waterbycounty
Compiled federal source snapshot

South Carolina Water Quality

Drinking water data for all 46 counties.

Avg SDWIS Compliance Index

68.0

Most Common Five-Year SDWIS Compliance Band

A

Counties with Data

46

of 46 total

County water atlas

South Carolina water signals by county

A state-level 2.5D view across drinking-water compliance, watershed impairment, monitoring density, and streamflow snapshot context. Pin any county, switch layers, then use the lens controls to compare index ranges, recorded violation rates, or impaired watersheds without leaving the page.

Counties

46

Avg SDWIS index

68.0

Watersheds

32

ATTAINS counties

Monitoring

46

33 fresh USGS snapshots

State atlas layers combine EPA SDWIS health-based violations, EPA ATTAINS 303(d) impairment assessments, EPA Water Quality Portal monitoring sites, and representative USGS NWIS streamflow gauges. Streamflow values appear only for fresh pipeline snapshots, not as a continuously updated stream. County pages include the observation time and year.

Prepared by ByCounty Editorial TeamPublished by WaterByCounty

Multi-source coverage in South Carolina

Beyond Drinking Water

EPA SDWIS

46/ 46

counties with drinking-water compliance data

126 health violations statewide (5yr)

EPA ATTAINS

59.9%

avg impaired across 32 counties

34 of 50 assessed bodies impaired

EPA WQP

1,453

monitoring sites across 46 counties

416,392 total readings (5yr window)

USGS NWIS

33

counties with a fresh pipeline snapshot

0 above33 below

State atlas notes

What stands out in South Carolina

County water quality is not one number. The strongest read comes from comparing drinking-water compliance against watershed impairment, monitoring density, and streamflow context. Use these signals as a starting point, then open any county profile for source-level detail.

Compliance spread

Allendale County has the highest value in the published state SDWIS Compliance Index table at 86.2/100, while McCormick County has the lowest at 16.4/100. That is a 69.8 point gap inside one state.

Zero health violations

19

3+ health violations

15

Watershed pressure

The atlas impairment layer points to counties where assessed water bodies are most likely to miss state quality standards. Assessment density varies, so compare the percentage with the number of assessed bodies on the county page.

Aiken County100.0%Bamberg County100.0%Barnwell County100.0%

Monitoring hubs

Charleston County138 sitesBeaufort County132 sitesHorry County106 sites

Lowest flow reads

Berkeley County2%Williamsburg County3%Georgetown County5%

Highest fresh streamflow pipeline snapshots: Horry County (86%, observation 2026), Cherokee County (75%, observation 2026), Spartanburg County (75%, observation 2026). These are source-data observations, not household tap-water conclusions.

All South Carolina Counties

CountySDWIS Compliance Index
Allendale County86.2
Barnwell County86.2
Calhoun County86.2
Chester County86.2
Clarendon County86.2
Darlington County86.2
Dillon County86.2
Edgefield County86.2
Florence County86.2
Greenville County86.2
Hampton County86.2
Jasper County86.2
Kershaw County86.2
Lancaster County86.2
Lee County86.2
Marion County86.2
Marlboro County86.2
Orangeburg County86.2
Spartanburg County86.2
Anderson County71.2
Horry County71.2
Dorchester County70.7
Pickens County69.8
Oconee County69.0
Laurens County67.4
Charleston County66.5
Greenwood County66.5
Aiken County65.6
Beaufort County65.1
Sumter County65.1
Richland County64.5
York County59.6
Fairfield County58.6
Berkeley County58.3
Cherokee County57.3
Georgetown County57.3
Colleton County56.9
Lexington County52.5
Newberry County52.3
Bamberg County46.2
Williamsburg County42.1
Chesterfield County40.3
Saluda County31.1
Abbeville County27.8
Union County19.6
McCormick County16.4

Frequently Asked Questions

Which South Carolina county has the highest SDWIS Compliance Index?
Allendale County has the highest SDWIS Compliance Index in the published South Carolina cohort at 86.2/100. This WaterByCounty relative comparison is not an EPA score and does not establish current conditions for a utility or address.
What does the Five-Year SDWIS Compliance Band mean?
The band is derived only from each county aggregation's recorded health-violation rate per 100,000 people served for the stated five-year source window. It is separate from the relative SDWIS Compliance Index and is not a current determination for a specific utility or address.
What does EPA ATTAINS report across South Carolina?
Across 32 published South Carolina county records with EPA ATTAINS data, 34 of 50 assessed water bodies are listed as impaired. This is a watershed assessment and does not describe finished household tap water.
Which USGS streamflow records are shown across South Carolina?
WaterByCounty has 33 fresh USGS pipeline snapshots in the published South Carolina cohort. Each county page shows its observation timestamp and year. A pipeline snapshot is not a continuously updated reading or a tap-water safety measure.
Where can South Carolina residents find current official information?
Review the applicable utility's Consumer Confidence Report, active notices, and the state drinking-water agency. WaterByCounty's county-level historical aggregations do not establish the current status of a specific utility, address, private well, or household plumbing system.
What does Water Quality Portal monitoring volume show in South Carolina?
The published county records contain 416,392 results from 1,453 monitoring locations in the site's five-year aggregation. Monitoring volume does not by itself indicate better or worse water quality.

Data Sources

Drinking-water compliance data from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. The WaterByCounty SDWIS Compliance Index reflects the recorded rate and is not an EPA score.

Disclaimer: This data is informational only. It is not health, legal, or professional advice. For concerns about your specific water supply, contact your local water utility.

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