South Dakota Water Quality Report: 379 Violations Across 392 ZIPs
478 water systems · 392 ZIP codes · 379 violations · Updated 2026-05-31
Data: EPA Safe Drinking Water Information System (SDWIS), EPA ECHO Last verified: 2026-05-31
City Water Quality Map: South Dakota
Each circle represents a city. Size indicates population, color indicates water quality grade. Tap a circle for details.
Violation Trend
EPA violations across all water systems in South Dakota.
Cities with Most Violations in South Dakota
| # | City | Grade | Violations | Systems | Population | |
|---|---|---|---|---|---|---|
| 1 | Sioux Falls | C | 40 | 5 | 223,087 | Details → |
| 2 | Henry | C | 19 | 1 | 256 | Details → |
| 3 | Edgemont | B | 17 | 2 | 750 | Details → |
| 4 | Aberdeen | C | 16 | 5 | 50,402 | Details → |
| 5 | Carpenter | D | 10 | 2 | 217 | Details → |
| 6 | Morristown | C | 10 | 1 | 47 | Details → |
| 7 | Rosholt | C | 9 | 2 | 487 | Details → |
| 8 | Buffalo Gap | B | 9 | 1 | 126 | Details → |
| 9 | Lesterville | C | 9 | 1 | 115 | Details → |
| 10 | Tolstoy | C | 9 | 1 | 36 | Details → |
Most Common Contaminants in South Dakota
| Contaminant | Category | Violations | ZIPs Affected | Health Risk |
|---|---|---|---|---|
| Revised Total Coliform Rule | Microbiological | 97 | 65 | No |
| Chlorine residual | Disinfectant | 57 | 52 | Yes |
| Stage 1 DBP Rule | Treatment Technique | 27 | 25 | No |
| Fecal Coliform | Microbiological | 13 | 3 | Yes |
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 12 | 11 | No |
| Surface Water Treatment Rule | Treatment Technique | 12 | 8 | No |
| Contaminant 0700 | Other | 7 | 7 | Yes |
| Stage 2 DBP Rule | Treatment Technique | 6 | 3 | Yes |
| Total Coliform | Microbiological | 5 | 5 | No |
| Combined Radium | Radionuclides | 5 | 5 | No |
Water Quality Overview
South Dakota has 478 community water systems serving approximately 1,341,845 people across 392 ZIP codes. These systems have accumulated 379 EPA violations, including 92 health-based violations.
Health-based violations account for 24% of all violations in South Dakota. These violations indicate contaminant levels that may pose direct risks to human health, as opposed to monitoring or reporting failures.
Violation Breakdown
| Violation Type | Count | Percentage |
|---|---|---|
| Health-based | 92 | 24.3% |
| Monitoring/Reporting | 287 | 75.7% |
| Total | 379 | 100% |
Health-based violations indicate contaminant levels exceeding EPA Maximum Contaminant Levels (MCLs). Monitoring violations indicate failures to test or report — these do not necessarily mean unsafe water, but they mean the water was not properly verified.
Cities with Most Violations
The following cities in South Dakota have the highest number of EPA violations:
| Rank | City | Grade | Violations | Water Systems | Population |
|---|---|---|---|---|---|
| 1 | Sioux Falls | C | 40 | 5 | 223,087 |
| 2 | Henry | C | 19 | 1 | 256 |
| 3 | Edgemont | B | 17 | 2 | 750 |
| 4 | Aberdeen | C | 16 | 5 | 50,402 |
| 5 | Carpenter | D | 10 | 2 | 217 |
| 6 | Morristown | C | 10 | 1 | 47 |
| 7 | Rosholt | C | 9 | 2 | 487 |
| 8 | Buffalo Gap | B | 9 | 1 | 126 |
| 9 | Lesterville | C | 9 | 1 | 115 |
| 10 | Tolstoy | C | 9 | 1 | 36 |
Violation counts are cumulative across all water systems serving each city. Higher counts may reflect larger systems with more monitoring requirements, not necessarily worse water quality.
Violation Trend Over Time
Year-by-year EPA violations recorded across all water systems in South Dakota:
| Year | Total Violations | Health-Based |
|---|---|---|
| 2021 | 43 | 43 |
| 2022 | 27 | 27 |
| 2023 | 15 | 15 |
| 2024 | 41 | 41 |
| 2025 | 44 | 44 |
Violations have increased from 43 in 2021 to 44 in 2025. This trend warrants monitoring and may reflect expanded testing requirements rather than worsening quality.
Most Common Contaminants
The following contaminants have caused the most violations across South Dakota water systems:
| Contaminant | Category | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|
| Revised Total Coliform Rule | Microbiological | 97 | 65 | No |
| Chlorine residual | Disinfectant | 57 | 52 | Yes |
| Stage 1 DBP Rule | Treatment Technique | 27 | 25 | No |
| Fecal Coliform | Microbiological | 13 | 3 | Yes |
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 12 | 11 | No |
| Surface Water Treatment Rule | Treatment Technique | 12 | 8 | No |
| Stage 2 DBP Rule | Treatment Technique | 6 | 3 | Yes |
| Total Coliform | Microbiological | 5 | 5 | No |
| Combined Radium | Radionuclides | 5 | 5 | No |
| Gross Alpha | Radionuclides | 5 | 3 | Yes |
How to Check Your Water in South Dakota
Enter your ZIP code on ZipCheckup for detailed water system data including contaminant levels, violation history, and safety scores
Request your CCR — every water utility must provide an annual Consumer Confidence Report
Get a home test — certified kits ($20-$50) or professional lab tests ($150-$400)
Consider filtration — NSF-certified filters can address specific contaminants found in your area
EPA Enforcement
The EPA and state regulators have taken 1,399 enforcement actions against water systems in South Dakota. Enforcement actions range from compliance assistance to formal orders and penalties.
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Enforcement: EPA ECHO
Updated daily.
What are EPA violations?
Health-based violations mean a contaminant was detected above the EPA's Maximum Contaminant Level (MCL) — the legal limit designed to protect human health. South Dakota has 92 such violations across its water systems. Not all violations cause illness, but repeated exceedances increase risk, especially for children and immunocompromised individuals.
Understanding water quality grades
ZipCheckup grades water systems from A to F based on EPA violation history, contaminant levels, and system compliance. Grade A means few or no violations; Grade F indicates persistent or serious issues. Grades are calculated per ZIP code and aggregated at the city, county, and state level.
Wondering about your tap water?
Water quality varies by ZIP code. Enter yours to see contaminant data, violations, and filtration recommendations specific to your area.
Check Your ZIP Code Water Quality →Frequently Asked Questions
Is the tap water safe to drink in South Dakota?
South Dakota has 478 community water systems with 379 recorded EPA violations, including 92 health-based. Water quality varies by city and ZIP code — check your specific location for detailed results.
How many water violations does South Dakota have?
South Dakota has 379 total EPA violations across 392 ZIP codes. 92 are health-based violations that indicate contaminant levels potentially harmful to human health. The remainder are monitoring or reporting violations.
Which city in South Dakota has the worst water quality?
Sioux Falls, SD has the most EPA violations among major cities in South Dakota with 40 recorded violations. Check individual ZIP codes for the most accurate picture of your local water quality.
Which city in South Dakota has the best water quality?
Several cities in South Dakota maintain excellent EPA compliance. Check individual city reports for details.
What contaminants are found in South Dakota drinking water?
South Dakota water systems are monitored for over 90 EPA-regulated contaminants including lead, copper, nitrates, disinfection byproducts, and bacteria. The most common violations vary by region — check your ZIP code for contaminant-specific data.