Montana water hardness, by utility.

104 Montana utilities serving 352,369 people as they report it, from the state’s own results. Hardness is the calcium and magnesium in water; EPA sets no limit for it.

The short answer

Hard water reaches the most people here: 19 utilities serving 189,232. Another 5 utilities, serving 74,237, have water in more than one band.

The largest, City of Billings, is hard, 161 mg/L (9.4 grains per gallon).

Very hard

Above 180 mg/L (10.5 grains per gallon). 60 utilities serving 63,863 people; the 25 largest are here.

Montana utilities: very hard water
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
Kalispell Public Works	Kalispell	25,000	204	11.9
City of Columbia Falls	Columbia Falls	4,450	252	14.7
River Rock County Water and Sewer Dist	Belgrade	4,200	229	13.4
City of Shelby	Shelby	3,970	247	14.4
Lolo Water and Sewer Dist	Lolo	3,315	196	11.5
Dry Prairie Rural Water Authority	Culbertson	3,005	247	14.4
City of Colstrip	Colstrip	2,350	191	11.1
Rae Water and Sewer Dist 313	Bozeman	2,325	228	13.3
City of Malta	Malta	1,800	385	22.5
City of Choteau	Choteau	1,691	337	19.7
El Mar Estates Msla Co Water	Frenchtown	1,350	200	11.7
Valley Grove Subdivision	Bozeman	825	259	15.2
Phantom Hills Water System	Missoula	810	218	12.7
Town of Cascade	Cascade	650	237	13.9
Ptarmigan Village Inc	Whitefish	600	262	15.3
Vaughn Cascade County Water and Sewer	Vaughn	585	240	14
Gore Hill County Water Dist	Great Falls	500	726	42.4
Town of Fromberg	Fromberg	498	609	35.6
Wylie Creek Estates Subdivision	Belgrade	400	268	15.7
Stone Creek Subdivision	Billings	378	688	40.2
Sundance Subdivision	Billings	378	862	50.4
Cooke City Water District	Cooke City	300	197	11.5
Town of Ryegate	Ryegate	270	497	29.1
Country Lake Homes Whitefish	Whitefish	260	300	17.5
Granite Park Water Association	Billings	250	1060	62

All 60 with very hard water

Hard

121 to 180 mg/L (7.1 to 10.5 grains per gallon). 19 utilities serving 189,232 people, largest first.

Montana utilities: hard water
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
City of Billings	Billings	114,000	161	9.4
City of Great Falls	Great Falls	60,000	145	8.5
Lockwood Water and Sewer District	Billings	5,900	140	8.2
City of Hamilton	Hamilton	5,660	139	8.1
St Mary Headquarters and Cg	West Glacier	1,030	168	9.8
Town of Sheridan	Sheridan	632	169	9.9
Indian Springs Ranch Sub	Eureka	455	166	9.7
La Casa Grande Water and Sewer District	Helena	404	170	9.9
Roberts WUA Carbon Co Water and Sewer	Roberts	300	127	7.4
Rocky Mountain Hi Rv Park	Kalispell	275	166	9.7
Holbrook Estates	Kalispell	120	146	8.5
Lewis and Clark Trailer Court	Missoula	110	153	8.9
East Valley Estates	Kalispell	63	140	8.2
Bonnie'S Place Inc	Missoula	60	162	9.5
Sky View Estates	Kalispell	60	132	7.7
Meadowlark Mobile Home Park	Kalispell	55	172	10.1
Rosewood Acres	Kalispell	50	136	8
Hadley Road HOA	Kalispell	33	125	7.3
Woody Mountain Residential Community	Missoula	25	127	7.4

Moderately hard

61 to 120 mg/L (3.6 to 7 grains per gallon). 15 utilities serving 24,653 people, largest first.

Montana utilities: moderately hard water
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
City of Whitefish	Whitefish	10,418	70	4.1
Laurel Municipal Water System	Laurel	6,339	95	5.6
Town of Stevensville	Stevensville	2,090	114	6.6
Eastgate Village Sewer and Water	East Helena	2,000	114	6.6
Helena Leisure LLC	Helena	1,200	100	5.8
Absarokee Water and Sewer Dist	Absarokee	1,100	82	4.8
Wye Area Water System	Missoula	512	85	5
MT Moonlight Basin	Big Sky	355	84	4.9
Cinnabar the	Corwin Springs	175	69	4
Mission Mountain Lake Co W and S Dist	Ronan	118	108	6.3
Sunset West Rsid	Missoula	105	120	7
Mission Mountain View HOA	Ronan	80	106	6.2
Missoula Village West Tr CT	Missoula	68	106	6.2
Pheasant Haven Estates	Kalispell	53	120	7
Spanish Peaks Mountain Club	Big Sky	40	97	5.7

Soft

Up to 60 mg/L (3.5 grains per gallon). 5 utilities serving 384 people, largest first.

Montana utilities: soft water
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
Pondera Colony Water Systems	Valier	112	25	1.5
Hidden Lake Colony	Cut Bank	80	35	2
Arrow Creek Trailer Court	Billings	75	16	0.9
Milford Colony Inc	Wolf Creek	67	5	0.3
Turner Colony	Turner	50	1.2	0.1

Varies

Water in more than one band, depending on where or when it was sampled: each is given as its range, softest to hardest, and its report says more. 5 utilities serving 74,237 people, largest first.

Montana utilities: varies water
Utility	Based in	Serves	Hardness, mg/L	Grains per gallon
Missoula Water	Missoula	68,200	109 to 224	6.4 to 13.1
City of Polson	Polson	5,300	140 to 188	8.2 to 11
St Labre Indian School	Ashland	650	158 to 298	9.3 to 17.4
Clarks Lookout	Dillon	62	60 to 157	3.5 to 9.2
Southern Cross PUD	Anaconda	25	147 to 254	8.6 to 14.9

Source: Montana Department of Environmental Quality, Public Water Supply, 104 utilities, results from Jan. 8, 2015 to Aug. 18, 2026, read Oct. 18, 2026. Each sampling point is taken at its median; a figure is typical where every point falls in one band.

Bands are the U.S. Geological Survey’s, at 17.1 mg/L to the grain. People served is what each utility reports; where one sells water to another, the same people can be counted twice. How hardness is measured here.

Very hard

Hard

Moderately hard

Soft

Varies

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