Water Quality in Great Falls, MT: 65 Violations — Grade C
Grade C · Score 56/100 · 5 water systems · Updated 2026-05-03
Great Falls's water has moderate compliance issues. Residents in affected areas should consider filtration.
Data: EPA Safe Drinking Water Information System (SDWIS) Last verified: 2026-05-03
According to EPA filings, Great Falls, MT has 65 water compliance violations on record — sourced from SDWIS, the federal database that tracks reportable events for every registered public water system in the state.
Water Quality Map: Great Falls, MT
Each dot represents a ZIP code. Color indicates water quality grade. Tap a dot for details.
Water Quality by ZIP Code in Great Falls
Water quality varies across Great Falls's 5 ZIP codes. Check your specific ZIP for detailed contaminant data.
| ZIP Code | Grade | Score | Violations | Health | |
|---|---|---|---|---|---|
| 59404 | D | 51 | 13 | 2 | View report → |
| 59403 | D | 54 | 13 | 2 | View report → |
| 59401 | C | 56 | 13 | 2 | View report → |
| 59405 | C | 56 | 13 | 2 | View report → |
| 59406 | C | 61 | 13 | 2 | View report → |
Water Quality Overview
Great Falls, Montana receives a water quality grade of C with an overall score of 56 out of 100, based on EPA compliance data from the Safe Drinking Water Information System (SDWIS).
The 5 water systems serving Great Falls have accumulated 65 EPA violations, including 10 health-based violations. These violations are tracked across 5 ZIP codes serving approximately 72,250 people.
What Grade C Means
A grade of C indicates moderate compliance issues. Great Falls's water systems have some violations that warrant attention. While the water may still be safe for most people, residents in affected ZIP codes should consider additional testing or filtration.
Lead Levels
The average 90th percentile lead level across Great Falls water systems is 0.0080 mg/L — within EPA limits. No ZIP codes exceed the EPA lead action level.
With 76% of homes built before 1986, Great Falls 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
Great Falls 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 Great Falls
Great Falls is served by 5 community water systems regulated under the Safe Drinking Water Act. These systems collectively serve approximately 72,250 people across 5 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 50 enforcement actions against water systems serving Great Falls. Enforcement actions range from informal compliance assistance to formal orders and penalties.
How to Check Your Water in Great Falls
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 Great Falls Water Systems
The following contaminants have been detected or caused violations across Great Falls's water systems:
| Contaminant | Category | MCL | Violations | ZIPs Affected | Health-Based |
|---|---|---|---|---|---|
| Surface Water Treatment Rule | Treatment Technique | N/A | 20 | 5 | No |
| Stage 1 DBP Rule | Treatment Technique | N/A | 5 | 5 | No |
| Total Trihalomethanes (TTHM) | Disinfection Byproducts | 0.08 mg/L | 5 | 5 | No |
| Total Coliform | Microbiological | N/A | 5 | 5 | 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 10 enforcement actions against water systems serving Great Falls. Recent actions:
| Date | Action Type |
|---|---|
| 2025-07-01 | State Order Extension |
| 2025-02-04 | State Informal Action |
| 2024-12-23 | State Informal Action |
| 2024-12-23 | State Informal Enforcement |
| 2024-12-23 | State Order Extension |
| 2024-10-01 | State Informal Action |
| 2024-07-23 | State Informal Action |
| 2024-07-15 | State Informal Action |
| 2024-07-15 | State Informal Enforcement |
| 2024-07-15 | State Order Extension |
Enforcement actions range from informal compliance assistance to formal orders and penalties. The most recent action was on 2025-07-01.
Great Falls vs. Nearby Montana Cities
How Great Falls's water quality compares to similar cities in Montana:
| City | Grade | Violations | Systems | Population |
|---|---|---|---|---|
| Great Falls | C | 65 | 5 | 72,250 |
| Missoula | C | 24 | 5 | 72,009 |
| Bozeman | C | 21 | 5 | 64,118 |
| Floweree | D | 0 | 1 | 60,000 |
Water Quality by ZIP Code in Great Falls
Water quality varies across Great Falls's ZIP codes. The table below shows the worst-scoring and best-scoring areas:
| ZIP Code | Score | Grade | Violations | Health-Based |
|---|---|---|---|---|
| 59404 | 51 | D | 13 | 2 |
| 59403 | 54 | D | 13 | 2 |
| 59401 | 56 | C | 13 | 2 |
| 59405 | 56 | C | 13 | 2 |
| 59406 | 61 | C | 13 | 2 |
Common Questions About Great Falls Water
These are the most common questions residents search for about water quality in Great Falls, Montana:
Is Great Falls water hard or soft? Water hardness varies by source. Great Falls's 5 water systems use multiple sources. Check your ZIP code report for specific hardness data.
Can I drink Great Falls tap water? Great Falls's water receives a grade of C (56/100). There are 10 health-based violations — consider filtration.
What is the best water filter for Great Falls? A NSF/ANSI 53-certified filter for lead removal is a good general choice. See our Water Filter Matcher for personalized recommendations.
Great Falls vs. Montana Average
Understanding how Great Falls 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 Great Falls.
ZIP Codes in Great Falls
Great Falls spans 5 ZIP codes. The ZIP with the lowest water quality score is 59401. 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.