Radon in Montana well water
In Montana, radon was detected in 100% of 339 tested private well samples.
Radon is a radioactive gas released from bedrock into well water. It escapes into household air during showers and washing, where inhaling it raises lung cancer risk. EPA has no enforceable water MCL; New Hampshire recommends treatment above 2,000 pCi/L, and many states use 4,000 pCi/L.
Check your radon number
Type the value from your lab report. It is compared to the EPA limit, the same way the full interpretation does it.
Test your Montana well for radon
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
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Getting it fixed
Book a free in-home water test with a licensed local company, or see the treatment guide for what removes radon.
Where to get a well tested for radon in Montana: certified labs, state programs and prices.
By county, from individual samples
Public monitoring samples against the EPA limit; counties with at least 30 samples.
| County | Above EPA limit | Samples | Detected | Median | Highest |
|---|---|---|---|---|---|
| Jefferson | no limit | 103 | 100% | 3,860 | 45,000 pCi/L |
| Lewis and Clark | no limit | 38 | 100% | 1,700 | 13,100 pCi/L |
| Ravalli | no limit | 63 | 100% | 1,080 | 3,700 pCi/L |
- Hamilton CCD, Ravalli County100% detected of 30
- Boulder CCD, Jefferson County100% detected of 73
- Whitehall CCD, Jefferson County100% detected of 30
Sources
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. radon counts and shares are listed on each county and town page with their sources.