States → Montana
State profile · EPA SDWIS + UCMR5
Montana Drinking Water Quality
2,263 public water systems serve 1,112,267 people across Montana, with every Safe Drinking Water Act violation and UCMR5 PFAS result on record.
- 2,263
- Water systems
- 297,270
- Total violations
- 94.7%
- Systems w/ a violation
- 62.2%
- PFAS detection rate
The verdict
Across Montana, 2,144 of 2,263 water systems (94.7%) carry at least one EPA violation, and 28 of 45 UCMR5-tested systems show PFAS.
- 297,270
- Total EPA violations on record
- 9%
- Health-based (MCL / treatment)
- 94.7%
- Systems with ≥1 violation
- 62.2%
- UCMR5 PFAS detection rate
Water Systems
2,263
Total Violations
297,270
Violation Rate
94.7%
PFAS Detection
62.2%
28 of 45 tested
Violation Composition
How Montana's 297,270 violations break down by type, per EPA SDWIS classification.
Health-based (25,922) Monitoring/Reporting (271,348)
| Metric | Value | Share |
|---|---|---|
| Public water systems | 2,263 | - |
| Population served | 1,112,267 | - |
| Total violations | 297,270 | 100% |
| Health-based violations | 25,922 | 8.7% |
| Systems with violations | 2,144 | 94.7% |
| PFAS detection rate | 28 of 45 | 62.2% |
Health-based violations indicate the contaminant exceeded an EPA Maximum Contaminant Level (MCL) or treatment-technique requirement. Monitoring/reporting violations indicate procedural issues (missed tests, late reports) - not necessarily a contamination event.
Largest Water Systems
Billings City Of
Billings, MT · 114,000 served
Missoula Water
Missoula, MT · 68,200 served
Great Falls City Of
Great Falls, MT · 60,000 served
Bozeman City Of
Bozeman, MT · 56,000 served
Butte Silverbow Water Dept
Butte, MT · 33,000 served
Helena Water System
Helena, MT · 32,091 served
Kalispell Public Works
Kalispell, MT · 25,000 served
Montana State University Bozeman
Bozeman, MT · 19,200 served
University of Montana
Missoula, MT · 15,000 served
Co Water Dist of Billings Heights
Billings, MT · 12,000 served
Belgrade City Of
Belgrade, MT · 10,460 served
Whitefish City Of
Whitefish, MT · 10,418 served
Havre City Of
Havre, MT · 9,921 served
West Yellowstone Town Of
West Yellowstone, MT · 9,899 served
Miles City City Of
Miles City, MT · 9,565 served
Malmstrom Air Force Base
Malmstrom Air Force Base, MT · 8,850 served
Flathead County Water and Sewer
Kalispell, MT · 7,775 served
Livingston City Of
Livingston, MT · 7,500 served
Anaconda Water Department
Anaconda, MT · 6,750 served
Laurel Municipal Water System
Laurel, MT · 6,339 served
Most Violations
#1 Malta City Of Malta
3,072 #2 Helena RV and Mobile Home Park Hailey
2,806 #3 Westview Mobile Home Park Missoula
2,111 #4 Springhill Park Subdivision Bozeman
1,959 #5 Brady County Water Sewer District Brady
1,954 #6 Clyde Park Water Dept Clyde Park
1,877 #7 St Charles School Ashland
1,793 #8 Pleasant Park Community Inc Great Falls
1,791 #9 Forest Park Water Rsid 24 Glendive
1,742 #10 Rivershore Community LLC Port Orchard
1,698 #11 White Sulphur Springs City Of White Sulphur Springs
1,611 #12 Bitterroot Gateway Mb Pk Lolo Lolo
1,600 #13 Pine Crest Tr Pk Campbell
1,574 #14 Bearcreek Municipal Water Sys Red Lodge
1,555 #15 St Labre Indian School Ashland
1,488 Counties in Montana
Yellowstone
116 systems · 168,956 served
· 16,006 violations
Gallatin
207 systems · 147,444 served
· 30,683 violations
Missoula
243 systems · 138,758 served
· 31,553 violations
Flathead
324 systems · 105,538 served
· 20,270 violations
Cascade
98 systems · 96,521 served
· 15,613 violations
Lewis and Clark
162 systems · 67,948 served
· 24,270 violations
Silver Bow
23 systems · 42,630 served
· 2,525 violations
Ravalli
129 systems · 30,657 served
· 9,816 violations
Lake
91 systems · 19,815 served
· 7,834 violations
Lincoln
91 systems · 19,119 served
· 7,279 violations
Mineral
37 systems · 16,697 served
· 1,421 violations
Park
58 systems · 15,803 served
· 12,317 violations
Hill
16 systems · 14,962 served
· 2,905 violations
Madison
45 systems · 14,392 served
· 4,771 violations
Fergus
20 systems · 11,162 served
· 4,498 violations
Glacier
27 systems · 10,757 served
· 3,989 violations
Custer
11 systems · 10,579 served
· 431 violations
Dawson
32 systems · 10,547 served
· 6,707 violations
Big Horn
23 systems · 10,335 served
· 6,556 violations
Jefferson
42 systems · 10,086 served
· 6,871 violations
Deer Lodge
15 systems · 9,563 served
· 2,034 violations
Beaverhead
48 systems · 9,494 served
· 6,629 violations
Broadwater
20 systems · 9,301 served
· 3,084 violations
Sanders
44 systems · 9,212 served
· 3,111 violations
Carbon
36 systems · 9,108 served
· 5,566 violations
Stillwater
31 systems · 8,417 served
· 5,741 violations
Granite
21 systems · 7,984 served
· 2,193 violations
Rosebud
15 systems · 7,415 served
· 3,651 violations
Sweet Grass
15 systems · 7,279 served
· 1,071 violations
Richland
16 systems · 7,074 served
· 4,453 violations
Showing top 30 of 56 counties.
Drinking Water Guides
Frequently Asked Questions
How many water systems are in Montana? ▼
Montana has 2,263 public water systems serving approximately 1,112,267 people. These include community water systems, non-transient non-community systems, and transient non-community systems regulated under the Safe Drinking Water Act.
How many drinking water violations are in Montana? ▼
Montana has 297,270 total drinking water violations on record, with 25,922 classified as health-based violations. 94.7% of water systems in the state have at least one violation.
Has PFAS been found in Montana drinking water? ▼
Of 45 water systems tested for PFAS in Montana, 28 had PFAS detected, a 62.2% detection rate. PFAS are persistent "forever chemicals" that do not break down in the environment.
What is the violation rate for Montana water systems? ▼
Montana's violation rate is 94.7%. This measures the percentage of public water systems that have at least one recorded violation in the EPA SDWIS database, including both health-based and monitoring/reporting violations.
Where does this Montana water data come from? ▼
All drinking water data comes from the EPA Safe Drinking Water Information System (SDWIS) and the UCMR5 PFAS monitoring program. SDWIS is the federal database that tracks compliance for all public water systems regulated under the Safe Drinking Water Act.
Data Sources & Methodology
Drinking water violation data from the EPA Safe Drinking Water Information System (SDWIS). PFAS testing data from the UCMR5 monitoring program. SDWIS tracks all public water systems regulated under the Safe Drinking Water Act.
Read our methodology - how this data is sourced, computed, and verified.
Related
Data sourced from EPA SDWIS and UCMR5 PFAS monitoring data. See our methodology for details. Retrieved and formatted by PlainWater Editorial
Every figure on PlainWater is rendered directly from EPA SDWIS drinking-water data, no number is typed in by an editor. This page draws directly on EPA SDWIS data, no figure is typed in by an editor. See our editorial standards & corrections policy, the methodology behind these numbers, or report a data error.