State Hub
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
26–50 of 145City of Glendive
MT0000229 · 4,873 served
City of Columbia Falls
MT0000181 · 4,450 served
North Star Zoot Water
MT0004284 · 4,323 served
City of Dillon
MT0000201 · 4,300 served
River Rock County Water and Sewer Dist
MT0004082 · 4,200 served
Big Sky County Water and Sewer Dist 363
MT0002385 · 4,132 served
City of Shelby
MT0000328 · 3,970 served
City of Hardin
MT0000235 · 3,500 served
Lolo Water and Sewer Dist
MT0000278 · 3,315 served
City of Glasgow
MT0000415 · 3,253 served
City of Cut Bank
MT0000193 · 3,105 served
Dry Prairie Rural Water Authority
MT0004348 · 3,005 served
City of Deer Lodge
MT0000197 · 2,900 served
Conrad Water Dept
MT0000186 · 2,500 served
City of Ronan
MT0000318 · 2,483 served
Big Mountain Water Company
MT0000060 · 2,435 served
City of Colstrip
MT0000180 · 2,350 served
Rae Water and Sewer Dist 313
MT0000628 · 2,325 served
City of Forsyth
MT0000215 · 2,260 served
Pablo Lake County Water and Sewer Dist
MT0001917 · 2,175 served
City of East Helena
MT0000196 · 2,114 served
City of Troy
MT0000348 · 2,100 served
Montana State Prison
MT0000198 · 2,100 served
Town of Stevensville
MT0000335 · 2,090 served
City of Townsend
MT0000344 · 2,000 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