Fluoride in Idaho well water
In Idaho, 1% of 8,495 tested private well samples exceeded the EPA limit for fluoride (4 mg/L).
Natural fluoride in bedrock wells can exceed the limit. Above 4 mg/L long-term exposure causes skeletal fluorosis; above 2 mg/L children can develop tooth mottling.
Check your fluoride number
Type the value from your lab report. It is compared to the EPA limit, the same way the full interpretation does it.
Getting it fixed
Book a free in-home water test with a licensed local company, or see the treatment guide for what removes fluoride.
By county, from individual samples
Public monitoring samples against the EPA limit (4 mg/L); counties with at least 30 samples.
| County | Samples | Detected | Above EPA limit | Median | Highest |
|---|---|---|---|---|---|
| Boise | 99 | 85% | 23% | 1.34 | 13 mg/L |
| Owyhee | 176 | 96% | 18% | 0.9 | 20 mg/L |
| Franklin | 61 | 95% | 10% | 0.38 | 6.4 mg/L |
| Lemhi | 119 | 85% | 6% | 0.217 | 11 mg/L |
| Twin Falls | 570 | 99% | 4% | 0.7 | 32.5 mg/L |
| Custer | 96 | 74% | 2% | 0.201 | 6.71 mg/L |
| Elmore | 275 | 92% | 1% | 0.42 | 9.8 mg/L |
| Bannock | 325 | 78% | <1% | 0.2 | 4.82 mg/L |
| Gooding | 128 | 99% | <1% | 0.4 | 4.82 mg/L |
| Power | 171 | 92% | <1% | 0.45 | 75.9 mg/L |
| Fremont | 225 | 94% | <1% | 0.645 | 6.98 mg/L |
| Canyon | 1,032 | 95% | <1% | 0.478 | 16 mg/L |
| Bingham | 249 | 100% | 0% | 0.525 | 1 mg/L |
| Madison | 125 | 100% | 0% | 0.41 | 2.98 mg/L |
| Jerome | 153 | 99% | 0% | 0.5 | 0.7 mg/L |
- Bruneau CCD, Owyhee County43% of 37
- Grand View CCD, Owyhee County30% of 54
- Garden Valley CCD, Boise County22% of 37
- Buhl CCD, Twin Falls County15% of 117
- Salmon CCD, Lemhi County13% of 54
- Inkom CCD, Bannock County9% of 34
- West Salmon Falls CCD, Twin Falls County6% of 50
- Glenns Ferry CCD, Elmore County5% of 63
- Challis CCD, Custer County5% of 44
- Huston CCD, Canyon County1% of 73
- Ashton CCD, Fremont County1% of 74
- American Falls CCD, Power County<1% of 113
- Twin Falls CCD, Twin Falls County0% of 63
- Nezperce CCD, Lewis County0% of 31
- Wilder CCD, Canyon County0% of 123
- Cottonwood CCD, Idaho County0% of 34
- Filer CCD, Twin Falls County0% of 90
- St. Anthony CCD, Fremont County0% of 55
- Fort Hall CCD, Bannock County0% of 38
- Declo CCD, Cassia County0% of 42
Sources
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. fluoride counts and shares are listed on each county and town page with their sources.