Nitrite in Maine well water
In Maine, <1% of 31,613 private wells tested had nitrite above the Maine guideline (1 mg/L), according to Maine CDC.
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.
By county, from homeowner tests
Share of private wells above the state guidance level (1 mg/L) in tests homeowners sent to the state lab, to .
| County | Wells tested | Above state level | Highest | |
|---|---|---|---|---|
| Aroostook | 1,089 | <1% | ||
| Knox | 798 | <1% | ||
| Franklin | 938 | <1% | ||
| Somerset | 1,098 | <1% | ||
| Androscoggin | 1,542 | <1% | ||
| York | 2,518 | <1% | ||
| Penobscot | 3,018 | <1% | ||
| Kennebec | 5,244 | 0% | ||
| Cumberland | 4,301 | 0% | ||
| Hancock | 2,896 | 0% | ||
| Lincoln | 2,106 | 0% | ||
| Waldo | 1,652 | 0% | ||
| Washington | 1,422 | 0% | ||
| Oxford | 1,344 | 0% | ||
| Sagadahoc | 1,263 | 0% |
Towns with the highest share above the state level
- Hudson, Penobscot County2% of 44 wells
- Hope, Knox County2% of 45 wells
- Canaan, Somerset County2% of 62 wells
- Presque Isle, Aroostook County2% of 67 wells
- Lebanon, York County1% of 89 wells
- Jay, Franklin County<1% of 122 wells
- Greene, Androscoggin County<1% of 159 wells
- Gorham, Cumberland County0% of 493 wells
- Augusta, Kennebec County0% of 485 wells
- Ellsworth, Hancock County0% of 398 wells
- Winthrop, Kennebec County0% of 385 wells
- Brunswick, Cumberland County0% of 369 wells
- Sidney, Kennebec County0% of 341 wells
- West Gardiner, Kennebec County0% of 340 wells
- Readfield, Kennebec County0% of 326 wells
- Harpswell, Cumberland County0% of 314 wells
- Buxton, York County0% of 310 wells
- Windham, Cumberland County0% of 303 wells
- Chelsea, Kennebec County0% of 298 wells
- Monmouth, Kennebec County0% of 294 wells
- Standish, Cumberland County0% of 294 wells
- Freeport, Cumberland County0% of 282 wells
- Whitefield, Lincoln County0% of 277 wells
- Saco, York County0% of 267 wells
- Litchfield, Kennebec County0% of 265 wells
Sources
- Maine Tracking Network private well summaries: Town summaries of private well tests run by the Maine Health and Environmental Testing Laboratory, published by Maine CDC through the Maine Tracking Network. Shares are against Maine's guideline for each analyte (arsenic 10 ug/L, uranium 30 ug/L, fluoride 2 mg/L, manganese 0.3 mg/L, nitrate 10 mg/L, nitrite 1 mg/L). Towns with too few tests are suppressed (NR). Only the share above the guideline and wells tested are published; no medians. Retrieved September 3, 2026.