Manganese in Maine well water
In Maine, 5% of 25,764 private wells tested had manganese above the Maine guideline (300 ug/L), according to Maine CDC.
Manganese stains fixtures and laundry above 50 ug/L. EPA's health advisory is 300 ug/L; infants are the most sensitive, and newer research links elevated manganese to neurological effects in children. It is one of the most common private well problems in New England.
By county, from homeowner tests
Share of private wells above the state guidance level (300 ug/L) in tests homeowners sent to the state lab, to .
| County | Wells tested | Above state level | Highest | |
|---|---|---|---|---|
| Sagadahoc | 1,008 | 9% | ||
| Knox | 633 | 8% | ||
| Lincoln | 1,691 | 7% | ||
| Hancock | 2,494 | 6% | ||
| Washington | 1,160 | 6% | ||
| Piscataquis | 307 | 5% | ||
| Waldo | 1,356 | 5% | ||
| York | 1,968 | 5% | ||
| Cumberland | 3,513 | 5% | ||
| Penobscot | 2,436 | 4% | ||
| Kennebec | 4,407 | 4% | ||
| Oxford | 1,076 | 4% | ||
| Franklin | 765 | 4% | ||
| Somerset | 900 | 3% | ||
| Androscoggin | 1,190 | 2% |
Towns with the highest share above the state level
- Georgetown, Sagadahoc County28% of 79 wells
- Harpswell, Cumberland County23% of 252 wells
- South Bristol, Lincoln County19% of 80 wells
- Danforth, Washington County18% of 33 wells
- Westport Island, Lincoln County17% of 58 wells
- West Bath, Sagadahoc County17% of 59 wells
- Portland, Cumberland County17% of 60 wells
- Tremont, Hancock County14% of 49 wells
- Rockport, Knox County14% of 44 wells
- Steuben, Washington County13% of 67 wells
- Exeter, Penobscot County13% of 30 wells
- Alton, Penobscot County13% of 92 wells
- Plymouth, Penobscot County13% of 47 wells
- Camden, Knox County13% of 39 wells
- York, York County12% of 97 wells
- Addison, Washington County12% of 49 wells
- Brooklin, Hancock County12% of 50 wells
- Searsport, Waldo County12% of 61 wells
- Gouldsboro, Hancock County11% of 88 wells
- Waterville, Kennebec County11% of 35 wells
- Phippsburg, Sagadahoc County11% of 125 wells
- Brooksville, Hancock County11% of 92 wells
- Gardiner, Kennebec County11% of 65 wells
- Boothbay, Lincoln County11% of 140 wells
- Berwick, York County11% of 56 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.
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. manganese counts and shares are listed on each county and town page with their sources.