South Carolina Private Well Water Risk: Arsenic & Nitrate

These figures are USGS statistical estimates for private (domestic) wells in South Carolina. They describe the area's modeled risk — not any single well.

This is a modeled probability for the area, not a measurement of your well. USGS statistical models estimate how many private wells in this area are likely to exceed the federal limit — they cannot tell you what is in your water. Two neighbors can have very different results. The only way to know your well is to test it.

Nitrate

0.1%

of the private-well population is modeled above the 10 mg/L nitrate limit

~563

people on wells estimated above the limit

~876,000

total residents on private wells statewide

Source: USGS machine-learning nitrate model, Ransom et al. (2022), domestic-well depth zone.

Arsenic

Across South Carolina, an estimated ~28,133 people rely on private wells with modeled arsenic above the 10 µg/L EPA limit. The highest modeled exposure is in York County (~6,446 people).

Counties with the highest modeled arsenic exposure

CountyEst. well residents over arsenic limit90% range
York County~6,4463,75510,693
Florence County~2,3171,5533,399
Berkeley County~2,1501,5053,099
Horry County~2,1061,4683,023
Charleston County~1,7431,1502,640
Lexington County~1,4111,0361,936
Colleton County~9636231,481
Richland County~8546611,113
Chester County~8275731,204
Jasper County~7875261,171
Sumter County~7875351,144
Williamsburg County~612424877
Clarendon County~605405897
Dorchester County~462336641
Darlington County~439299633
Anderson County~409296567
Orangeburg County~405298556
Lancaster County~402241717
Aiken County~359258501
Hampton County~342218531
Newberry County~299213417
Greenwood County~284185438
Spartanburg County~283196416
Greenville County~274188415
Laurens County~207143304
Beaufort County~195127296
Chesterfield County~191136267
Barnwell County~176120259
Lee County~174121247
Calhoun County~162120218
Bamberg County~153108218
Pickens County~146105205
Oconee County~13798199
Abbeville County~13392194
Marlboro County~12294159
Marion County~11277162
Saluda County~10582136

9 additional South Carolina counties have lower modeled arsenic exposure (fewer than 100 estimated well residents over the limit).

Source: USGS domestic-well arsenic model, Lombard et al. (2021); county population product (2017).

Treating arsenic in South Carolina

Arsenic is not removed by carbon pitchers or faucet filters. Reverse osmosis is the treatment that brings it below the federal limit at your tap.

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