Nitrite in New Hampshire well water
In New Hampshire, <1% of 18,077 private wells tested between 2006 and 2020 had nitrite above the New Hampshire guidance level (1 mg/L), according to NH DHHS.
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.
Check your nitrite number
Type the value from your lab report. It is compared to the New Hampshire guidance level and the EPA limit, the same way the full interpretation does it.
Test your New Hampshire well for nitrite
Certified lab analysis of your own tap water, bottles and prepaid return shipping included. The Essential well panel covers arsenic, uranium, nitrate, lead, copper, manganese, iron, sodium and bacteria; radon and PFAS are add-ons.
Order the Tap Score well water test kit, from $209Already tested? Upload the report
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Systems that remove nitrite
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Some links below are affiliate links. If you buy through one, the merchant pays us a commission at no extra cost to you. It does not change which products we list or what the data says.
For nitrite
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For nitrite
Aquasana SmartFlow reverse osmosis
under-sink or countertop, about $225
Certified to NSF/ANSI 58 and 53 to reduce arsenic (96%, pentavalent), fluoride (90%), lead (99%), nitrate, nitrite and PFOA/PFOS at the kitchen tap, with a remineralizer.
Rather have it installed and sized for your well? Book a free in-home water test with a licensed local company.
Where to get a well tested for nitrite in New Hampshire: certified labs, state programs and prices.
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, 2006 to 2020.
| County | Above state level | Wells tested | Highest |
|---|---|---|---|
| Sullivan | 733 | 1.8 mg/L | |
| Merrimack | 4,873 | 0.5 mg/L | |
| Grafton | 2,686 | 0.4 mg/L | |
| Rockingham | 2,332 | 0.5 mg/L | |
| Hillsborough | 2,118 | 0.8 mg/L | |
| Carroll | 1,819 | 0.2 mg/L | |
| Belknap | 1,734 | 0.4 mg/L | |
| Cheshire | 637 | 0.1 mg/L | |
| Coos | 603 | 0.4 mg/L | |
| Strafford | 542 | 0.1 mg/L |
Towns with the highest share above the state level
- Washington, Sullivan County<1% of 111 wells
- Bow, Merrimack County0% of 594 wells
- Tuftonboro, Carroll County0% of 561 wells
- Hopkinton, Merrimack County0% of 393 wells
- Concord, Merrimack County0% of 388 wells
- Moultonborough, Carroll County0% of 332 wells
- Loudon, Merrimack County0% of 326 wells
- Holderness, Grafton County0% of 273 wells
- Weare, Hillsborough County0% of 273 wells
- Windham, Rockingham County0% of 268 wells
- Meredith, Belknap County0% of 267 wells
- Newbury, Merrimack County0% of 263 wells
- Alton, Belknap County0% of 238 wells
- Hillsborough, Hillsborough County0% of 222 wells
- Gilmanton, Belknap County0% of 219 wells
- New London, Merrimack County0% of 215 wells
- Sandwich, Carroll County0% of 211 wells
- Henniker, Merrimack County0% of 208 wells
- Canterbury, Merrimack County0% of 198 wells
- Sunapee, Sullivan County0% of 195 wells
- Chichester, Merrimack County0% of 195 wells
- Plaistow, Rockingham County0% of 195 wells
- Barnstead, Belknap County0% of 190 wells
- Andover, Merrimack County0% of 189 wells
- Campton, Grafton County0% of 186 wells
Sources
- NH DHHS WISDOM private well summaries: Town summaries of private well tests run by the New Hampshire Public Health Laboratories, published by NH DHHS through the WISDOM environmental public health tracking portal. Exceedance shares use New Hampshire guidance levels, which are stricter than EPA for arsenic (5 ug/L), manganese (0.3 mg/L), radon (2,000 pCi/L) and sodium (20 mg/L). Statistics for small counts are suppressed (*). Retrieved September 3, 2026.