Water Quality in Hamilton, MT: 1 Violation — Grade B
Grade B · Score 70/100 · 5 water systems · Updated 2026-05-03
Hamilton's water is mostly safe. Minor violations exist but are primarily monitoring-related.
Data: EPA Safe Drinking Water Information System (SDWIS) Last verified: 2026-05-03
Water systems in Hamilton, MT have accumulated 1 EPA violation across the full compliance record — a dataset that captures reportable health-based exceedances, monitoring lapses, and enforcement actions filed with the federal Safe Drinking Water Information System.
Water Quality by ZIP Code in Hamilton
Water quality varies across Hamilton's 1 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 59840 | B | 70 | 1 | 0 | View report → |
Water Quality Overview
Hamilton, Montana receives a water quality grade of B with an overall score of 70 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 5 water systems serving Hamilton have accumulated 1 EPA violations (all monitoring/reporting type). These violations are tracked across 1 ZIP codes serving approximately 6,153 people.
What Grade B Means
A grade of B indicates good compliance with EPA drinking water standards. While not perfect, Hamilton's water systems meet the vast majority of federal requirements. Minor violations may exist but typically relate to monitoring or reporting rather than health-based standards.
Lead Levels
The average 90th percentile lead level across Hamilton water systems is 0.0010 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
With 56% of homes built before 1986, Hamilton 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
Hamilton 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 Hamilton
Hamilton is served by 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 6,153 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 7 enforcement actions against water systems serving Hamilton. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Hamilton
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 Hamilton Water Systems
The following contaminants have been detected or caused violations across Hamilton's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| 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.
EPA Enforcement History
The EPA and state regulators have taken 7 enforcement actions against water systems serving Hamilton. Recent actions:
| Date | Action Type |
|---|---|
| 2025-03-17 | State Order Extension |
| 2025-02-04 | State Informal Action |
| 2024-07-31 | State Order Extension |
| 2024-07-23 | State Informal Action |
| 2023-02-23 | State Order Extension |
| 2023-01-29 | State Informal Action |
| 2023-01-29 | State Informal Enforcement |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-03-17.
Hamilton vs. Nearby Montana Cities
How Hamilton's water quality compares to similar cities in Montana:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Hamilton | B | 1 | 5 | 6,153 |
| Polson | C | 2 | 5 | 6,155 |
| Molt | D | 0 | 1 | 6,339 |
| Park City | C | 0 | 1 | 6,339 |
Common Questions About Hamilton Water
These are the most common questions residents search for about water quality in Hamilton, Montana:
Is Hamilton water hard or soft? Water hardness varies by source. Hamilton's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Hamilton tap water? Hamilton's water receives a grade of B (70/100). No health-based violations have been recorded, but home testing is always recommended.
What is the best water filter for Hamilton? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Hamilton vs. Montana Average
Understanding how Hamilton 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 Hamilton.
ZIP Codes in Hamilton
Hamilton spans 1 ZIP code. The ZIP with the lowest water quality score is 59840. 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.
Frequently Asked Questions
Your Water is Safe — Here's How to Keep It That Way
Grade B is excellent news. Here's what proactive homeowners do to maintain water quality:
Annual Water Testing
EPA recommends annual testing even with clean water. Home test kits: $20-$50. Catches changes before they become problems.
Maintenance Filtration
A basic carbon filter removes chlorine taste and catches emerging contaminants like PFAS that aren't yet fully regulated.
Plumbing Check
Even safe city water picks up lead from home pipes. If your home was built before 1986, a one-time pipe inspection is recommended.