plume extends beyond the base boundaries into surrounding communities in Kent County.
The Air Force has conducted extensive monitoring around Dover AFB and has provided alternative water supplies to affected properties with private wells showing elevated PFAS. Remediation efforts are underway, but the timeline for full cleanup is measured in years to decades. The base is one of the Air Force's major airlift hubs, meaning it has had decades of high-volume AFFF use associated with large aircraft operations.
Delaware's Air National Guard facilities have also been examined for PFAS contamination, consistent with the Department of Defense's nationwide assessment. The New Castle Air National Guard Base, located at the Wilmington airport, is included in this review.
For a small state, the impact of a single major military PFAS source like Dover AFB is outsized. The contamination affects the same aquifer that provides drinking water to a significant portion of Kent County's population. See our military bases page for current investigation status.
Delaware has taken a measured but increasingly active approach to PFAS regulation. DNREC has established groundwater quality standards and is working toward drinking water MCLs. The state has also conducted PFAS investigations at potential source sites including landfills, industrial facilities, and firefighting training areas beyond military bases.
Under UCMR5, Delaware's public water systems were required to test for 29 PFAS compounds. Results have confirmed the geographic pattern: systems in central Delaware near Dover AFB show the most significant detections, while systems in northern Delaware generally show lower levels.
According to DNREC's data, approximately 30% of Delaware residents – concentrated in Kent and Sussex Counties – rely on private wells. These wells are not subject to PFAS testing requirements, but DNREC and DPH have recommended testing for homeowners near known contamination sources. The state has offered limited free testing programs in areas around Dover AFB.
Delaware's small size has allowed regulators to be more hands-on than in larger states. DNREC's PFAS coordinator works directly with affected communities, and the state's tight geography means investigation and response can move faster than in states where contamination sites are hundreds of miles apart.
For a primer on PFAS compounds and health research, see our PFAS guide.
Delaware's split between surface water in the north and groundwater in the south creates two different risk profiles. Residents in Kent and Sussex Counties – particularly those on private wells – face more direct PFAS exposure pathways.
1. Check your ZIP code at the homepage to see monitoring data for your specific water system. We compile UCMR5, DNREC, and utility data in one place. 2. If you are on a private well in Kent County near Dover AFB, testing for PFAS is strongly recommended. Contact DNREC to see if free or subsidized testing is available in your area, or use a certified lab ($200-400). 3. For confirmed PFAS contamination, reverse osmosis is the most effective household treatment. Our water filter guide covers which systems are certified for PFAS removal and how they compare. 4. Request a detailed water report for your address to see how your area's data compares to state and federal thresholds.
Delaware may be small, but its PFAS challenges are concentrated and consequential. Check your specific location to see where you stand.