County · South Dakota
Union County, South Dakota: drinking water records
This overview covers 4 ZIP codes and 9 community water systems in Union County. It also stands in for 0 ZIP codes whose utility has too little EPA data for a page of its own.
System population figures are summed from EPA registry records and can overlap where wholesalers and retail systems serve the same people. They are not a Census county-population estimate.
Water systems with the most complete records
| Water system | People served | PFAS survey results | PFAS found | Health-based violations | Lead, 9 in 10 homes at or below |
|---|---|---|---|---|---|
| South Lincoln Rural Water System SD4600870 | 5,250 | 120 | 0 | 0 | 1 ppb |
| Clay Rural Water System SD4600626 | 4,780 | 60 | 0 | 0 | 1 ppb |
| Dakota Dunes Cid SD4602093 | 3,700 | 0 | 0 | 0 | 4 ppb |
| North Sioux City SD4600226 | 3,042 | 0 | 0 | 0 | 4 ppb |
| Beresford SD4600386 | 2,359 | 0 | 0 | 0 | 4 ppb |
| Elk Point SD4600116 | 2,124 | 0 | 0 | 0 | 2 ppb |
| Clay Rws/South Union SD4602185 | 1,447 | 0 | 0 | 0 | 1 ppb |
| Alcester SD4600004 | 820 | 0 | 0 | 0 | 1 ppb |
| Jefferson SD4600060 | 475 | 0 | 0 | 0 | 1 ppb |
ZIP reports in Union County
No ZIP report in this county is published yet.
Sources and scope
EPA UCMR 5 occurrence data, samples collected 2023-01-03 – 2026-06-17, final release, August 2026 (file dated Aug 28, 2026); EPA SDWIS via ECHO, 2026Q2 extract (file dated Jul 9, 2026); EPA service-area boundaries v3.0; Census 2020 ZCTAs. Page generated 2026-09-03.
Counts cover the systems that report this county to EPA. A water system may cross county lines. "Found" means at least one result at or above the laboratory reporting level; it is not a compliance finding.