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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
51–75 of 145City of Townsend
MT0000344 · 2,000 served
Eastgate Village Sewer and Water
MT0001784 · 2,000 served
Town of Eureka
MT0000210 · 1,995 served
Fairmont Hot Springs Resort
MT0000589 · 1,965 served
City of Thompson Falls
MT0000341 · 1,950 served
Roundup Water Department
MT0000321 · 1,900 served
City of Three Forks
MT0000343 · 1,900 served
Town of Columbus
MT0000185 · 1,900 served
City of Baker
MT0000021 · 1,858 served
City of Malta
MT0000284 · 1,800 served
Town of Manhattan
MT0000285 · 1,800 served
Sun Prairie Village County
MT0000521 · 1,800 served
Hill County Water Districts
MT0000249 · 1,720 served
Town of Plains
MT0000305 · 1,700 served
Plentywood Water Department
MT0000306 · 1,700 served
City of Choteau
MT0000175 · 1,691 served
City of Big Timber
MT0000463 · 1,650 served
Seeley Lake Water District
MT0000327 · 1,575 served
Virginia City Water Dept
MT0000353 · 1,500 served
Town of Whitehall
MT0000359 · 1,500 served
City of Fort Benton
MT0000216 · 1,500 served
Town of Ennis
MT0000208 · 1,400 served
City of Boulder
MT0000158 · 1,400 served
Town of Philipsburg
MT0000304 · 1,360 served
El Mar Estates Msla Co Water
MT0000517 · 1,350 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