Tap Water Quality Report
Tap water quality in GREAT FALLS, Montana
Tap water in GREAT FALLS, Montana receives a grade of D (66/100) from TapWaterSafety.org. It's served by GREAT FALLS CITY OF. 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. Data sources: EPA SDWIS, EPA ECHO, EWG Tap Water Database.
What's in GREAT FALLS's tap water
Top water quality concerns identified by the EPA and Environmental Working Group across the utility serving GREAT FALLS.
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.
EPA compliance record
Official U.S. EPA records for GREAT FALLS CITY OF (system ID MT0000525) for the last 3 years. Checked 2026-10-07.
Source: U.S. EPA Enforcement and Compliance History Online (ECHO), from the Safe Drinking Water Information System. See EPA's full report.
Recommended filters for GREAT FALLS
Filters matched to the specific contaminants in GREAT FALLS's water supply.
Carbon filter certified for VOCs (NSF/ANSI 53)
$180-$599Activated carbon is effective for disinfection byproducts. Look for NSF/ANSI 53 VOC reduction.
Reverse osmosis certified for arsenic (NSF/ANSI 58)
$429-$599Reverse osmosis certified under NSF/ANSI 58 for arsenic is the most reliable home option.
Disclosure: TapWaterSafety earns a commission from purchases made through these links. This does not influence our scoring methodology or filter selection.
All contaminants detected in GREAT FALLS's tap water
Every contaminant identified, compared side-by-side against US EPA legal limits, the EU Drinking Water Directive (2020/2184), WHO Guidelines, and California's Public Health Goal. 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, California OEHHA PHGs, EWG Tap Water Database.
Treatment plant contact info
For service issues, water quality concerns, or to request a Consumer Confidence Report from GREAT FALLS CITY OF.