Sussex County, Delaware: drinking water report. Sussex County is Delaware's largest and southernmost county, with about 237,000 residents that swell…
Sussex County is Delaware's largest and southernmost county, with about 237,000 residents that swell significantly during beach season. Rehoboth Beach, Lewes, and Georgetown are the main communities. The county sits on the Delmarva Peninsula's flat coastal plain, drawing water entirely from groundwater – the Columbia Aquifer and deeper formations. The county's poultry industry is among the densest in the nation, with over 1,000 poultry houses generating waste that is applied to surrounding farmland.
Nitrate contamination from poultry litter is the primary groundwater quality issue in Sussex County. According to Delaware DNREC's 2024 groundwater monitoring data, 26% of private wells tested in the county's agricultural zones exceeded the nitrate MCL of 10 mg/L. The sandy, porous soils of the coastal plain provide almost no barrier between the land surface and the aquifer.
The former Fort Miles military installation near Lewes used AFFF during WWII-era operations. A 2024 DNREC investigation found PFAS at 14 ppt in monitoring wells near the former base area. Saltwater intrusion also threatens coastal wells – chloride concentrations have been rising in barrier island production wells as pumping increases during tourist season.
Sussex County's flat, sandy geology means everything applied to the land surface eventually reaches the aquifer. With the density of poultry operations here, nitrate contamination in private wells is a probability, not a possibility.
Check your water for data at your address. Reverse osmosis handles nitrate, PFAS, and elevated minerals from saltwater intrusion in a single system. Our water filter guide covers options for coastal plain groundwater. Pull your detailed report for trends, and visit our Delaware page for statewide patterns.
Drinking water is one exposure route. These federal datasets also cover Sussex County, DE.
The EPA places Sussex County, DE in Zone 3 - the EPA's lowest-risk category, with a predicted average indoor radon level below 2 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.
25% of homes in Sussex County, DE were built before 1980, and 6% 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 Sussex County, DE averages 6.6 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