Gross alpha in well water
The county where Gross alpha is found above the limit most often is Orleans County, Vermont: 11% of 375 private wells tested, according to Vermont Tracking private well summaries.
Gross alpha is a screening test for radioactive elements in water, mainly radium and uranium from granite bedrock. A high result means one of those is present and the specific test should follow. Alpha emitters raise cancer risk when swallowed over years.
- EPA limit
- 15 pCi/L (EPA MCL for gross alpha particle activity, excluding radon and uranium (40 CFR 141.66))
- New Hampshire level
- 15 pCi/L
Where gross alpha is worst, by homeowner tests
Counties ranked by the share of private wells above the state guidance level in tests homeowners sent to the state lab. Shares combine town summaries, weighted by wells tested.
| County | Wells tested | Above state level | Highest | |
|---|---|---|---|---|
| Orleans County, Vermont | 375 | 11% | 395 pCi/L | |
| Rutland County, Vermont | 879 | 11% | 281 pCi/L | |
| Chittenden County, Vermont | 2,624 | 9% | 2,670 pCi/L | |
| Bennington County, Vermont | 280 | 7% | 295 pCi/L | |
| Franklin County, Vermont | 1,249 | 6% | 216 pCi/L | |
| Lamoille County, Vermont | 890 | 5% | 146 pCi/L | |
| Addison County, Vermont | 1,051 | 5% | 80.7 pCi/L | |
| Washington County, Vermont | 1,676 | 4% | 248 pCi/L | |
| Caledonia County, Vermont | 463 | 4% | 72.5 pCi/L | |
| Windham County, Vermont | 627 | 3% | 191 pCi/L | |
| Windsor County, Vermont | 1,295 | 2% | 45.7 pCi/L | |
| Orange County, Vermont | 714 | 2% | 40.9 pCi/L | |
| Grand Isle County, Vermont | 201 | <1% | 23.5 pCi/L |
How to test
Use a state-certified lab and a proper sampling bottle; hardware-store strips cannot measure gross alpha at the levels that matter. Collect from the kitchen tap before any treatment, and again after treatment if you install it.
How to treat
- Point-of-use reverse osmosis
- Water softener (cation exchange) for radium
- Anion exchange for uranium