Iron in well water
The county where Iron is found above the limit most often is Cheshire County, New Hampshire: 24% of 428 private wells tested, according to NH DHHS.
Iron is a nuisance rather than a health hazard: rust stains, metallic taste, and clogged fixtures above 300 ug/L. It often occurs with manganese and can feed iron bacteria that foul plumbing.
- Nuisance level
- 300 ug/L
- New Hampshire level
- 300 ug/L
- CAS number
- 7439-89-6
Where iron 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 | |
|---|---|---|---|---|
| Cheshire County, New Hampshire | 428 | 24% | 69,000 ug/L | |
| Belknap County, New Hampshire | 1,481 | 24% | 66,400 ug/L | |
| Sullivan County, New Hampshire | 610 | 20% | 59,600 ug/L | |
| Grafton County, New Hampshire | 2,109 | 20% | 48,600 ug/L | |
| Merrimack County, New Hampshire | 4,212 | 20% | 74,200 ug/L | |
| Coos County, New Hampshire | 431 | 19% | 22,300 ug/L | |
| Carroll County, New Hampshire | 1,639 | 16% | 13,600 ug/L | |
| Strafford County, New Hampshire | 440 | 15% | 33,200 ug/L | |
| Hillsborough County, New Hampshire | 3,290 | 15% | 87,800 ug/L | |
| Rockingham County, New Hampshire | 2,780 | 13% | 36,900 ug/L |
How to test
Use a state-certified lab and a proper sampling bottle; hardware-store strips cannot measure iron 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 whole-house
- Water softener (low levels)
- Aeration plus filtration