Water Quality Report · Updated May 12, 2026
GREAT FALLS CITY OF
GREAT FALLS CITY OF delivers tap water graded D (62/100) by TapWaterSafety.org. The utility serves approximately 60,000 residents in GREAT FALLS, Montana using surface water. The most significant water quality concerns are: Haloacetic acids (HAA9) significantly above health guideline; Arsenic significantly above health guideline; Haloacetic acids (HAA5) significantly above health guideline. For questions, the utility can be reached at 406-727-1325.
Is GREAT FALLS tap water safe to drink?
GREAT FALLS CITY OF delivers tap water that earns a grade of D (62/100) from TapWaterSafety.org — a below-average rating, with multiple concerns including haloacetic acids (haa9) significantly above health guideline.
The utility serves 60,000 residents in GREAT FALLS, drawing from surface water.
Public testing data identifies 12 contaminants in this water above EWG's health-based guidelines, including: Haloacetic acids (HAA9), Arsenic, Haloacetic acids (HAA5), Total trihalomethanes (TTHMs), Bromodichloromethane, Bromochloroacetic acid, Trichloroacetic acid, Chloroform, Dichloroacetic acid, Dibromochloromethane, Dibromoacetic acid, Chromium (hexavalent). For most residents, a properly certified home filter at the kitchen tap is the most cost-effective way to reduce exposure to whatever's in your water. See our filter recommendations below, matched specifically to this utility's contaminant profile.
Quick actions for GREAT FALLS residents
Top concerns in this water
Based on the most recent EPA and EWG data, these are the most significant water quality issues for GREAT FALLS CITY OF.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 39.1 ppb, 651x above the EWG health guideline of 0.06 ppb.
Arsenic significantly above health guideline
Moderate concernArsenic detected at 1.33 ppb, 333x above the EWG health guideline of 0.004 ppb.
Haloacetic acids (HAA5) significantly above health guideline
Moderate concernHaloacetic acids (HAA5) detected at 29.2 ppb, 292x above the EWG health guideline of 0.1 ppb.
Contact GREAT FALLS CITY OF
Reach the utility directly for service issues, water quality concerns, or to request your Consumer Confidence Report.
General Contact
Treatment Plant
Recommended water filters for GREAT FALLS
Filters matched to the specific contaminants in this water supply.
Carbon block (NSF/ANSI 42 + 53)
$40-$750Activated carbon is highly effective for disinfection byproducts like TTHM and HAA5.
Reverse Osmosis
$249-$750Arsenic is most effectively removed by reverse osmosis. Some specialized adsorptive filters also work.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
Score breakdown
This utility's overall score of 62/100 breaks down across five weighted components. Read the full methodology →
Contaminants detected — international standards comparison
Every contaminant detected, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal (the strictest US benchmark). Why we show multiple standards →
| Contaminant | Detected | EWG US health-based |
EPA US legal |
EU DWD Europe |
WHO global |
CA PHG strictest US |
Tested sample year |
Status |
|---|---|---|---|---|---|---|---|---|
| Haloacetic acids (HAA9) Disinfection byproduct |
39.1 ppb | 0.06 | — | — | — | — | — | 651× over |
| Arsenic Heavy metal |
1.33 ppb | 0.004 | 10.0 | 10 | 10 | 0.004 | — | 333× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
29.2 ppb | 0.1 | 60.0 | 60 | — | — | — | 292× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
39.3 ppb | 0.15 | 80.0 | 100 | — | — | — | 262× over |
| Bromodichloromethane Disinfection byproduct |
11.8 ppb | 0.06 | — | — | — | — | — | 196× over |
| Bromochloroacetic acid Disinfection byproduct |
3.3 ppb | 0.02 | — | — | — | — | — | 165× over |
| Trichloroacetic acid Disinfection byproduct |
15.8 ppb | 0.1 | — | — | — | — | — | 158× over |
| Chloroform Disinfection byproduct |
25.5 ppb | 0.4 | — | — | — | — | — | 64× over |
| Dichloroacetic acid Disinfection byproduct |
12.5 ppb | 0.2 | — | — | — | — | — | 63× over |
| Dibromochloromethane Disinfection byproduct |
2.09 ppb | 0.1 | — | — | — | — | — | 21× over |
| Dibromoacetic acid Disinfection byproduct |
0.431 ppb | 0.03 | — | — | — | — | — | 14× over |
| Chromium (hexavalent) Heavy metal |
0.0319 ppb | 0.02 | — | — | — | — | — | 1.6× over |
| Nitrate and nitrite Inorganic |
0.1 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | Below guideline |
| Nitrate Inorganic |
0.04 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | Below guideline |
| Aluminum Heavy metal |
53.3 ppb | 600.0 | — | 200 | — | 600 | — | Below guideline |
| Molybdenum Other |
2.29 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Vanadium Other |
1.2 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
2.8 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Monochloroacetic acid Disinfection byproduct |
0.461 ppb | 53.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.191 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| 4-Androstene-3,17-dione Other |
0.098 ppt | — | — | — | — | — | — | Below guideline |
| Fluoride Inorganic |
0.767 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
| Lithium Other |
68.9 ppb | — | — | — | — | — | — | Below guideline |
All values in the unit of the detected level. Red cells indicate the detected level exceeds that standard. Some contaminants have limits in some jurisdictions but not others (shown as —). The "Tested" column shows the year each contaminant sample was collected.
Sources: US EPA, EU Drinking Water Directive 2020/2184, WHO Guidelines (4th ed.), California OEHHA PHGs, EWG Tap Water Database.
GREAT FALLS CITY OF service area
This water system serves 1 community in Cascade County, Montana. Click any city for its dedicated tap water quality page.
Find the right filter for GREAT FALLS water
Browse filter categories by water-quality concern. Each option below is NSF-certified for the matched contaminant type.