Montana tap water quality
850 community water systems serving 827,136 people.
Data: U.S. EPA · How we read the data · How we check it
PFAS: EPA's 2023–2025 testing. Lead: results from the last five years. 46 more systems have no recent lead results in EPA's database.
Largest water systems in Montana
- City of Billings114,000 people · Surface water · MontanaLithium above screening level
- Missoula Water68,200 people · Groundwater · MontanaLithium above screening level
- City of Great Falls60,000 people · Surface water · MontanaHaloacetic acids (HAA5) violationsAlso: Lead near 2027 level · Lithium above screening level
- City of Bozeman56,000 people · Surface water · MontanaNo PFAS above limits
- Butte Silverbow Water Dept33,000 people · Surface water · MontanaNo PFAS above limits
- Helena Water System32,091 people · Surface water · MontanaHaloacetic acids (HAA5) violationsAlso: Lithium above screening level
- Kalispell Public Works25,000 people · Groundwater · MontanaPFOS detectedAlso: PFHxS detected
- Billings Heights County Water District of12,000 people · Purchased surface water · MontanaLithium above screening level
- City of Belgrade10,460 people · Groundwater · MontanaNo PFAS above limits
- City of Whitefish10,418 people · Surface water · MontanaNo PFAS above limits
- City of Havre9,921 people · Surface water · MontanaLithium above screening levelAlso: 2 health-based violations since 2016
- Town of West Yellowstone9,899 people · Groundwater · MontanaColiform bacteria violationAlso: Lithium above screening level
- City of Miles City9,565 people · Surface water · MontanaLithium above screening levelAlso: 3 health-based violations since 2016
- Flathead County Water and Sewer9,520 people · Groundwater · MontanaNo PFAS above limits
- City of Livingston9,200 people · Groundwater · MontanaLithium above screening level
Montana cities and towns
Most health-based violations since 2016
- Town of Denton255 people · Surface water · MontanaNitrate-nitrite violation
- Fort Belknap Agency Water System2,600 people · Surface water · MontanaTotal trihalomethanes (TTHM) violations
- Town of Whitehall1,500 people · Groundwater · MontanaUranium violationsAlso: Gross alpha violations
- City of Harlem820 people · Surface water · MontanaTotal trihalomethanes (TTHM) violationsAlso: Haloacetic acids (HAA5) violations · Coliform bacteria violation
- St Labre Indian School Water System650 people · Groundwater · MontanaTotal trihalomethanes (TTHM) violations
- Beaverhead Jackson Water and Sewer District58 people · Groundwater · MontanaRadium (combined 226/228) violationsAlso: Arsenic violations
- Town of Philipsburg1,360 people · Surface water · MontanaHaloacetic acids (HAA5) violations
- King Ranch Colony Water System56 people · Groundwater · MontanaNitrate-nitrite violations
- Crow Agency Water System2,057 people · Surface water · MontanaNot in EPA's PFAS sampleAlso: 17 health-based violations since 2016
- Riverview Colony Water System130 people · Purchased surface water · MontanaHaloacetic acids (HAA5) violationsAlso: Total trihalomethanes (TTHM) violations
- Clarks Lookout Water System62 people · Groundwater · MontanaArsenic violations
- Ncmrwa Tiber Service Area200 people · Purchased surface water · MontanaHaloacetic acids (HAA5) violationsAlso: Total trihalomethanes (TTHM) violation
- Turner Colony Water System50 people · Groundwater · MontanaNitrate-nitrite violationsAlso: Coliform bacteria violations
- Richland County Valley View Wua85 people · Groundwater · MontanaTotal trihalomethanes (TTHM) violations
- Tiber County Water District750 people · Surface water · MontanaHaloacetic acids (HAA5) violationsAlso: Total trihalomethanes (TTHM) violation
All Montana utilities on this site
Every Montana system serving 50,000+ people or with PFAS above a federal limit, A to Z. Download all 850 systems as CSV.
Questions
Does Montana tap water have PFAS?
EPA tested 40 community water systems in Montana for 29 PFAS between 2023 and 2025. 2 had at least one regulated PFAS detected, and 0 had an entry-point average above a 2024 federal limit. Those 0 systems serve about 0 people. Systems have until 2029 to meet the limits.
How many Montana water systems have violations?
169 systems in Montana had at least one health-based violation since 2016 (809 violations in total). 140 violations are currently listed as unaddressed.
Which Montana water systems are over the lead action level?
6 systems had a lead 90th percentile above the 15 ppb action level in their most recent results from the last five years. Another 46 systems have no lead results in EPA's database from the last five years. Lead depends on each home's pipes, so a test of your own tap is the only way to know your level.
Source: U.S. EPA drinking water records and PFAS testing (UCMR 5). How we read the data.