Water Quality in Lewistown, MT: 27 Violations — Grade D
Grade D · Score 40/100 · 5 water systems · Updated 2026-05-03
Lewistown's water has significant violations. Water testing and filtration are recommended.
Data: EPA Safe Drinking Water Information System (SDWIS) Last verified: 2026-05-03
Drinking water compliance data for Lewistown, MT reflects 27 EPA violations — details in the grid below.
Water Quality by ZIP Code in Lewistown
Water quality varies across Lewistown's 1 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 59457 | D | 40 | 27 | 19 | View report → |
Violation Trend
EPA violations recorded for water systems serving Lewistown.
Water Quality Overview
Lewistown, Montana receives a water quality grade of D with an overall score of 40 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 5 water systems serving Lewistown have accumulated 27 EPA violations, including 19 health-based violations. These violations are tracked across 1 ZIP codes serving approximately 6,398 people.
What Grade D Means
A grade of D indicates significant compliance issues. Lewistown's water systems have accumulated violations that suggest ongoing water quality challenges. Residents should check their specific ZIP code report and consider water testing or filtration.
Lead Levels
The average 90th percentile lead level across Lewistown water systems is 0.0050 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
With 71% of homes built before 1986, Lewistown has a higher-than-average risk of lead from older plumbing. Lead solder was banned in 1986, and homes built before this date may have lead in pipes, solder joints, or fixtures.
Radon Risk
Lewistown is in EPA Radon Zone 1 (High risk). The EPA recommends all homes in Zone 1 areas be tested for radon. Radon is the second leading cause of lung cancer after smoking.
Water Systems Serving Lewistown
Lewistown is served by 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 6,398 people across 1 ZIP codes.
Each water system is identified by a Public Water System ID (PWSID) and is required to:
- Test for over 90 regulated contaminants on a regular schedule
- Report results to the EPA and state regulators
- Issue an annual Consumer Confidence Report (CCR) to all customers
- Take corrective action when violations occur
The EPA has taken 10 enforcement actions against water systems serving Lewistown. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Lewistown
Enter your ZIP code on ZipCheckup to see your specific water system data, including contaminant levels, violation history, and safety scores
Request your CCR — your water utility must provide an annual Consumer Confidence Report with detailed test results for all monitored contaminants
Get a home test — certified kits cost $20–$50 and test for lead, bacteria, and common contaminants. Professional lab tests ($150–$400) cover a broader panel
Consider filtration — NSF-certified filters can remove specific contaminants. Reverse osmosis removes the broadest range; activated carbon is effective for chlorine and many organics
Check for advisories — monitor your local utility website and local news for boil water advisories or system alerts
Contaminants Detected in Lewistown Water Systems
The following contaminants have been detected or caused violations across Lewistown's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Arsenic | Inorganic | 0.01 mg/L | 20 | 1 | Yes |
| Surface Water Treatment Rule | Treatment Technique | N/A | 2 | 1 | No |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 0.08 mg/L | 1 | 1 | No |
| Stage 1 DBP Rule | Treatment Technique | N/A | 1 | 1 | No |
MCL = Maximum Contaminant Level (EPA enforceable standard). Health-based violations indicate levels that may pose direct health risks.
Violation Trend Over Time
Year-by-year EPA violations recorded for water systems serving Lewistown:
| Year | Total Violations | Health-Based |
|---|---|---|
| 2022 | 3 | 3 |
| 2023 | 4 | 4 |
| 2024 | 4 | 4 |
| 2025 | 4 | 4 |
Violations have increased from 3 in 2022 to 4 in 2025. This trend warrants monitoring.
EPA Enforcement History
The EPA and state regulators have taken 9 enforcement actions against water systems serving Lewistown. Recent actions:
| Date | Action Type |
|---|---|
| 2025-12-24 | State Informal Action |
| 2025-12-24 | State Informal Enforcement |
| 2025-11-05 | State Informal Action |
| 2025-10-22 | State Informal Action |
| 2025-10-22 | State Informal Enforcement |
| 2025-10-14 | State Informal Action |
| 2025-10-14 | State Informal Enforcement |
| 2025-07-17 | State Informal Action |
| 2025-07-17 | State Order Extension |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-12-24.
Lewistown vs. Nearby Montana Cities
How Lewistown's water quality compares to similar cities in Montana:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Lewistown | D | 27 | 5 | 6,398 |
| Molt | D | 0 | 1 | 6,339 |
| Park City | C | 0 | 1 | 6,339 |
| Columbia Falls | C | 2 | 5 | 6,505 |
Common Questions About Lewistown Water
These are the most common questions residents search for about water quality in Lewistown, Montana:
Is Lewistown water hard or soft? Water hardness varies by source. Lewistown's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Lewistown tap water? Lewistown's water receives a grade of D (40/100). There are 19 health-based violations — consider filtration.
What is the best water filter for Lewistown? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Lewistown vs. Montana Average
Understanding how Lewistown compares to the broader Montana average helps contextualize your local water quality. Factors like water source, treatment methods, and infrastructure age all contribute to differences between cities in the same state.
To see how individual neighborhoods compare, check the ZIP code reports below — water quality can vary significantly even within Lewistown.
ZIP Codes in Lewistown
Lewistown spans 1 ZIP code. The ZIP with the lowest water quality score is 59457. Each ZIP code has its own water quality profile based on the specific water system serving that area. Check each ZIP code for detailed contaminant data, violation history, and system information.
Data Sources
- Water quality: EPA Safe Drinking Water Information System (SDWIS)
- Lead/copper: EPA Lead and Copper Rule sampling data
- Radon: EPA Map of Radon Zones
- Enforcement: EPA ECHO database
- Filter recommendations: NSF/ANSI certified products
Updated daily.