Tap Water Quality Report
Tap water quality in MISSOULA, Montana
Tap water in MISSOULA, Montana receives a grade of B (83/100) from TapWaterSafety.org. It's served by MISSOULA WATER. The most significant water quality concerns are: Arsenic significantly above health guideline; Haloacetic acids (HAA9) significantly above health guideline; Radium, combined (-226 and -228) significantly above health guideline. Data sources: EPA SDWIS, EPA ECHO, EWG Tap Water Database.
What's in MISSOULA's tap water
Top water quality concerns identified by the EPA and Environmental Working Group across the utility serving MISSOULA.
Arsenic significantly above health guideline
Moderate concernArsenic detected at 0.452 ppb, 113x above the EWG health guideline of 0.004 ppb.
Haloacetic acids (HAA9) significantly above health guideline
Moderate concernHaloacetic acids (HAA9) detected at 1.49 ppb, 25x above the EWG health guideline of 0.06 ppb.
Radium, combined (-226 and -228) significantly above health guideline
Moderate concernRadium, combined (-226 and -228) detected at 0.95 pCi/L, 19x above the EWG health guideline of 0.05 pCi/L.
EPA compliance record
Official U.S. EPA records for MISSOULA WATER (system ID MT0000294) 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 MISSOULA
Filters matched to the specific contaminants in MISSOULA's water supply.
Reverse osmosis certified for arsenic (NSF/ANSI 58)
$429-$599Reverse osmosis certified under NSF/ANSI 58 for arsenic is the most reliable home option.
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 radium (NSF/ANSI 58)
$429-$750RO certified for radium 226/228 reduces it; ion-exchange water softeners also reduce radium.
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 MISSOULA'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 |
|---|---|---|---|---|---|---|---|---|
| Arsenic Heavy metal |
0.452 ppb | 0.004 | 10.0 | 10 | 10 | 0.004 | — | 113× over |
| Haloacetic acids (HAA9) Disinfection byproduct |
1.49 ppb | 0.06 | — | — | — | — | — | 25× over |
| Radium, combined (-226 and -228) Radiological |
0.95 pCi/L | 0.05 | 5.0 | — | — | — | — | 19× over |
| Dibromoacetic acid Disinfection byproduct |
0.515 ppb | 0.03 | — | — | — | — | — | 17× over |
| Chromium (hexavalent) Heavy metal |
0.154 ppb | 0.02 | — | — | — | — | — | 7.7× over |
| Nitrate Inorganic |
0.788 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 5.6× over |
| Nitrate and nitrite Inorganic |
0.789 ppm | 0.14 | 10.0 | 11.3 | 11.3 | 10 | — | 5.6× over |
| Haloacetic acids (HAA5) Disinfection byproduct |
0.515 ppb | 0.1 | 60.0 | 60 | — | — | — | 5.2× over |
| Total trihalomethanes (TTHMs) Disinfection byproduct |
0.766 ppb | 0.15 | 80.0 | 100 | — | — | — | 5.1× over |
| Bromodichloromethane Disinfection byproduct |
0.12 ppb | 0.06 | — | — | — | — | — | 2.0× over |
| Uranium Radiological |
0.78 pCi/L | 0.43 | 20.0 | 30 | 30 | 0.43 | — | 1.8× over |
| Dibromochloromethane Disinfection byproduct |
0.163 ppb | 0.1 | — | — | — | — | — | 1.6× over |
| Chloroform Disinfection byproduct |
0.243 ppb | 0.4 | — | — | — | — | — | Below guideline |
| Barium Heavy metal |
252.6 ppb | 700.0 | 2000.0 | — | 1300 | 2000 | — | Below guideline |
| Bromoform Disinfection byproduct |
0.0757 ppb | 0.5 | — | — | — | — | — | Below guideline |
| Chlorate Disinfection byproduct |
31.1 ppb | 210.0 | — | — | — | — | — | Below guideline |
| Vanadium Other |
0.439 ppb | 21.0 | — | — | — | — | — | Below guideline |
| Manganese Heavy metal |
0.251 ppb | 100.0 | — | 50 | 80 | — | — | Below guideline |
| Molybdenum Other |
0.0426 ppb | 40.0 | — | — | — | — | — | Below guideline |
| Strontium Radiological |
0.141 ppb | 1500.0 | — | — | — | — | — | Below guideline |
| Fluoride Inorganic |
0.142 ppm | — | 4.0 | 1.5 | 1.5 | — | — | Below guideline |
| Germanium Other |
0.00674 ppb | — | — | — | — | — | — | Below guideline |
| Lithium Other |
1.55 ppb | — | — | — | — | — | — | Below guideline |
| Nitrite Inorganic |
0.000286 ppm | — | 1.0 | — | — | — | — | 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 MISSOULA WATER.