Wyoming Water Quality Report: 790 Violations Across 48 ZIPs
98 water systems · 48 ZIP codes · 790 violations · Updated
Data: EPA Safe Drinking Water Information System (SDWIS), EPA ECHO Last verified:
ZipCheckup tracks EPA drinking-water compliance for 98 public water systems serving 48 ZIP codes in Wyoming. The state record shows 790 EPA violations, 64 health-based.
City Water Quality Map: Wyoming
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 Wyoming.
Cities with Most Violations in Wyoming
| # | City | Grade | Violations | Systems | Population | |
|---|---|---|---|---|---|---|
| 1 | Jackson | 196 | 4 | 17,458 | Details → | |
| 2 | Wilson | 188 | 4 | 2,807 | Details → | |
| 3 | Newcastle | 162 | 3 | 5,411 | Details → | |
| 4 | Riverton | 88 | 4 | 18,946 | Details → | |
| 5 | Rawlins | 38 | 1 | 8,267 | Details → | |
| 6 | Cheyenne | 12 | 8 | 95,110 | Details → | |
| 7 | Kemmerer | 10 | 1 | 3,576 | Details → | |
| 8 | Frontier | 10 | 1 | 3,348 | Details → | |
| 9 | Diamondville | 10 | 1 | 603 | Details → | |
| 10 | Casper | 8 | 6 | 73,288 | Details → |
Most Common Contaminants in Wyoming
| Contaminant | Category | Violations | ZIPs Affected | Health Risk |
|---|---|---|---|---|
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 45 | 15 | Yes |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 22 | 11 | Yes |
| Surface Water Treatment Rule | Treatment Technique | 22 | 10 | No |
| Stage 1 DBP Rule | Treatment Technique | 20 | 11 | No |
| Barium | Inorganic | 14 | 5 | No |
| Cadmium | Inorganic | 13 | 5 | No |
| Chromium | Inorganic | 13 | 5 | No |
| Fluoride | Inorganic | 13 | 5 | No |
| Selenium | Inorganic | 13 | 5 | No |
| Nickel | Inorganic | 13 | 5 | No |
Water Quality Overview
Wyoming has 98 community water systems represented across 48 directly mapped ZIP records. The associated city records cover approximately 499,669 people. The available records contain 790 EPA violations, including 64 health-based violations.
Health-based violations account for 8% of all violations in Wyoming. 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 | 64 | 8.1% |
| Monitoring/Reporting | 726 | 91.9% |
| Total | 790 | 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 Wyoming have the highest number of EPA violations:
| Rank | City | Violations | Water Systems | Population |
|---|---|---|---|---|
| 1 | Jackson | 196 | 4 | 17,458 |
| 2 | Wilson | 188 | 4 | 2,807 |
| 3 | Newcastle | 162 | 3 | 5,411 |
| 4 | Riverton | 88 | 4 | 18,946 |
| 5 | Rawlins | 38 | 1 | 8,267 |
| 6 | Cheyenne | 12 | 8 | 95,110 |
| 7 | Kemmerer | 10 | 1 | 3,576 |
| 8 | Frontier | 10 | 1 | 3,348 |
| 9 | Diamondville | 10 | 1 | 603 |
| 10 | Casper | 8 | 6 | 73,288 |
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 Wyoming:
| Year | Total Violations | Health-Based |
|---|---|---|
| 2021 | 5 | 5 |
| 2022 | 6 | 6 |
| 2023 | 18 | 18 |
| 2024 | 52 | 52 |
| 2025 | 17 | 17 |
Violations have increased from 5 in 2021 to 17 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 Wyoming water systems:
| Contaminant | Category | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 45 | 15 | Yes |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 22 | 11 | Yes |
| Surface Water Treatment Rule | Treatment Technique | 22 | 10 | No |
| Stage 1 DBP Rule | Treatment Technique | 20 | 11 | No |
| Barium | Inorganic | 14 | 5 | No |
| Cadmium | Inorganic | 13 | 5 | No |
| Chromium | Inorganic | 13 | 5 | No |
| Fluoride | Inorganic | 13 | 5 | No |
| Selenium | Inorganic | 13 | 5 | No |
| Nickel | Inorganic | 13 | 5 | No |
How to Check Your Water in Wyoming
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 372 enforcement actions against water systems in Wyoming. 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. Wyoming has 64 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 Wyoming?
Wyoming has 98 community water systems with 790 recorded EPA violations, including 64 health-based. Water quality varies by city and ZIP code - check your specific location for detailed results.
How many water violations does Wyoming have?
Wyoming has 790 total EPA violations across 48 ZIP codes. 64 are health-based violations that indicate contaminant levels potentially harmful to human health. The remainder are monitoring or reporting violations.
Which city in Wyoming has the worst water quality?
Jackson, WY has the most EPA violations among major cities in Wyoming with 196 recorded violations. Check individual ZIP codes for the most accurate picture of your local water quality.
Which city in Wyoming has the best water quality?
Several cities in Wyoming maintain excellent EPA compliance. Check individual city reports for details.
What contaminants are found in Wyoming drinking water?
Wyoming 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.