01The verdict: is Choteau water safe?
Choteau's drinking water has significant quality concerns based on EPA testing data. With a grade of B- (73.9/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 3 water systems serve approximately 1,935 residents using groundwater (wells).
Copper is over its legal limit
Measured at 1.77 mg/L against the EPA Action Level of 1.3 mg/L. The ledger below shows how far over — and which filter removes it.
See the measurement ↓Lead is well under the limit
90th-percentile lead is 4.0 ppb — beneath the 15 ppb federal action level and under the 5 ppb watch threshold.
See the trend ↓5 violations in the last five years
Recent compliance history is the best predictor of future problems — the year-by-year record is below.
See the record ↓Choteau's drinking water received a grade of B- (73.9 out of 100), indicating fair water quality. The city's 3 water systems serve approximately 1,935 residents using groundwater.
Lead levels were measured at 4.0 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program. The system has 157 violations on record, including 5 health-based violations. 23 remain unresolved.
Choteau ranks #48 out of 110 cities in Montana for water quality, placing it mid-range in the state. Choteau relies on groundwater, which is generally less vulnerable to surface contamination but can be affected by naturally occurring minerals like arsenic and nitrate, as well as agricultural and industrial runoff. As a small community water system, Choteau may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
02What's in Choteau's water
Every contaminant flagged in Choteau, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
Over Limit — EPA Action Level: 1.3 mg/L
Exceeds the EPA action level. Copper leaches from household plumbing — flush taps for 30 seconds before drinking, and consider a certified filter.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. | 4.0 | 15 | ppb | Inorganic | Safe |
| 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. | 1.77 | 1.3 | mg/L | Inorganic | Over Limit |
Cities ranked by 90th-percentile lead PF PFAS in Montana
Cities ranked by compounds detected Cu Copper in Montana
Cities ranked by 90th-percentile copper
03Choteau's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. The system has 157 violations on record, including 5 health-based violations. 23 remain unresolved.
4 of the last ten years were clean. The numbered years had EPA violations — red when any were health-based, amber when they were paperwork or missed-testing issues.
▼ Down 1 ppb since 1993. Latest reading: 0 ppb (2026) — 0% of the action level. Sampled at higher-risk homes (90th percentile).
1.8mg/L(2011)
One sampling round on record — 136% of the 1.3mg/L EPA action level. Sampled at higher-risk homes (90th percentile).
04Where Choteau's water comes from
Choteau's drinking water is drawn from underground aquifers through wells.
Groundwater
Underground aquifers reached by wells — naturally filtered, but can carry minerals like arsenic and nitrate.
Local treatment
Groundwater generally needs less treatment — typically disinfection and, where needed, mineral removal.
3 systems
3 water systems, operated under local government ownership.
1,935 people
Residents served across Choteau's service area.
Groundwater is naturally filtered through rock and soil layers, generally requiring less treatment than surface water. However, it can contain naturally occurring contaminants like arsenic, radon, and minerals. Agricultural activity, septic systems, and industrial operations near well fields can introduce nitrates, pesticides, and volatile organic compounds. The system is operated by local government ownership and serves approximately 1,935 people through 3 water systems.
| System name | PWSID | Population | Source |
|---|---|---|---|
| CHOTEAU CITY OF | MT0000175 | 1,691 | Groundwater |
| NEW ROCKPORT COLONY INC | MT0001776 | 160 | Groundwater |
| MILLER COLONY | MT0001649 | 84 | Groundwater |
05Pressure on Choteau's watershed
Outside forces that shape what reaches the treatment plant. None of these is a verdict on the tap by itself — but each adds pressure worth knowing about.
Flood & storm history
3 federal disaster declarations on record for Teton County. Flooding and severe storms can overwhelm treatment plants, cause sewage overflows, and push runoff into supplies.
Drought
Teton County is in D1 (moderate drought) per the U.S. Drought Monitor (week of Jul 2026). Drought can raise disinfection-byproduct levels and taste/odor issues as utilities draw from lower reservoirs.
06How Choteau compares
Scores for nearby Montana cities on one line, with the average marked.
dashed line = Montana average (48/100)
Choteau scores 73.9/100 — above the Montana average of 48/100. It outscores 9 of 10 nearby cities. Full Montana rankings →
39.6 / 100FMissoula, MT
42.6 / 100FBozeman, MT
43.4 / 100FGreat Falls, MT
34.5 / 100FKalispell, MT
40.1 / 100FHelena, MT
39.1 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
07What to do at home
Steps matched to what testing actually found in Choteau's water — not generic advice.
Filter drinking & cooking water
NSF-certified water filter. Copper exceeds the EPA action level of 1.3 mg/L
Compare tested filters →Flush taps & check your service line
Lead leaches from pipes as water sits. Run cold water 30 seconds before drinking (especially mornings), and ask the utility whether your address still has a lead service line.
Lead risks explained →Watch for Choteau alerts
This area has a history of flood declarations — after severe weather, watch for boil-water advisories from the utility, and check the live alerts on this page.
All water alerts →Frequently asked questions
Is Choteau, MT tap water safe to drink?
Choteau's water quality earned a grade of B- (73.9/100). Some concerns have been identified. Consider a water filter for an extra layer of protection. The city ranks #48 out of 110 cities tested in Montana.
What contaminants are in Choteau's water?
Lead was measured at 4.0 ppb (90th percentile). 157 violations are on record.
How is Choteau'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 Choteau?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Choteau's water come from?
Choteau's water is sourced from Groundwater. The city has 3 water systems serving approximately 1,935 residents.
What health violations has Choteau's water system had?
Choteau has 5 health-based violations on record. The most recent violation was recorded in January 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 23 violations remain unresolved.
Is Choteau's groundwater at risk of contamination?
Choteau uses groundwater, which can be affected by naturally occurring contaminants like arsenic, radon, and nitrate, as well as agricultural runoff and industrial activity. The system has 157 violations on record that may relate to groundwater quality. Groundwater systems are generally less susceptible to surface contamination but should be monitored for emerging contaminants like PFAS.
How does Choteau's water compare to other cities?
Choteau ranks #48 out of 110 cities in Montana (better than 56% of state cities) and #9855 out of 15382 cities nationally (36th percentile). The grade of B- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.