Drinking water / MT
PFAS in Montana drinking water
45 Montana public water systems tested under UCMR5. 5 detected at least one PFAS compound; 40 detected none at the reporting thresholds. Values are the highest single result per compound, in ng/L (parts per trillion). The federal limit for PFOA and PFOS is 4 ng/L.
| Water system | Serves | Highest results (ng/L) | Reading |
|---|---|---|---|
| ALPINE VILLAGE WUA MT0003229 | Flathead | PFOS 4.1 * | above final limit |
| KALISPELL PUBLIC WORKS MT0000259 | Flathead | PFOS 6.6 *PFHxS 5 | above final limit |
| BIG SKY COUNTY WATER AND SEWER DIST 363 MT0002385 | Madison | PFBS 3.1 | detected |
| HAMILTON CITY OF MT0000234 | Ravalli | PFBS 3.1 | detected |
| MALMSTROM AIR FORCE BASE MT0000515 | Cascade | PFBA 7 | detected |
* exceeds the final federal MCL for that compound. Detections of compounds whose limits EPA proposed to rescind in May 2026 are shown for information.
Systems with no PFAS detected
40 tested systems reported no PFAS above the laboratory reporting limits. Each has its own page with its sampling detail.
- ANACONDA WATER DEPARTMENT
- BELGRADE CITY OF
- BIG PINES TRAILER COURT
- BIGFORK COUNTY WATER AND SEWER
- BILLINGS CITY OF
- BLACK ROCK ESTATES SUBDIVISION
- BOZEMAN CITY OF
- BUTTE SILVERBOW WATER DEPT
- CO WATER DIST OF BILLINGS HEIGHTS
- COLUMBIA FALLS CITY OF
- CULLIGAN WATER CONDITIONING GREAT FALLS
- DILLON CITY OF
- FAIRFIELD TOWN OF
- FLATHEAD COUNTY WATER AND SEWER
- FRENCHTOWN HIGH SCHOOL
- GLENDIVE CITY OF
- GREAT FALLS CITY OF
- HARDIN CITY OF
- HAVRE CITY OF
- HELENA WATER SYSTEM
- LAUREL MUNICIPAL WATER SYSTEM
- LEWISTOWN CITY OF
- LIBBY CITY OF
- LIVINGSTON CITY OF
- LOCKWOOD WATER AND SEWER DISTRICT
- MILES CITY CITY OF
- MISSOULA WATER
- MONTANA STATE UNIVERSITY BILLINGS
- MONTANA STATE UNIVERSITY BOZEMAN
- PHANTOM HILLS WATER SYSTEM
- PINESDALE TOWN OF
- POLSON CITY OF
- RIVER ROCK COUNTY WATER AND SEWER DIST
- ROCKY MOUNTAIN COLLEGE
- SHELBY CITY OF
- SIDNEY CITY OF
- SUN PRAIRIE VILLAGE COUNTY
- UNIVERSITY OF MONTANA
- WEST YELLOWSTONE TOWN OF
- WHITEFISH CITY OF
A detection at the system level does not tell you what reaches one specific tap: levels vary by entry point, treatment train and plumbing. A certified lab test of your own tap settles it. Testing and treatment options