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Montana Tap Water Quality 2026

EPA drinking water data for 306 cities across Montana — covering lead levels, violation history, and compliance status.

Systems tracked: 272 Cities covered: 306 Updated: 2026 Q2
A

Montana earns an A for overall water quality

306 communities across 55 counties and 272 water systems. 97.4% have no open violations.

Median lead where detected: 2.00 ppb
27.5% of systems report lead as not detected — a state filing convention, not a water quality measure
PFAS tested at 13.4% of communities; 0 above the federal limit
Lead reported for 99.7% of communities
97.4% of communities have no open violations
Water Systems
272
Active community systems
Median Lead Level
2 ppb
13% of EPA action level
Fully Compliant
97.4%
of systems — no active violations
How we grade states Grades are based on actual EPA enforcement data — MCL violations and lead levels measured against the 15 ppb federal action level. We do not use MCLG-based detections, which are aspirational zero-tolerance goals that would make nearly every state look dangerous. Read our full methodology →

Best & Worst Cities in Montana

✓ Cleanest Water
Unionville
Lewis and Clark County
No data B
Wineglass
Park County
2.0 ppb B
Bozeman
Gallatin County
1.6 ppb A
Kalispell
Flathead County
2.0 ppb A
Evergreen
Flathead County
1.0 ppb A
Lockwood
Yellowstone County
3.0 ppb A
⚠ Needs Attention
Hinsdale
Valley County
29.0 ppb F
Crow Agency
Big Horn County
1.0 ppb F
Birney
Rosebud County
5.0 ppb D
Worden
Yellowstone County
3.0 ppb D
Pryor
Big Horn County
0.0 ppb D
Ballantine
Yellowstone County
3.0 ppb D

Water Quality by County

55 of 55
Sort:
CountySystemsLead LevelViolationsGrade
Lake County 17 2.0 ppb 0 A
Flathead County 16 2.0 ppb 0 A
Cascade County 15 2.5 ppb 0 A
Hill County 14 1.0 ppb 0 B
Missoula County 13 22.0 ppb 0 B
Gallatin County 13 2.0 ppb 0 A
Lewis and Clark County 12 2.0 ppb 0 A
Glacier County 10 3.0 ppb 0 B
Yellowstone County 10 3.0 ppb 0 B
Pondera County 9 1.0 ppb 0 A

About Montana Drinking Water

Montana is served by 272 community water systems covering 306 communities across 55 counties. 97.4% have no open violation on record.

Lead was detected in 221 communities, with a median of 2.00 ppb — 13% of the federal action level. A further 84 reported none detected. That share is a state reporting convention rather than a measure of water quality, so it is stated separately rather than averaged in.

PFAS has been tested at 13.4% of communities here, and 0 are above the limits EPA set in 2024. Coverage matters: states that test more find more, so this figure is not comparable with a state that has tested less.

Frequently Asked Questions

Is Montana tap water safe to drink? ▼
97.4% of communities have no open violation on record. No community has PFAS above the federal limit on record.
Does Montana have a lead problem? ▼
9 water systems report a 90th-percentile lead result at or above the 15 ppb action level. The action level is a treatment trigger, not a legal maximum, and 84 communities report no detection at all.
How complete is the data for Montana? ▼
Lead results are reported for 99.7% of communities and PFAS for 13.4%. Where a figure is missing it is shown as not reported rather than assumed safe.
How does Montana compare with other states? ▼
We do not rank states against each other. Lead reporting completeness ranges from under 20% to 100% depending on the state, so a national ranking would compare filing practice rather than water quality.