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Montana Water Quality
145
Utilities in database
0.7M
Residents served
48%
On private wells
2
Key contaminants tracked
Drinking Water in Montana
Montana has 145 community water systems serving approximately 0.7 million residents. Primary water sources include groundwater. The most commonly reported contaminants include disinfection byproducts, nitrates. 48% of Montana residents rely on private wells. MDEQ holds primary enforcement authority under the Safe Drinking Water Act.
Utilities in Montana
76–100 of 145City of Chinook
MT0000174 · 1,300 served
Va Medical Center Helena
MT0000246 · 1,275 served
Black Eagle Cascade County Water Sewer
MT0000157 · 1,233 served
Lakeside Water System
MT0000266 · 1,225 served
Forest Park Water Rsid 24
MT0000233 · 1,200 served
Helena Leisure Llc
MT0000590 · 1,200 served
Hungry Horse Co Water and Sewer District
MT0000253 · 1,135 served
Town of Superior
MT0000339 · 1,100 served
Absarokee Water and Sewer Dist
MT0000003 · 1,100 served
Cmrwa Musselshell Judith Rural Water Sys
MT0005109 · 1,100 served
City of Harlowton
MT0000240 · 1,050 served
St Mary Headquarters and Cg
MT0002729 · 1,030 served
City of Scobey
MT0000326 · 1,026 served
City of White Sulphur Springs
MT0000360 · 1,000 served
Prairie Water Company
MT0003539 · 1,000 served
Town of Fairview
MT0000213 · 1,000 served
Meadow Lake Co Water and Sewer District
MT0000914 · 950 served
Westview Mobile Home Park
MT0000437 · 947 served
Pioneer Water Service
MT0004226 · 900 served
Town of Chester
MT0000173 · 870 served
Town of Darby
MT0000195 · 850 served
Valley Grove Subdivision
MT0003780 · 825 served
City of Harlem
MT0000239 · 820 served
Phantom Hills Water System
MT0004379 · 810 served
Worden Ballantine Yellowstone
MT0000022 · 800 served
Key Contaminant Concerns in Montana
Nitrates
Nitrate (NO₃⁻) is a nitrogen-containing compound that forms naturally through the decomposition of organic matter. At elevated concentrations — almost always from human activity — nitrate interferes with the blood's ability to carry oxygen. The United States produces over 23 million tons of nitrogen fertilizer annually, making agricultural runoff the dominant source of nitrate contamination.
DBPs
When utilities add chlorine to water to kill pathogens, it reacts with dissolved organic matter — leaves, algae, soil — to produce disinfection byproducts (DBPs). Over 600 DBPs have been identified. The EPA regulates two groups: total trihalomethanes (TTHMs, including chloroform) and haloacetic acids (HAA5). DBP levels tend to be highest in surface water systems and in warm months when organic matter is elevated.
Montana Water FAQs
Quick Links
Data source: Utility data from EPA SDWIS. 145 active community water systems ingested. CCR contaminant data ingestion in progress.
Last updated: 2026-04-23