Sumter County, South Carolina: drinking water report. Sumter County in central South Carolina has about 107,000 residents, with the City of Sumter as the…
Sumter County in central South Carolina has about 107,000 residents, with the City of Sumter as the county seat. Water comes from the Middendorf and Black Creek aquifers – deep, confined groundwater sources. Shaw Air Force Base (now part of Joint Base Charleston-Shaw) occupies a large area east of the city. The county's agricultural economy includes poultry, timber, and row crops.
Shaw AFB has confirmed PFAS contamination from AFFF firefighting foam. According to the Air Force's 2024 environmental investigation, PFOS concentrations in monitoring wells near the fire training areas exceeded 80 ppt. The contamination plume extends off-base toward residential areas east of Sumter. South Carolina DHEC's 2024 investigation found PFAS in private wells within one mile of the base at concentrations up to 35 ppt.
The deep confined aquifers that supply Sumter's municipal system are generally well-protected from surface contamination, but the Shaw AFB plume is migrating through the intermediate aquifer zones. A 2024 DHEC assessment noted that one municipal monitoring well showed the first detectable PFAS – at 3 ppt – suggesting the plume is beginning to reach deeper zones.
Sumter residents near Shaw AFB face the most immediate exposure risk, particularly those on private wells. The Air Force has been sampling residential wells, but if you live near the base and have not been contacted, request testing through the base's environmental program.
Check your water for available data. For PFAS, reverse osmosis is the most effective household treatment. Our water filter guide identifies systems with the highest certified PFAS removal. Get your detailed report for local data, and visit our South Carolina page for statewide context.
Drinking water is one exposure route. These federal datasets also cover Sumter County, SC.
The EPA places Sumter County, SC 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.
38% of homes in Sumter County, SC 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 Sumter County, SC averages 7.8 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