Is Eureka, MT Tap Water Safe to Drink?
Graded C- — but Copper was detected above EPA limits. Here's what's in the water and how to remove it. What to do next ↓
56.8/100
waterverge.com Eureka, MT — Water Quality Report
Eureka's drinking water received a grade of C- (56.8 out of 100), indicating poor water quality. The city's 5 water systems serve approximately 2,625 residents using surface water.
Lead levels were measured at 1.0 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 232 violations on record, including 16 health-based violations. 30 remain unresolved.
What to know about Eureka's water
Eureka ranks #69 out of 115 cities in Montana for water quality, placing it below average 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.
As a small community water system, Eureka may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
The system has seen 13 violations in the past five years, suggesting a pattern of compliance challenges that residents should monitor closely.
Water quality score
See methodology →Is Eureka, MT water safe to drink?
Eureka's drinking water has significant quality concerns based on EPA testing data. With a grade of C- (56.8/100), the system has issues across multiple categories. A water filter is recommended for all residents. The city's 5 water systems serve approximately 2,625 residents using surface water (rivers, lakes, or reservoirs).
Recent water quality updates for Eureka
A timeline of significant water quality events, violations, and data updates.
Latest EPA compliance and testing data incorporated into Eureka's water quality assessment. Grade: C- (56.8/100).
Federal disaster declaration (FEMA DR-3630). Flood event — may have impacted local water infrastructure.
Contaminants: Revised Total Coliform Rule.
Contaminants: Lead and Copper 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 Eureka's water supply.
Well within EPA limits.
Exceeds EPA action level. Copper can leach from household plumbing — flush taps for 30 seconds before drinking.
Violation history
Eureka's water system has 232 total violations on record, including 16 health-based violations. 30 remain unresolved. 13 violations were issued in the last 5 years.
Flood & environmental risk
Lincoln County has experienced 3 federally declared disasters since 1974. 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 Tobacco River At Eureka.
Where does Eureka's water come from?
Eureka's drinking water comes from surface water (rivers, lakes, or reservoirs), supplied by 5 water systems serving approximately 2,625 people. Surface water sources are more susceptible to contamination from runoff, industrial discharge, and algal blooms, requiring extensive treatment. Nearby water bodies include Tobacco River At Eureka (river).
What Eureka residents can do
Recommended: NSF-certified water filter. This addresses the specific contaminants found in Eureka'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.
Eureka'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 ↓Violation summary
Violations & advisories
Flood & disaster history
Lincoln County has experienced 3 federally declared disasters since 1974. Flooding and severe weather can compromise water treatment infrastructure and introduce contaminants into drinking water supplies.
Recommended water filters
Based on contaminants detected in Eureka'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. | 1.0 | 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. | 1.72 | 1.3 | mg/L | Inorganic | Over Limit |
Lead level trend (90th percentile)
Copper level trend (90th percentile)
See how Eureka compares by contaminant
Explore where Eureka ranks among all Montana cities for specific contaminants.
Water source & infrastructure
Where Eureka's water comes from
Eureka'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 2,625 people through 5 water systems.
Water bodies near Eureka
Eureka 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 Eureka
| System Name | PWSID | Population | Source |
|---|---|---|---|
| EUREKA TOWN OF | MT0000210 | 1,995 | SW |
| INDIAN SPRINGS RANCH SUB | MT0004611 | 455 | GW |
| BARNABY LAKE HOA | MT0003736 | 75 | GW |
| CARPENTER LAKE HOA | MT0003694 | 65 | GW |
| CREEKSIDE MOTEL RV AND TRLR PK | MT0000530 | 35 | GW |
How Eureka compares
Full Montana rankings →Eureka's score of 56.8/100 is above the average of 45/100 among major Montana cities. It outscores 9 of 10 nearby cities.
Nearby cities
View Montana rankings →About Eureka, MT
Wikipedia →Eureka is a town in Lincoln County, Montana, United States, 9 miles (14 km) south of the Canada–US border. The population was 1,380 at the 2020 census.
Learn more about your water
Guides and resources related to Eureka's water quality findings.
Explore water quality across Lincoln
Frequently asked questions
Is Eureka, MT tap water safe to drink?
Eureka's water quality earned a grade of C- (56.8/100). Significant issues have been found. A water filter is strongly recommended. The city ranks #69 out of 115 cities tested in Montana.
What contaminants are in Eureka's water?
Lead was measured at 1.0 ppb (90th percentile). 232 violations are on record.
How is Eureka'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 Eureka?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Eureka's water come from?
Eureka's water is sourced from Surface water. The city has 5 water systems serving approximately 2,625 residents.
What health violations has Eureka's water system had?
Eureka has 16 health-based violations on record. The most recent violation was recorded in November 2025. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 30 violations remain unresolved.
How does Eureka's water compare to other cities?
Eureka ranks #69 out of 115 cities in Montana (better than 40% of state cities) and #12423 out of 15744 cities nationally (21th percentile). The grade of C- reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.