Water Hardness in Montana
Across 11 measured cities — with 77 more covered by labeled county-level estimates — Montana's median tap water hardness is 159.0 mg/L (9.3 gpg): hard on the USGS scale. Below: every covered city, the state's hardest and softest water, and the geology that explains it.
Data updated September 13, 2026. Sources: utility-reported water quality data and USGS/EPA Water Quality Portal samples.
What it costs to soften Montana water
Water softener cost in Montana at 9.3 gpg prices the equipment and the installation labour against the plumber wages published for Montana, and labels every range as modelled or measured rather than leaving you to guess which it is.
Montana · 9.3 grains per gallon
$991–$1,337
installed, midpoint $1,145 — a 24,000-grain unit, the size 4 people at this hardness need.
Salt and drain water over 10 years: $864–$1,532 — the 10,183,500 grains of hardness this household removes, at the national salt price and water rate whose sources are named below. Filter changes and Service contract are omitted rather than assumed.
Sized for 4 people regenerating every 7 days: 19,530 grains of capacity needed, rounded up to the next common residential size. The median of 11 measured Montana cities in our hardness dataset. Modelled: the standard build band published for that state at the size this hardness calls for, equipment priced 2026-10-04 against the May 2025 reference period (OEWS M2025). Salt: the median retailer price of 3 retailers, read 2026-10-04, at a declared salt dose per regeneration. Drain water: about 50 gallons per regeneration from a government extension estimate read 2026-10-04, at the 2024 national average water and sewer rate from a government source read 2026-10-04.
Deciding whether it is worth it at all? Start from how much a water softener costs nationally — the same equipment, installation and ten-year ownership breakdown before any state wage adjustment is applied.
Montana Cities by Hardness Category
Measured cities only — labeled county estimates never enter the category counts or the median.
| Category | Range | Measured cities | Share |
|---|---|---|---|
| Soft | 0-60 mg/L | 0 | 0.0% |
| Moderately hard | 60-120 mg/L | 3 | 27.3% |
| Hard | 120-180 mg/L | 4 | 36.4% |
| Very hard | >180 mg/L | 4 | 36.4% |
Hardest and Softest Water in Montana
Measured values only; labeled county estimates and values under active dispute never rank.
Hardest water in Montana
Softest water in Montana
- Bozeman — 92.0 mg/L (5.4 gpg), moderately hard
- Butte — 96.9 mg/L (5.7 gpg), moderately hard
- Big Sky — 129.0 mg/L (7.5 gpg), hard
- Great Falls — 144.7 mg/L (8.5 gpg), hard
- Billings — 159.0 mg/L (9.3 gpg), hard
Every Covered City in Montana
All 88 covered Montana cities, sorted by population served. "County estimate" rows are labeled context values from USGS/EPA Water Quality Portal county sampling — they never enter the median above. City names link to each city's full water quality page.
| City | Hardness (mg/L) | gpg | Category | Data |
|---|---|---|---|---|
| Billings | 159.0 | 9.3 | Hard | Utility-reported |
| Missoula | 116.0 | 6.8 | Moderately hard | Utility-reported |
| Great Falls | 144.7 | 8.5 | Hard | Computed from Ca+Mg |
| Bozeman | 92.0 | 5.4 | Moderately hard | Utility-reported |
| Butte | 96.9 | 5.7 | Moderately hard | Utility-reported |
| Whitefish | 73.1 | 4.3 | Moderately hard | County estimate |
| Havre | 175.0 | 10.2 | Hard | County estimate |
| Belgrade | 223.0 | 13.0 | Very hard | Utility-reported |
| West Yellowstone | 134.0 | 7.8 | Hard | County estimate |
| Miles City | 326.0 | 19.1 | Very hard | County estimate |
| Anaconda | 133.0 | 7.8 | Hard | County estimate |
| Sidney | 490.6 | 28.7 | Very hard | Computed from Ca+Mg |
| Big Sky | 129.0 | 7.5 | Hard | Utility-reported |
| Box Elder | 175.0 | 10.2 | Hard | County estimate |
| Hardin | 314.0 | 18.4 | Very hard | County estimate |
| Glasgow | 353.5 | 20.7 | Very hard | County estimate |
| Poplar | 315.0 | 18.4 | Very hard | County estimate |
| Wolf Point | 315.0 | 18.4 | Very hard | County estimate |
| Deer Lodge | 161.0 | 9.4 | Hard | County estimate |
| Lolo | 201.0 | 11.8 | Very hard | Utility-reported |
| Conrad | 234.5 | 13.7 | Very hard | County estimate |
| Ronan | 99.0 | 5.8 | Moderately hard | County estimate |
| Colstrip | 179.0 | 10.5 | Hard | Computed from Ca+Mg |
| East Helena | 92.6 | 5.4 | Moderately hard | County estimate |
| Troy | 83.6 | 4.9 | Moderately hard | County estimate |
| Pablo | 99.0 | 5.8 | Moderately hard | County estimate |
| Red Lodge | 159.0 | 9.3 | Hard | County estimate |
| Townsend | 128.0 | 7.5 | Hard | County estimate |
| Eureka | 83.6 | 4.9 | Moderately hard | County estimate |
| Stevensville | 24.0 | 1.4 | Soft | County estimate |
| Thompson Falls | 86.4 | 5.0 | Moderately hard | County estimate |
| Columbus | 69.0 | 4.0 | Moderately hard | County estimate |
| Roundup | 760.0 | 44.4 | Very hard | County estimate |
| Three Forks | 134.0 | 7.8 | Hard | County estimate |
| Baker | 344.0 | 20.1 | Very hard | County estimate |
| Malta | 392.5 | 22.9 | Very hard | County estimate |
| Manhattan | 134.0 | 7.8 | Hard | County estimate |
| Plentywood | 650.0 | 38.0 | Very hard | County estimate |
| Choteau | 328.0 | 19.2 | Very hard | County estimate |
| Big Timber | 91.0 | 5.3 | Moderately hard | County estimate |
| Seeley Lake | 97.4 | 5.7 | Moderately hard | County estimate |
| Fort Benton | 221.5 | 12.9 | Very hard | County estimate |
| Virginia City | 110.0 | 6.4 | Moderately hard | County estimate |
| Boulder | 47.5 | 2.8 | Soft | County estimate |
| Chinook | 310.0 | 18.1 | Very hard | County estimate |
| Ennis | 110.0 | 6.4 | Moderately hard | County estimate |
| Philipsburg | 114.0 | 6.7 | Moderately hard | County estimate |
| Plains | 86.4 | 5.0 | Moderately hard | County estimate |
| Crow Agency | 314.0 | 18.4 | Very hard | County estimate |
| Ballantine | 163.5 | 9.6 | Hard | County estimate |
| Black Eagle | 169.0 | 9.9 | Hard | County estimate |
| Lakeside | 73.1 | 4.3 | Moderately hard | County estimate |
| Absarokee | 69.0 | 4.0 | Moderately hard | County estimate |
| Harlowton | 303.0 | 17.7 | Very hard | County estimate |
| Lincoln | 92.6 | 5.4 | Moderately hard | County estimate |
| Scobey | 286.0 | 16.7 | Very hard | County estimate |
| Fairview | 244.5 | 14.3 | Very hard | County estimate |
| White Sulphur Springs | 188.0 | 11.0 | Very hard | County estimate |
| Fort Peck | 243.6 | 14.3 | Very hard | County estimate |
| Gardiner | 60.2 | 3.5 | Moderately hard | County estimate |
| Culbertson | 315.0 | 18.4 | Very hard | County estimate |
| Circle | 243.6 | 14.3 | Very hard | County estimate |
| Medicine Lake | 650.0 | 38.0 | Very hard | County estimate |
| Lodge Grass | 314.0 | 18.4 | Very hard | County estimate |
| Broadus | 514.0 | 30.1 | Very hard | County estimate |
| Froid | 315.0 | 18.4 | Very hard | County estimate |
| Ashland | 514.0 | 30.1 | Very hard | County estimate |
| Bainville | 315.0 | 18.4 | Very hard | County estimate |
| Nashua | 353.5 | 20.7 | Very hard | County estimate |
| Ekalaka | 356.5 | 20.9 | Very hard | County estimate |
| Hysham | 227.5 | 13.3 | Very hard | County estimate |
| Kalispell | 73.1 | 4.3 | Moderately hard | County estimate |
| Hinsdale | 353.5 | 20.7 | Very hard | County estimate |
| Huntley | 260.2 | 15.2 | Very hard | Computed from Ca+Mg |
| Basin | 47.5 | 2.8 | Soft | County estimate |
| Emigrant | 60.2 | 3.5 | Moderately hard | County estimate |
| Richey | 575.0 | 33.6 | Very hard | County estimate |
| Saco | 392.5 | 22.9 | Very hard | County estimate |
| Lambert | 244.5 | 14.3 | Very hard | County estimate |
| Opheim | 353.5 | 20.7 | Very hard | County estimate |
| Ramsay | 187.0 | 10.9 | Very hard | County estimate |
| Bigfork | 99.0 | 5.8 | Moderately hard | County estimate |
| Flaxville | 286.0 | 16.7 | Very hard | County estimate |
| Terry | 245.0 | 14.3 | Very hard | County estimate |
| Florence | 24.0 | 1.4 | Soft | County estimate |
| Harlem | 310.0 | 18.1 | Very hard | County estimate |
| Martin City | 73.1 | 4.3 | Moderately hard | County estimate |
| Superior | 78.8 | 4.6 | Moderately hard | County estimate |
Above 120 mg/L (7 gpg), scale is usually worth treating — see our water softener guide, or size a system with the hardness calculator & converter.
The Geology Behind Montana's Water Hardness
Montana sits in the Mountain West basins and desert Southwest region.
Mountain snowmelt starts out soft, but across the interior West it drains into closed basins floored with carbonate and evaporite sediments, and the arid climate evaporates water faster than rain can dilute it. Rivers like the Colorado accumulate dissolved calcium and magnesium along their whole length, so the USGS maps most basin-and-range and desert-Southwest supplies as hard to very hard. Towns high in the mountains that capture snowmelt directly are the region's soft-water exceptions.
Montana Water Hardness FAQ
Does Montana have hard water?
Yes — across Montana's measured cities, typical tap water is hard. The median is 159.0 mg/L (9.3 gpg) — hard on the USGS scale, where anything above 120 mg/L (7 gpg) counts as hard. 8 of Montana's 11 measured cities fall in the hard or very hard bands (73%), so check your own city rather than the state average.
How hard is tap water in Montana?
Across the 11 Montana cities with measured values in our index, the median hardness is 159.0 mg/L (9.3 gpg) — hard on the USGS scale. Individual cities range from 92.0 to 490.6 mg/L, so check your own city rather than assuming the state number.
Which city in Montana has the hardest water?
Sidney has the hardest measured tap water in our Montana index at 490.6 mg/L (28.7 gpg) — very hard on the USGS scale. Rankings use measured utility values only; labeled county estimates and values under active dispute are excluded.
Do I need a water softener in Montana?
8 of Montana's 11 measured cities (73%) fall in the hard or very hard bands — above 120 mg/L (7 gpg), the level where most water treatment professionals suggest considering an ion-exchange softener. Hardness varies utility to utility, so look up your own city's value before sizing equipment.
How do I find my city's exact water hardness?
Enter your ZIP code in our free lookup at tapwaterdata.com/zip to see the value we hold for your Montana city from utility-reported water quality data, check your water utility's annual Consumer Confidence Report (CCR), or use a home test-strip kit.
Need whole-house or professional water treatment?
For the problems a pitcher or under-sink filter cannot fix — scale, rust and black staining, sulfur smell, well contamination, or test results you cannot explain. Tell us what is happening and we will connect you with a local water-treatment professional.
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