South Dakota Water Quality Report: 234 Water-System Violations Mapped to 293 ZIPs
534 water systems · 293 ZIP codes · 234 violations
Data: EPA Safe Drinking Water Information System (SDWIS), EPA ECHO
ZipCheckup tracks EPA drinking-water compliance for 534 public water systems serving 293 ZIP codes in South Dakota. The state record shows 234 EPA violations, 44 health-based.
City Water Quality Map: South Dakota
Each circle represents a city. Size indicates population, color indicates water quality grade. Tap a circle for details.
Cities with Most Violations in South Dakota
| # | City | Grade | Violations | Systems | Population | |
|---|---|---|---|---|---|---|
| 1 | Aberdeen | 20 | 5 | 32,064 | Details → | |
| 2 | Rapid City | 12 | 12 | 98,535 | Details → | |
| 3 | Box Elder | 12 | 5 | 11,475 | Details → | |
| 4 | Ellsworth Afb | 9 | 2 | 3,009 | Details → | |
| 5 | Sioux Falls | 7 | 9 | 204,373 | Details → | |
| 6 | Spearfish | 7 | 4 | 17,507 | Details → | |
| 7 | Eagle Butte | 6 | 2 | 3,857 | Details → | |
| 8 | Watertown | 4 | 4 | 26,375 | Details → | |
| 9 | Faith | 4 | 2 | 909 | Details → | |
| 10 | South Shore | 4 | 3 | 488 | Details → |
Most Common Contaminants in South Dakota
| Contaminant | Category | Violations | ZIPs Affected | Health Risk |
|---|---|---|---|---|
| Chlorine | Disinfectant | 57 | 46 | No |
| Gross Alpha (excl. radon and uranium) | Radionuclides | 29 | 17 | Yes |
| Combined Radium (-226 and -228) | Radionuclides | 26 | 17 | Yes |
| Nitrate | Inorganic | 24 | 24 | No |
| Combined Uranium | Radionuclides | 14 | 14 | No |
| Stage 1 Disinfectants and Disinfection Byproducts Rule | Treatment Technique | 8 | 6 | Yes |
| Interim Enhanced Surface Water Treatment Rule | Treatment Technique | 7 | 1 | Yes |
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 6 | 6 | No |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 6 | 6 | No |
| Lead and Copper Rule | Treatment Technique | 5 | 4 | No |
Water Quality Overview
South Dakota has 534 community water systems represented across 293 directly mapped ZIP records. The associated city records cover approximately 858,325 people. The available records contain 234 EPA violations, including 44 health-based violations.
Health-based violations account for 19% 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 | 44 | 18.8% |
| Monitoring/Reporting | 190 | 81.2% |
| Total | 234 | 100% |
Health-based violations are MCL, MRDL (disinfectant) and treatment-technique violations. 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 | Violations | Water Systems | Population |
|---|---|---|---|---|
| 1 | Aberdeen | 20 | 5 | 32,064 |
| 2 | Rapid City | 12 | 12 | 98,535 |
| 3 | Box Elder | 12 | 5 | 11,475 |
| 4 | Ellsworth Afb | 9 | 2 | 3,009 |
| 5 | Sioux Falls | 7 | 9 | 204,373 |
| 6 | Spearfish | 7 | 4 | 17,507 |
| 7 | Eagle Butte | 6 | 2 | 3,857 |
| 8 | Watertown | 4 | 4 | 26,375 |
| 9 | Faith | 4 | 2 | 909 |
| 10 | South Shore | 4 | 3 | 488 |
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 | Health-based violations |
|---|---|
| 2021 | 8 |
| 2022 | 15 |
| 2023 | 1 |
| 2024 | 7 |
| 2025 | 11 |
| 2026 | 1 |
Health-based violations have decreased from 8 in 2021 to 1 in 2026, suggesting improving compliance across South Dakota.
Most Common Contaminants
The following contaminants have caused the most violations across South Dakota water systems:
| Contaminant | Category | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|
| Chlorine | Disinfectant | 57 | 46 | No |
| Gross Alpha (excl. radon and uranium) | Radionuclides | 29 | 17 | Yes |
| Combined Radium (-226 and -228) | Radionuclides | 26 | 17 | Yes |
| Nitrate | Inorganic | 24 | 24 | No |
| Combined Uranium | Radionuclides | 14 | 14 | No |
| Stage 1 Disinfectants and Disinfection Byproducts Rule | Treatment Technique | 8 | 6 | Yes |
| Interim Enhanced Surface Water Treatment Rule | Treatment Technique | 7 | 1 | Yes |
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 6 | 6 | No |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 6 | 6 | No |
| Lead and Copper Rule | Treatment Technique | 5 | 4 | No |
How to Check Your Water in South Dakota
Enter your ZIP code on ZipCheckup for detailed water-system data including contaminant levels and violation history; the separate Home Safety Score is a multi-source index
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 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 are EPA violations of a Maximum Contaminant Level (MCL), a Maximum Residual Disinfectant Level (MRDL) or a required treatment technique - the enforceable standards designed to protect human health. South Dakota has 44 such violations across its water systems. Not all violations cause illness; review each violation type and duration to understand possible health implications.
Understanding water quality grades
ZipCheckup grades water systems from A to F based on EPA violation history, contaminant levels, and system compliance. Grades summarize ZipCheckup's scoring inputs; review the underlying records for specific 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?
Records for 534 community water systems mapped to ZIPs in South Dakota show 234 reported violations, including 44 health-based. Water quality varies by city and ZIP code - check your specific location for detailed results.
How many violations are on record for water systems serving South Dakota?
South Dakota has 234 EPA violations on record across 293 ZIP codes; 44 are classified as health-based violations. The remainder are monitoring or reporting violations.
Which city in South Dakota has the worst water quality?
Aberdeen, SD has the most recorded EPA violations (20) among the cities with mapped water systems in South Dakota in our data. Check your water supplier's report and test your tap water for the most accurate picture of your local water quality.
Which city in South Dakota has the best water quality?
Violation records vary by water system across South Dakota. Check individual city reports for details.
What contaminants are found in South Dakota drinking water?
EPA regulates over 90 drinking-water contaminants nationally; water systems in South Dakota monitor those applicable to each system, which can include lead, copper, nitrate, disinfection byproducts, and bacteria. The most common violations vary by region - check your ZIP code for contaminant-specific data.