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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
1–25 of 145City of Billings
MT0000153 · 114,000 served
Missoula Water
MT0000294 · 68,200 served
City of Great Falls
MT0000525 · 60,000 served
City of Bozeman
MT0000161 · 56,000 served
Butte Silverbow Water Dept
MT0000170 · 33,000 served
Helena Water System
MT0000241 · 32,091 served
Kalispell Public Works
MT0000259 · 25,000 served
Billings Heights Co Water Dist of
MT0000155 · 12,000 served
City of Belgrade
MT0000136 · 10,460 served
City of Whitefish
MT0000357 · 10,418 served
City of Havre
MT0000524 · 9,921 served
Town of West Yellowstone
MT0003136 · 9,899 served
City of Miles City
MT0000291 · 9,565 served
Malmstrom Air Force Base
MT0000515 · 8,850 served
Flathead County Water and Sewer
MT0001744 · 7,775 served
City of Livingston
MT0000573 · 7,500 served
Anaconda Water Department
MT0000016 · 6,750 served
Laurel Municipal Water System
MT0000270 · 6,339 served
Bigfork County Water and Sewer
MT0000262 · 6,100 served
City of Lewistown
MT0000271 · 5,923 served
Lockwood Water and Sewer District
MT0000156 · 5,900 served
City of Hamilton
MT0000234 · 5,585 served
City of Polson
MT0000308 · 5,300 served
City of Sidney
MT0000330 · 5,000 served
City of Libby
MT0000274 · 4,892 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
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Data source: Utility data from EPA SDWIS. 145 active community water systems ingested. CCR contaminant data ingestion in progress.
Last updated: 2026-04-23