PFNA in well water
PFNA is a long-chain forever chemical found near industrial sites and firefighting foam. It is linked to immune and developmental effects and high cholesterol. New Hampshire set its own limit in 2019.
- EPA limit
- 10 ng/L (EPA MCL (2024 PFAS rule; proposed for rescission May 2026); New Hampshire MCL is 11 ng/L)
- CAS number
- 375-95-1
By individual samples
Counties with at least 30 individual samples in public monitoring data, against the EPA limit.
| County | Samples | Detected | Above EPA limit | Median |
|---|---|---|---|---|
| Somerset County, Maine | 580 | 41% | 7% | 0 ng/L |
| Kennebec County, Maine | 450 | 21% | 4% | 0 ng/L |
| Waldo County, Maine | 401 | 13% | 3% | 0 ng/L |
| Lincoln County, Maine | 110 | 24% | <1% | 0 ng/L |
| Penobscot County, Maine | 294 | 12% | <1% | 0 ng/L |
| York County, Maine | 385 | 6% | <1% | 0 ng/L |
| Hillsborough County, New Hampshire | 3,644 | 22% | <1% | 0 ng/L |
| Rockingham County, New Hampshire | 2,095 | 23% | 0% | 0 ng/L |
| Washington County, Maine | 36 | 17% | 0% | 0 ng/L |
| Knox County, Maine | 36 | 11% | 0% | 0 ng/L |
| Hancock County, Maine | 58 | 10% | 0% | 0 ng/L |
| Aroostook County, Maine | 113 | 9% | 0% | 0 ng/L |
| Cumberland County, Maine | 573 | 9% | 0% | 0 ng/L |
| Piscataquis County, Maine | 30 | 7% | 0% | 0 ng/L |
| Strafford County, New Hampshire | 157 | 6% | 0% | 0 ng/L |
How to test
Use a state-certified lab and a proper sampling bottle; hardware-store strips cannot measure pfna at the levels that matter. Collect from the kitchen tap before any treatment, and again after treatment if you install it.
How to treat
- Granular activated carbon whole-house
- Point-of-use reverse osmosis
- Anion exchange