South Dakota Water Quality
Drinking water data for all 66 counties.
Avg Water Score
56.8
State Grade
D
Counties with Data
63
of 66 total
All South Dakota Counties
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Frequently Asked Questions
Which county in South Dakota has the best water quality?
Aurora County has the highest water quality score in South Dakota at 86.0/100 (Grade: A), based on EPA SDWIS data.
Which county in South Dakota has the most water violations?
Roberts County has among the lowest water quality scores in South Dakota at 10.6/100. See the individual county page for detailed violation history.
Is the tap water safe to drink in South Dakota?
South Dakota has an average water quality score of 56.8/100 based on EPA Safe Drinking Water Act compliance data. Individual county scores vary — check your specific county's page for detailed information.
What contaminants are found in South Dakota water supplies?
Drinking water quality varies by county and water system. The EPA Safe Drinking Water Information System (SDWIS) tracks violations for contaminants like lead, nitrates, bacteria, and disinfection byproducts. See individual county pages for specific contaminant and violation history.
Data Source
Water quality data sourced from the EPA Safe Drinking Water Information System (SDWIS) via the ECHO enforcement database. Scores reflect compliance history and health-based violation counts.
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.