Manganese in well water
The county where Manganese is found above the limit most often is Sagadahoc County, Maine: 9% of 1,008 private wells tested, according to Maine Tracking Network private well summaries.
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.
- Health guideline
- 300 ug/L
- Nuisance level
- 50 ug/L
- New Hampshire level
- 300 ug/L
- CAS number
- 7439-96-5
Where manganese 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 | |
|---|---|---|---|---|
| Sagadahoc County, Maine | 1,008 | 9% | ||
| Knox County, Maine | 633 | 8% | ||
| Strafford County, New Hampshire | 442 | 8% | 6,400 ug/L | |
| Lincoln County, Maine | 1,691 | 7% | ||
| Coos County, New Hampshire | 429 | 7% | 12,400 ug/L | |
| Sullivan County, New Hampshire | 608 | 7% | 20,300 ug/L | |
| Merrimack County, New Hampshire | 4,208 | 7% | 43,300 ug/L | |
| Rockingham County, New Hampshire | 2,784 | 7% | 24,700 ug/L | |
| Hillsborough County, New Hampshire | 3,290 | 7% | 4,200 ug/L | |
| Hancock County, Maine | 2,494 | 6% | ||
| Belknap County, New Hampshire | 1,470 | 6% | 6,000 ug/L | |
| Washington County, Maine | 1,160 | 6% | ||
| Cheshire County, New Hampshire | 451 | 5% | 2,400 ug/L | |
| Piscataquis County, Maine | 307 | 5% | ||
| Grafton County, New Hampshire | 2,113 | 5% | 19,100 ug/L |
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 |
|---|---|---|---|---|
| Rockingham County, New Hampshire | 385 | 86% | no limit | 90 ug/L |
| Strafford County, New Hampshire | 95 | 83% | no limit | 40 ug/L |
| Cheshire County, New Hampshire | 68 | 81% | no limit | 54.5 ug/L |
| Hillsborough County, New Hampshire | 432 | 81% | no limit | 0 ug/L |
| Sullivan County, New Hampshire | 56 | 71% | no limit | 20.1 ug/L |
| Grafton County, New Hampshire | 244 | 71% | no limit | 30 ug/L |
| Merrimack County, New Hampshire | 542 | 70% | no limit | 40 ug/L |
| Carroll County, New Hampshire | 270 | 69% | no limit | 20 ug/L |
| Belknap County, New Hampshire | 171 | 64% | no limit | 30 ug/L |
| Coos County, New Hampshire | 170 | 62% | no limit | 22.5 ug/L |
How to test
Use a state-certified lab and a proper sampling bottle; hardware-store strips cannot measure manganese at the levels that matter. Collect from the kitchen tap before any treatment, and again after treatment if you install it.
How to treat
- Oxidizing filter (greensand, birm) whole-house
- Water softener (low levels)
- Point-of-use reverse osmosis