Montana Water Quality Report: 745 Water-System Violations Mapped to 67 ZIPs
125 water systems · 67 ZIP codes · 745 violations
Data: EPA Safe Drinking Water Information System (SDWIS), EPA ECHO
ZipCheckup tracks EPA drinking-water compliance for 125 public water systems serving 67 ZIP codes in Montana. The state record shows 745 EPA violations, 43 health-based.
City Water Quality Map: Montana
Each circle represents a city. Size indicates population, color indicates water quality grade. Tap a circle for details.
Cities with Most Violations in Montana
| # | City | Grade | Violations | Systems | Population | |
|---|---|---|---|---|---|---|
| 1 | Helena | 133 | 8 | 62,357 | Details → | |
| 2 | Great Falls | 87 | 6 | 75,786 | Details → | |
| 3 | Columbus | 80 | 1 | 4,267 | Details → | |
| 4 | Reed Point | 80 | 1 | 491 | Details → | |
| 5 | Billings | 46 | 8 | 145,092 | Details → | |
| 6 | Kalispell | 38 | 5 | 61,710 | Details → | |
| 7 | Fort Benton | 32 | 2 | 1,777 | Details → | |
| 8 | Conrad | 28 | 1 | 3,753 | Details → | |
| 9 | Brady | 28 | 1 | 378 | Details → | |
| 10 | Missoula | 27 | 14 | 100,863 | Details → |
Most Common Contaminants in Montana
| Contaminant | Category | Violations | ZIPs Affected | Health Risk |
|---|---|---|---|---|
| Consumer Confidence Rule | Reporting | 83 | 31 | No |
| Lead and Copper Rule | Treatment Technique | 58 | 24 | Yes |
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 41 | 22 | Yes |
| Nitrate-Nitrite | Inorganic | 32 | 18 | Yes |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 21 | 17 | Yes |
| E. coli | Microbiological | 18 | 12 | No |
| Surface Water Treatment Rule | Treatment Technique | 12 | 4 | Yes |
| Endrin | Organic | 11 | 7 | No |
| BHC-gamma (Lindane) | Organic | 11 | 7 | No |
| Methoxychlor | Organic | 11 | 7 | No |
Water Quality Overview
Montana has 125 community water systems represented across 67 directly mapped ZIP records. The associated city records cover approximately 845,987 people. The available records contain 745 EPA violations, including 43 health-based violations.
Health-based violations account for 6% of all violations in Montana. 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 | 43 | 5.8% |
| Monitoring/Reporting | 702 | 94.2% |
| Total | 745 | 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 Montana have the highest number of EPA violations:
| Rank | City | Violations | Water Systems | Population |
|---|---|---|---|---|
| 1 | Helena | 133 | 8 | 62,357 |
| 2 | Great Falls | 87 | 6 | 75,786 |
| 3 | Columbus | 80 | 1 | 4,267 |
| 4 | Reed Point | 80 | 1 | 491 |
| 5 | Billings | 46 | 8 | 145,092 |
| 6 | Kalispell | 38 | 5 | 61,710 |
| 7 | Fort Benton | 32 | 2 | 1,777 |
| 8 | Conrad | 28 | 1 | 3,753 |
| 9 | Brady | 28 | 1 | 378 |
| 10 | Missoula | 27 | 14 | 100,863 |
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 Montana:
| Year | Health-based violations |
|---|---|
| 2021 | 1 |
| 2022 | 14 |
| 2023 | 21 |
| 2024 | 4 |
| 2025 | 1 |
Most Common Contaminants
The following contaminants have caused the most violations across Montana water systems:
| Contaminant | Category | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|
| Consumer Confidence Rule | Reporting | 83 | 31 | No |
| Lead and Copper Rule | Treatment Technique | 58 | 24 | Yes |
| Haloacetic Acids (HAA5) | Disinfection Byproducts | 41 | 22 | Yes |
| Nitrate-Nitrite | Inorganic | 32 | 18 | Yes |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 21 | 17 | Yes |
| E. coli | Microbiological | 18 | 12 | No |
| Surface Water Treatment Rule | Treatment Technique | 12 | 4 | Yes |
| Di(2-ethylhexyl) phthalate | Organic | 11 | 7 | No |
| Atrazine | Organic | 11 | 7 | No |
| 1,2,4-Trichlorobenzene | Organic | 9 | 8 | No |
How to Check Your Water in Montana
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 Montana. 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. Montana has 43 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 Montana?
Records for 125 community water systems mapped to ZIPs in Montana show 745 reported violations, including 43 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 Montana?
Montana has 745 EPA violations on record across 67 ZIP codes; 43 are classified as health-based violations. The remainder are monitoring or reporting violations.
Which city in Montana has the worst water quality?
Helena, MT has the most recorded EPA violations (133) among the cities with mapped water systems in Montana 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 Montana has the best water quality?
Violation records vary by water system across Montana. Check individual city reports for details.
What contaminants are found in Montana drinking water?
EPA regulates over 90 drinking-water contaminants nationally; water systems in Montana 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.