Great Falls water is hard at 127 to 167 mg/L with 237 mg/L dissolved solids and chloramine, and High Plains wind keeps driving dust onto the glass.
Great Falls has drawn on the Missouri River since 1889, and its water averages 155 mg/L, hard, so rinse water left to dry marks the glass. Wind is the bigger factor in this chinook country: it drives dust onto clean panes and dries rinse water before a squeegee gets there, and the temperature can swing wildly within a day. July and August are the working months; lost wind days and the old storm windows on older homes move a quote, and a single-story exterior runs $200 to $350.
The city publishes 7.4 to 9.8 grains per gallon, about 127 to 167 mg/L, meaning treated Missouri River water leaves a light film that shows on dark frames.
| Hardness | 127–167 mg/L as CaCO₃ Averaging 155 mg/L; 7.4 to 9.8 grains per gallon, which the city classifies as moderately hard, as published by Great Falls Water Utility. |
|---|---|
| pH | 6.9–7.39 |
| Alkalinity | 92–130 mg/L as CaCO₃ |
| Manganese | 0–0.001 mg/L |
| Chloride | 14 mg/L |
| Total dissolved solids | 237 mg/L |
| Disinfectant | uv + chloramine |
| Source and treatment | Missouri River · Powdered activated carbon, coagulation, flocculation, rapid mix, sedimentation and rapid sand filtration at the Great Falls Water Treatment Facility, with ultraviolet radiation, pre-chlorination and chloramines as the residual · No softening step. |
Not in the report: corrosion index, iron and sodium.
SOURCE · City of Great Falls 2022 Consumer Confidence Report (Miscellaneous Constituents of Interest and unregulated tables), with the Public Works water treatment FAQ and the EPA SDWIS federal treatment record, PWS MT0000525 · How we source these numbers
Great Falls glass is best washed once the chinook freeze-thaw cycle has finished running meltwater across it.
MONTANA SEASON BY SEASON →Great Falls has taken its water from the Missouri River since 1889, treated at a plant sitting just above the point where the Sun River comes in. The thing that actually shapes window work here is not the river, though — it is the wind. This is chinook country, and the temperature can swing thirty or forty degrees in a day, which does more to glass than any deposit does.
The city's plant draws Missouri River water just upstream of the Sun River confluence and runs it through conventional coagulation, flocculation, sedimentation, filtration and disinfection — around four billion gallons a year, distributed through more than 300 miles of main.
That supply also serves Malmstrom Air Force Base and Black Eagle alongside the city itself, which is why the commercial and institutional book here is larger than the population alone would suggest.
River-sourced supply means seasonal variation that a well-fed city never sees. Spring runoff raises the sediment load the plant has to strip, and finished water in May does not behave identically to finished water in September even when the hardness figure is unchanged.
Giant Springs sits on the edge of town discharging on the order of 150 million gallons a day — one of the largest freshwater springs in the country, and a recurring local argument about whether the city should be drawing from it instead of the river.
Chinook winds are the defining local hazard. Warm downslope air off the Rockies can lift temperatures dozens of degrees in hours, so meltwater runs across glass in midwinter and then refreezes overnight, and the ice that forms is bonded rather than loose.
This is one of the windier cities in the country, and wind sets the working ceiling. Pole and ladder work gets abandoned more often here than in sheltered Montana towns, and blown grit reaches upper storeys that would stay clean elsewhere.
The older housing came in with the railroad and the smelter across the river, so there is a deep stock of pre-1940 stock with original double-hung sash, storm windows and painted-in glazing lines that resist any production approach.
Elevation on the high plains means strong ultraviolet exposure, which degrades insulated-unit seals faster than at sea level. Failed units fog between the panes, and no amount of cleaning fixes the complaint the customer is actually making.
Wind days lost and the pre-1940 storm windows on the older stock are what move a Great Falls quote.
Wind here takes ladders down, and failed insulated-unit seals from high-plains ultraviolet need diagnosis rather than cleaning.
OPEN COST ESTIMATOR →Nearest EPA particle monitor: 89 km
Largest air release: Calumet Montana Refining LLC., 1900 10TH ST NE (petroleum), 0.1 km outside the city limits, 84,597 lb in 2024.
In Great Falls, breaking the city's water-use restrictions, or wasting water by letting it run into avenues, streets, alleys or roadways, is a misdemeanor.
Great Falls Code §13.4.040: restriction of water use, violation, misdemeanor · checked September 2026
Great Falls defines a natural outlet to include storm sewers, then forbids discharging wastewater or other polluted water into any natural outlet without city approval and a Montana discharge permit; only stormwater and other unpolluted drainage belongs in the storm system, which rules out sending soapy rinse water down the curb inlet.
Great Falls Code 13.2.160: discharging wastewater into natural outlet · Great Falls Code 13.2.040: sewer definitions (natural outlet) · checked September 2026
Great Falls' Historic Preservation Advisory Commission is, as its name says, advisory: it inventories historic properties and works on National Register nominations but issues no permits. The Southside business overlay by downtown mainly loosens use rules, so replacing windows on a historic Great Falls building faces no local design certificate.
Great Falls Code §17.12.4.020: Historic Preservation Advisory Commission authority · Great Falls Code §17.57.010: Southside business overlay district, legislative findings · checked September 2026
High-elevation UV exposure accelerates IGU seal degradation. Document seal-degradation indicators on each residential visit. Same handling framework as Sun Valley and Park City.
The city publishes 7.4 to 9.8 grains per gallon, about 127 to 167 mg/L, meaning treated Missouri River water leaves a light film that shows on dark frames.
Residential window cleaning in Great Falls typically runs $7–11 per pane or $200–350 for a standard single-story exterior. Wind days lost and the pre-1940 storm windows on the older stock are what move a Great Falls quote.
Great Falls's drier, frost-free months are July and August, by NOAA's 1991–2020 normals for the Great Falls International Airport station, where May brings the most rain. The calendar on this page marks July (after the May 16 bloom and after smoke season). Frost nights usually run from September 24 to May 19.
Yes, if the rinse is squeegeed off before it dries: Great Falls Water Utility publishes dissolved solids of 237 mg/L, between this site's two dissolved-solids flags. Water left to dry leaves mineral scale; fresh spots lift with a mild acid. The supply is treated with uV + chloramine, which lasts in a bucket and wears deionising resin faster. It draws on Missouri River.
In Great Falls the dominant residue patterns include high plains wind-driven dust. Great Falls glass is best washed once the chinook freeze-thaw cycle has finished running meltwater across it.
Wind here takes ladders down, and failed insulated-unit seals from high-plains ultraviolet need diagnosis rather than cleaning.
Just over the Montana line