Nitrite in well water
The county where Nitrite is found above the limit most often is Aroostook County, Maine: <1% of 1,089 private wells tested, according to Maine Tracking Network private well summaries.
Nitrite is the short-lived form of nitrogen from septic systems and fertilizer. It causes the same infant blood disorder as nitrate at a tenth of the concentration, and usually points to fresh contamination.
- EPA limit
- 1 mg/L (EPA MCL as nitrogen (40 CFR 141.62))
- New Hampshire level
- 1 mg/L
- CAS number
- 14797-65-0
Where nitrite 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 | |
|---|---|---|---|---|
| Aroostook County, Maine | 1,089 | <1% | ||
| Sullivan County, New Hampshire | 733 | <1% | 1.8 mg/L | |
| Knox County, Maine | 798 | <1% | ||
| Franklin County, Maine | 938 | <1% | ||
| Somerset County, Maine | 1,098 | <1% | ||
| Androscoggin County, Maine | 1,542 | <1% | ||
| York County, Maine | 2,518 | <1% | ||
| Penobscot County, Maine | 3,018 | <1% | ||
| Kennebec County, Maine | 5,244 | 0% | ||
| Merrimack County, New Hampshire | 4,873 | 0% | 0.5 mg/L | |
| Cumberland County, Maine | 4,301 | 0% | ||
| Hancock County, Maine | 2,896 | 0% | ||
| Grafton County, New Hampshire | 2,686 | 0% | 0.4 mg/L | |
| Rockingham County, New Hampshire | 2,332 | 0% | 0.5 mg/L | |
| Hillsborough County, New Hampshire | 2,118 | 0% | 0.8 mg/L |
How to test
Use a state-certified lab and a proper sampling bottle; hardware-store strips cannot measure nitrite 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
- Anion exchange
- Distillation