Water hardness in Great Falls
8.5 gpg hard
Tap water in Great Falls is hard: 8.5 gpg (145 mg/L · 8.1 °dH · 14.5 °fH).
Source: City of Great Falls 2025 Consumer Confidence Report (2025) · data checked 2026-10-23
Great Falls treats Missouri River water at its own plant, just upstream of the Sun River confluence, as it has for well over a century. River water in this part of Montana picks up carbonate from limestone, so the water is hard at 145 mg/L CaCO₃. Scale builds up in kettles and heaters.
USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
Water data
| Total hardness | 8.5 gpg |
|---|---|
| Calcium (mg/L) | 37 |
| Magnesium (mg/L) | 13 |
| Utility | City of Great Falls Public Works (own water treatment) |
How Great Falls compares
- Tap water in Great Falls is 6 % softer than the median of the 1372 cities we track in the United States (9.1 gpg).
- By hardness it ranks 742 of 1372 in the United States (1 = hardest); 46 % of these cities have softer water.
- In Montana it is number 2 of 4 cities; the regional median is 8 gpg.
Ranking of the hardest and softest water in the United States →
What it means at home
- Fast scale on taps, shower screens and kettle; white spots on glassware.
- Water heater: efficiency loss and element failures within years if unprotected.
- Dry skin and dull hair after showering are common.
- Softener recommended; jug or reverse osmosis for drinking.
How much salt will you use for softening?
Recommended, especially with a heater or boiler: scale cuts efficiency and shortens its life.
Descale a coffee machine or kettle about every 2 months (typical manufacturer guidance for this hardness).
Estimates for planning, not a quote. Check your appliance manual for exact settings.
Dishwasher setting in Great Falls
| Brand | Setting for this water |
|---|---|
| Bosch | H01 |
| Miele | 8 °dH |
| AEG / Electrolux | 2 |
| Beko | 3rd |
| Hoover | S1 |
| LG | H2 |
From each brand's manual for the model family named in the source; your model may differ, so check its manual. All brands and how to change the setting →
FAQ
Is Great Falls water hard or soft?
It is hard: 145 mg/L as CaCO₃ (8.5 gpg, 8.1 °dH). The usual bands are soft < 60, moderately hard 60–120, hard 120–180 and very hard > 180 mg/L.
Is tap water in Great Falls safe to drink?
Hardness is not a health issue; it is about limescale, taste and appliances. Mains water must meet national drinking-water standards. USGS classes: soft 0–60, moderately hard 61–120, hard 121–180, very hard >180 mg/L.
How many grains per gallon is Great Falls water?
8.5 gpg, equal to 8.1 °dH, 14.5 °fH or 145 mg/L calcium carbonate.
What dishwasher salt setting should I use in Great Falls?
For 145 mg/L (8.1 °dH) check your manufacturer's table: level 4–5.
Do I need a water softener in Great Falls?
Recommended if you have a water heater, boiler or tankless unit: it saves repairs and detergent.
Source
Source: City of Great Falls 2025 Consumer Confidence Report (2025). Method: figure published by the water supplier. City of Great Falls 2025 Consumer Confidence Report · Outdated figure? Tell us