Montana tap water quality
850 active community water systems.
Largest water systems
| Grade | System | People | Health violations (5y) |
|---|
| A | City of Billings | 114,000 | 0 |
| C | Missoula Water | 68,200 | 0 |
| A | City of Great Falls | 60,000 | 0 |
| A | City of Bozeman | 56,000 | 0 |
| A | Butte Silverbow Water Dept | 33,000 | 0 |
| C | Helena Water System | 32,091 | 3 |
| A | Kalispell Public Works | 25,000 | 0 |
| A | Billings Heights Co Water Dist of | 12,000 | 0 |
| A | City of Belgrade | 10,460 | 0 |
| A | City of Whitefish | 10,418 | 0 |
| C | City of Havre | 9,921 | 2 |
| A | Town of West Yellowstone | 9,899 | 0 |
| C | City of Miles City | 9,565 | 3 |
| A | Flathead County Water and Sewer | 9,520 | 0 |
| A | City of Livingston | 9,200 | 0 |
| B | Malmstrom Air Force Base | 8,850 | 0 |
| A | Anaconda Water Department | 6,750 | 0 |
| B | Laurel Municipal Water System | 6,339 | 1 |
| A | Bigfork County Water and Sewer | 6,100 | 0 |
| A | City of Lewistown | 5,923 | 0 |
| A | Lockwood Water and Sewer District | 5,900 | 0 |
| A | City of Hamilton | 5,660 | 0 |
| A | City of Polson | 5,300 | 0 |
| A | City of Sidney | 5,000 | 0 |
| D | City of Libby | 4,892 | 4 |
| A | City of Glendive | 4,873 | 0 |
| A | Town of Browning | 4,671 | 0 |
| B | City of Columbia Falls | 4,450 | 0 |
| A | North Star Zoot Water | 4,323 | 0 |
| A | City of Dillon | 4,300 | 0 |
| B | River Rock County Water and Sewer Dist | 4,200 | 0 |
| A | Big Sky County Water and Sewer Dist 363 | 4,132 | 0 |
| A | City of Shelby | 3,970 | 0 |
| A | City of Hardin | 3,500 | 0 |
| A | Lolo Water and Sewer Dist | 3,315 | 0 |
| A | City of Glasgow | 3,253 | 0 |
| A | City of Cut Bank | 3,105 | 0 |
| B | City of Poplar | 3,025 | 0 |
| A | Dry Prairie Rural Water Authority | 3,005 | 0 |
| A | City of Wolf Point | 3,000 | 0 |
| A | City of Deer Lodge | 2,900 | 0 |
| C | Lame Deer Water System | 2,605 | 2 |
| D | Fort Belknap Agency Water System | 2,600 | 30 |
| A | Conrad Water Dept | 2,500 | 0 |
| B | City of Ronan | 2,483 | 0 |
| B | Big Mountain Water Company | 2,435 | 0 |
| C | City of Colstrip | 2,350 | 2 |
| A | Rae Water and Sewer Dist 313 | 2,325 | 0 |
| A | City of Forsyth | 2,260 | 0 |
| C | Pablo Lake County Water and Sewer Dist | 2,175 | 2 |
Most issues (systems serving 10,000+)
C3 health-based violations in the last 5 years; PFAS tested (UCMR 5), none above federal limits; Lead 90th percentile below the action level (2024).
CNo health-based violations in the last 5 years; PFAS tested (UCMR 5), none above federal limits; Lead 90th percentile ABOVE the action level (2023).
ANo health-based violations in the last 5 years; 4 monitoring/reporting violations; PFAS tested (UCMR 5), none above federal limits; Lead 90th percentile below the action level (2024).
ANo health-based violations in the last 5 years; 3 monitoring/reporting violations; PFAS tested (UCMR 5), none above federal limits; Lead 90th percentile below the action level (2024).
ANo health-based violations in the last 5 years; PFAS tested (UCMR 5), none above federal limits; Lead 90th percentile below the action level (2023).
ANo health-based violations in the last 5 years; PFAS tested (UCMR 5), none above federal limits; Lead 90th percentile above the new 10 ppb action level (LCRI, effective Nov 1, 2027); Lead 90th percentile below the action level (2026).
ANo health-based violations in the last 5 years; PFAS tested (UCMR 5), none above federal limits; Lead 90th percentile below the action level (2025).
ANo health-based violations in the last 5 years; PFAS tested (UCMR 5), none above federal limits; Lead 90th percentile below the action level (2023).
ANo health-based violations in the last 5 years; PFAS tested (UCMR 5), none above federal limits; Lead 90th percentile below the action level (2025).
ANo health-based violations in the last 5 years; PFAS tested (UCMR 5), none above federal limits; Lead 90th percentile below the action level (2025).
Cities
AbsarokeeActonAlbertonAnacondaAntelopeArleeAshlandAugustaBabbBainvilleBakerBallantineBasinBearcreekBelfryBelgradeBeltBig ArmBig SandyBig SkyBig TimberBigforkBigfork - Lake CoBillingsBirneyBlack EagleBonnerBoulderBox ElderBozemanBradyBridgerBroadusBroadviewBrocktonBrowningBusbyButteBynumCarterCascadeCharloChesterChinookChoteauCircleClancyClintonClyde ParkCoffee CreekColstripColumbia FallsColumbusConradCooke CityCoramCorvallisCorwin SpringsCraneCulbertsonCusterCut BankDarbyDaytonDeer LodgeDellDentonDillonDivideDixonDodsonDrummondDupuyerDuttonEast Glacier ParkEast HelenaEkalakaElmoEmigrantEnnisEthridgeEurekaFairfieldFairviewFlaxvilleFlorenceForest GroveForsythFort BentonFort HarrisonFort PeckFort SmithFortineFrazerFrenchtownFroidFrombergGalataGallatin GatewayGardinerGarryowenGeraldineGeyserGildfordGlasgowGlenGlendiveGrass RangeGreat FallsGreycliffHamiltonHardinHarlemHarlowtonHauganHavreHaysHeart ButteHelenaHeronHighwoodHinghamHinsdaleHobsonHot SpringsHungry HorseHuntleyHusonHyshamJacksonJefferson CityJolietJoplinJordanJudith GapKalispellKevinKilaLakesideLambertLame DeerLaurelLedgerLewistownLibbyLimaLincolnLivingstonLodge GrassLoloLomaLonepineLoringLothairMaltaManhattanMarionMartin CityMartinsdaleMarysvilleMedicine LakeMelstoneMiles CityMilltownMissoulaMoccasinMonarchMooreMusselshellNashuaNeihartNorrisNoxonOpheimOutlookPabloParadisePendroyPhilipsburgPinesdalePlainsPlentywoodPlevnaPolsonPoplarPowerPrayPryorRamsayRapeljeRavalliRed LodgeReed PointRexfordRicheyRobertsRollinsRonanRoundupRoyRudyardRyegateSacoSaint IgnatiusSaint MarieSaint RegisSand CouleeSanta RitaScobeySeeley LakeShawmutShelbyShepherdSheridanSidneySilver GateSimmsSomersSt IgnatiusSt MarieSt RegisStanfordStevensvilleStockettStrykerSun RiverSunburstSuperiorSweet GrassSweetgrassThompson FallsThree ForksTownsendTrout CreekTroyTurnerTwin BridgesTwo DotUlmValierVaughnVirginia CityWarm SpringsWest GlacierWest YellowstoneWestbyWhite Sulphur SpringsWhitefishWhitehallWhitewaterWhitlashWibauxWilsallWinifredWinnettWolf CreekWolf PointWordenWyolaZortman