Is Great Falls, MT Tap Water Safe to Drink?
Graded F — but Copper was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
34.5/100
waterverge.com Great Falls, MT — Water Quality Report
Great Falls's drinking water received a grade of F (34.5 out of 100), indicating failing water quality. The city's 27 water systems serve approximately 75,779 residents using surface water.
Lead levels were measured at 12.0 ppb (90th percentile), which is within EPA limits but above recommended levels. UCMR 5 testing detected 2 PFAS compounds in the water supply.
The system has 1361 violations on record, including 64 health-based violations. 214 remain unresolved.
What to know about Great Falls's water
Great Falls ranks #115 out of 115 cities in Montana for water quality, placing it among the lowest-rated in the state.
The city draws from surface water sources, which are more susceptible to seasonal runoff and agricultural contamination, requiring extensive multi-barrier treatment including coagulation, filtration, and disinfection.
PFAS compounds were detected in testing, though levels remain within current EPA limits. Residents seeking extra precaution may consider an activated carbon or reverse osmosis filter.
Haloacetic acid (HAA5) levels were elevated at 32.0 µg/L in UCMR 4 testing, though below the 60 µg/L EPA limit. Activated carbon filtration can help reduce these disinfection byproducts.
Hexavalent chromium (chromium-6) was detected at 0.07 µg/L in UCMR 3 testing. While below California's 10 µg/L limit and with no federal MCL set, residents sensitive to this contaminant may consider reverse osmosis filtration.
While lead levels are within EPA limits, they are above the recommended 5 ppb threshold that health organizations consider ideal. A point-of-use filter adds an extra layer of protection.
The system has seen 162 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Great Falls, MT water safe to drink?
Great Falls's drinking water has significant quality concerns based on EPA testing data. With a grade of F (34.5/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 27 water systems serve approximately 75,779 residents using surface water (rivers, lakes, or reservoirs).
Recent water quality updates for Great Falls
A timeline of significant water quality events, violations, and data updates.
Detected at levels within current EPA limits. PFAS persist indefinitely in the environment.
Latest EPA compliance and testing data incorporated into Great Falls's water quality assessment. Grade: F (34.5/100).
Contaminants: Revised Total Coliform Rule.
Contaminants: E. COLI, Revised Total Coliform Rule, Consumer Confidence Rule.
Contaminants: Revised Total Coliform Rule.
Federal disaster declaration (FEMA DR-3253). Hurricane event — may have impacted local water infrastructure.
Key contaminant findings
Based on the most recent EPA sampling data for Great Falls's water supply.
Within EPA limits but above the American Academy of Pediatrics recommended level of 1 ppb. An NSF 53-certified filter provides additional protection.
Exceeds EPA action level. Copper can leach from household plumbing — flush taps for 30 seconds before drinking.
Detected but within current EPA limits. PFAS do not break down in the environment and can accumulate in the body over time. An activated carbon filter can reduce exposure.
PFAS "forever chemicals" detected
UCMR 5 testing found 2 PFAS compounds in Great Falls's water supply. PFAS are synthetic chemicals that persist indefinitely in the environment and the human body.
Violation history
Great Falls's water system has 1,361 total violations on record, including 64 health-based violations. 214 remain unresolved. 162 violations were issued in the last 5 years.
Flood & environmental risk
Cascade County has experienced 3 federally declared disasters since 1975. Flooding and severe storms can overwhelm water treatment plants, cause sewage overflows, and introduce agricultural runoff, bacteria, and sediment into drinking water supplies. Local water sources include Missouri River Near Ulm.
Where does Great Falls's water come from?
Great Falls's drinking water comes from surface water (rivers, lakes, or reservoirs), supplied by 27 water systems serving approximately 75,779 people. Surface water sources are more susceptible to contamination from runoff, industrial discharge, and algal blooms, requiring extensive treatment. Nearby water bodies include Missouri River Near Ulm (river).
What Great Falls residents can do
Recommended: Activated carbon or reverse osmosis filter. This addresses the specific contaminants found in Great Falls's water.
Your water utility is required to publish an annual Consumer Confidence Report (CCR) with detailed testing results. Ask for the latest copy or check your utility's website.
Run cold water for 30 seconds before drinking, especially in the morning. Lead and copper leach from household plumbing when water sits in pipes.
Great Falls's area has a history of flooding. After severe weather, watch for boil water advisories from your local utility.
Data: EPA SDWIS, UCMR 5 (PFAS), FEMA, NOAA. Last updated May 2026.
Top contaminants to know
View all ↓Forever chemicals overview
National PFAS report →Violation summary
Violations & advisories
Top industrial polluters within 10 miles of Great Falls
Industrial polluters nearby
Reported releases to surface water by facilities near Great Falls, ranked by pounds discharged annually.
| Facility | Top chemical | To surface water (lbs/yr) | Distance |
|---|---|---|---|
US DOD USAF MALMSTROM AFB MALMSTROM AFB, MT594027536 | — | — | 5.3 mi |
CHS GREAT FALLS FEED GREAT FALLS, MT59405 | — | — | 3.9 mi |
CALUMET MONTANA REFINING LLC. GREAT FALLS, MT59404 | — | — | 1.7 mi |
Source: EPA Toxic Release Inventory (TRI) 2023
Superfund sites within 10 miles of Great Falls
Superfund sites nearby
Federally tracked hazardous-waste sites on the EPA National Priorities List. Proximity does not necessarily indicate tap-water contamination — the connection depends on hydrology and treatment.
- ACM SMELTER AND REFINERY3.1 mi
Source: EPA Superfund National Priorities List
Drought conditions
D3 — extreme droughtCascade County is currently in D3 (extreme drought) per the U.S. Drought Monitor (week of May 5, 2026). Drought can elevate disinfection-byproduct (TTHM/HAA5) levels and taste/odor issues as utilities draw from lower reservoirs.
Source: U.S. Drought Monitor, updated weekly by NDMC, USDA, and NOAA.
Flood & disaster history
Cascade County has experienced 3 federally declared disasters since 1975. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Recommended water filters
Based on contaminants detected in Great Falls's water supply, we recommend the following filter types.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 12.0 | 15 | ppb | Inorganic | Near Limit |
| Copper (90th percentile) CopperInorganic A metal that enters drinking water mainly through corrosion of copper plumbing. Small amounts are essential for health, but excess levels are harmful. Health EffectsGastrointestinal distress (nausea, vomiting, diarrhea) at short-term high levels; liver and kidney damage from long-term exposure. EPA Limit1.3 mg/L action level Common SourcesCorrosion of copper household plumbing, erosion of natural deposits. | 2.21 | 1.3 | mg/L | Inorganic | Over Limit |
| 11Cl-PF3OUdS | ND | HI | µg/L | PFAS | Not Detected |
| 4:2 FTS | ND | HI | µg/L | PFAS | Not Detected |
| 6:2 FTS 6:2 FTSPFAS A fluorotelomer sulfonate commonly found at sites contaminated with aqueous film-forming foam (AFFF) used in firefighting. Health EffectsPotential liver toxicity and endocrine disruption. Less studied but identified as a contaminant of concern. EPA LimitNo individual MCL (not yet regulated) Common SourcesFirefighting foam (AFFF), airports, military bases, and industrial facilities. | ND | HI | µg/L | PFAS | Not Detected |
| 8:2 FTS | ND | HI | µg/L | PFAS | Not Detected |
| 9Cl-PF3ONS | ND | HI | µg/L | PFAS | Not Detected |
| ADONA | ND | HI | µg/L | PFAS | Not Detected |
| HFPO-DA HFPO-DA (GenX)PFAS A replacement for PFOA in manufacturing, marketed as safer but still a persistent "forever chemical." Also known as GenX. Health EffectsLiver and kidney effects, reproductive toxicity, immune system effects, and potential cancer risk. EPA Limit10 ppt MCL Common SourcesFluoropolymer manufacturing (used as PFOA replacement), industrial wastewater discharge. | ND | 0.01 | µg/L | PFAS | Not Detected |
| lithium LithiumInorganic A naturally occurring alkali metal found in groundwater. Monitored under UCMR 5 to assess occurrence in drinking water. Health EffectsKidney effects at high doses. Low-level exposure effects under study; some research suggests neurological effects. EPA LimitNo MCL (monitoring only under UCMR 5) Common SourcesNatural mineral deposits, geothermal water, and industrial discharge. | 80.800 | HI | µg/L | PFAS | Detected |
| NEtFOSAA | ND | HI | µg/L | PFAS | Not Detected |
| NFDHA | ND | HI | µg/L | PFAS | Not Detected |
| NMeFOSAA | ND | HI | µg/L | PFAS | Not Detected |
| PFBA PFBAPFAS One of the shortest-chain PFAS compounds. Very mobile in water and difficult to remove with standard filtration. Health EffectsThyroid effects, potential developmental toxicity. Shorter half-life in body than long-chain PFAS. EPA LimitNo individual MCL (not yet regulated) Common SourcesDegradation of longer-chain PFAS, industrial discharge, and firefighting foam. | 0.007 | HI | µg/L | PFAS | Detected |
| PFBS PFBSPFAS A short-chain PFAS used as a replacement for PFOS. While it clears the body faster than long-chain PFAS, it still persists in the environment. Health EffectsThyroid effects, reproductive and developmental toxicity, kidney effects. EPA LimitPart of Hazard Index (1.0) Common SourcesIndustrial discharge, firefighting foam, and as a replacement chemical in manufacturing. | ND | HI | µg/L | PFAS | Not Detected |
| PFDA | ND | HI | µg/L | PFAS | Not Detected |
| PFDoA | ND | HI | µg/L | PFAS | Not Detected |
| PFEESA | ND | HI | µg/L | PFAS | Not Detected |
| PFHpA PFHpAPFAS A medium-chain PFAS compound found in various environmental samples. Less studied than PFOA/PFOS but still considered a contaminant of concern. Health EffectsLiver effects, potential developmental toxicity, and endocrine disruption. EPA LimitPart of Hazard Index (1.0) Common SourcesDegradation of longer-chain PFAS, industrial discharge, and contaminated water sources. | ND | HI | µg/L | PFAS | Not Detected |
| PFHpS | ND | HI | µg/L | PFAS | Not Detected |
| PFHxA PFHxAPFAS A short-chain PFAS replacement chemical widely used after manufacturers phased out longer-chain PFAS. Very commonly detected in water. Health EffectsLiver and kidney effects, potential thyroid disruption. Considered less toxic than long-chain PFAS but still persistent. EPA LimitNo individual MCL (not yet regulated) Common SourcesIndustrial processes, firefighting foam (AFFF), food packaging, and textile treatment. | ND | HI | µg/L | PFAS | Not Detected |
| PFHxS PFHxSPFAS A medium-chain PFAS found in firefighting foam and consumer products. It has a long half-life in the human body, similar to long-chain PFAS. Health EffectsImmune system effects, thyroid disruption, and potential reproductive and developmental harm. EPA LimitPart of Hazard Index (1.0) Common SourcesFirefighting foam (AFFF), waterproof textiles, food packaging, and industrial discharge. | ND | HI | µg/L | PFAS | Not Detected |
| PFMBA | ND | HI | µg/L | PFAS | Not Detected |
| PFMPA | ND | HI | µg/L | PFAS | Not Detected |
| PFNA PFNAPFAS A long-chain PFAS compound used in manufacturing fluoropolymers. It bioaccumulates in the body and is very persistent in the environment. Health EffectsDevelopmental effects, liver toxicity, immune suppression, and potential cancer risk. EPA LimitPart of Hazard Index (1.0) Common SourcesFluoropolymer manufacturing, industrial emissions, and contaminated water sources. | ND | HI | µg/L | PFAS | Not Detected |
| PFOA PFOAPFAS A long-chain PFAS ("forever chemical") once widely used in nonstick coatings and firefighting foam. It persists in the body and environment for years. Health EffectsLinked to kidney and testicular cancer, thyroid disease, elevated cholesterol, and reproductive issues. EPA Limit4.0 ppt MCL Common SourcesIndustrial discharge, firefighting foam (AFFF), nonstick cookware manufacturing, and contaminated groundwater. | ND | 0.004 | µg/L | PFAS | Not Detected |
| PFOS PFOSPFAS A long-chain PFAS compound historically used in stain-resistant coatings and firefighting foam. One of the most studied and persistent PFAS chemicals. Health EffectsLiver damage, immune system suppression, thyroid disruption, increased cholesterol, and potential cancer risk. EPA Limit4.0 ppt MCL Common SourcesFirefighting foam (AFFF), industrial sites, stain-resistant fabric treatments, and contaminated groundwater. | ND | 0.004 | µg/L | PFAS | Not Detected |
| PFPeA PFPeAPFAS A short-chain PFAS compound commonly detected in drinking water. One of the most frequently found PFAS in UCMR 5 monitoring. Health EffectsLess studied than PFOA/PFOS. Potential liver and thyroid effects. Research is ongoing. EPA LimitNo individual MCL (not yet regulated) Common SourcesIndustrial discharge, firefighting foam degradation, and consumer products. | ND | HI | µg/L | PFAS | Not Detected |
| PFPeS | ND | HI | µg/L | PFAS | Not Detected |
| PFTA | ND | HI | µg/L | PFAS | Not Detected |
| PFTrDA | ND | HI | µg/L | PFAS | Not Detected |
| PFUnA | ND | HI | µg/L | PFAS | Not Detected |
Lead level trend (90th percentile)
Copper level trend (90th percentile)
See how Great Falls compares by contaminant
Explore where Great Falls ranks among all Montana cities for specific contaminants.
Water source & infrastructure
Where Great Falls's water comes from
Great Falls's drinking water comes primarily from surface water sources such as rivers, lakes, or reservoirs.
Surface water systems require multi-stage treatment including coagulation, sedimentation, filtration, and disinfection to meet EPA Safe Drinking Water Act standards.
These sources can be impacted by seasonal changes, stormwater runoff, upstream agriculture, and industrial discharge.
The system is operated by local government ownership and serves approximately 75,779 people through 27 water systems.
Water bodies near Great Falls
Great Falls is located near 1 notable water body. As a surface water system, these water bodies may directly influence the city's drinking water supply.
Water systems serving Great Falls
| System Name | PWSID | Population | Source |
|---|---|---|---|
| GREAT FALLS CITY OF | MT0000525 | 60,000 | SW |
| MALMSTROM AIR FORCE BASE | MT0000515 | 8,850 | SWP |
| SUN PRAIRIE VILLAGE COUNTY | MT0000521 | 1,800 | GW |
| PRAIRIE WATER COMPANY | MT0003539 | 1,000 | SWP |
| COUNTRYSIDE VILLAGE MHP GRT FLS | MT0004830 | 600 | SWP |
| GORE HILL COUNTY WATER DIST | MT0000232 | 500 | GW |
| BUSHARD WATER COMPANY | MT0005164 | 425 | SWP |
| HIGHWOOD MOBILE HOME PARK | MT0004681 | 400 | SWP |
| SUN PRAIRIE WATER DISTRICT | MT0000571 | 350 | GW |
| GREAT FALLS RV PARK | MT0000027 | 274 | SWP |
| RYAN DAM WATER SYSTEM | MT0000046 | 230 | GW |
| SOUTH WIND WATER AND SEWER DISTRICT | MT0000025 | 200 | GW |
| GRANDVIEW TRAILER COURT | MT0004686 | 165 | SWP |
| PLEASANT PARK COMMUNITY INC | MT0000028 | 125 | GW |
| BIG BEND RANCH SUBDIVISION | MT0004261 | 100 | GW |
| SHADE TREE MOBILE PARK | MT0004685 | 100 | SWP |
| RIVERSHORE COMMUNITY LLC | MT0000414 | 90 | SWP |
| MISSOURI MEADOWS COMMUNITY INC | MT0000053 | 85 | SWP |
| SPRING TREE RIDGE | MT0004419 | 80 | GW |
| RIVERS EDGE MOBILE HOME PARK GRT FLS | MT0004687 | 75 | SWP |
| BIG STACK ESTATES | MT0004682 | 60 | SWP |
| THE FALLS MOBILE HOME COMMUNITY | MT0005077 | 60 | SWP |
| PARK GARDEN ESTATES | MT0000050 | 50 | GW |
| COBBLESTONE COURT | MT0004831 | 50 | SWP |
| SUNSET MOBILE HOME PARK | MT0000584 | 45 | GWP |
| BIG SKY MOBILE HOME PARK | MT0004683 | 40 | SWP |
| HIGH PLAINS H2O LLC | MT0005192 | 25 | SWP |
How Great Falls compares
Full Montana rankings →Great Falls's score of 34.5/100 is below the average of 48/100 among major Montana cities. 10 of 10 nearby cities score higher.
Nearby cities
View Montana rankings →About Great Falls, MT
Learn more about your water
Guides and resources related to Great Falls's water quality findings.
Explore water quality across Cascade
Frequently asked questions
Is Great Falls, MT tap water safe to drink?
Great Falls's water quality earned a grade of F (34.5/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #115 out of 115 cities tested in Montana.
What contaminants are in Great Falls's water?
Lead was measured at 12.0 ppb (90th percentile). 2 PFAS compounds were detected. 1361 violations are on record.
How is Great Falls's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Great Falls?
While lead levels are within EPA limits, a filter adds extra protection. PFAS compounds have been detected. A filter with activated carbon can help reduce exposure.
Where does Great Falls's water come from?
Great Falls's water is sourced from Surface water. The city has 27 water systems serving approximately 75,779 residents.
What health violations has Great Falls's water system had?
Great Falls has 64 health-based violations on record. The most recent violation was recorded in December 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 214 violations remain unresolved.
How does Great Falls's water compare to other cities?
Great Falls ranks #115 out of 115 cities in Montana (better than 0% of state cities) and #15564 out of 15744 cities nationally (1th percentile). The grade of F reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.