Arsenic in New Hampshire well water
In New Hampshire, 25% of 18,685 private wells tested between 2006 and 2020 had arsenic above the New Hampshire guidance level (5 ug/L), according to NH DHHS.
Arsenic occurs naturally in New England bedrock and dissolves into well water. Long-term exposure raises the risk of bladder, lung and skin cancers, and is linked to heart disease and lower IQ in children. It has no taste or smell, so testing is the only way to know.
Check your arsenic 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 arsenic
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 arsenic
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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 arsenic
Under-sink reverse osmosis system
under-sink or countertop, about $300
Look for NSF/ANSI 58 certification listing the contaminant you need removed.
For arsenic
Whole-house arsenic and uranium filter
whole-house, at the point of entry, about $2,500
Adsorptive iron-based media; sized to your well yield.
For arsenic
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 arsenic in New Hampshire: certified labs, state programs and prices.
By county, from homeowner tests
Share of private wells above the state guidance level (5 ug/L) in tests homeowners sent to the state lab, 2006 to 2020.
| County | Above state level | Wells tested | Highest |
|---|---|---|---|
| Strafford | 530 | 183 ug/L | |
| Rockingham | 2,990 | 766 ug/L | |
| Merrimack | 4,603 | 1,040 ug/L | |
| Carroll | 1,741 | 489 ug/L | |
| Hillsborough | 3,558 | 523 ug/L | |
| Belknap | 1,532 | 753 ug/L | |
| Sullivan | 627 | 304 ug/L | |
| Cheshire | 492 | 34.1 ug/L | |
| Grafton | 2,176 | 313 ug/L | |
| Coos | 436 | 29.4 ug/L |
Towns with the highest share above the state level
- Hampton Falls, Rockingham County83% of 36 wells
- Kensington, Rockingham County79% of 34 wells
- Lee, Strafford County66% of 35 wells
- Bow, Merrimack County65% of 689 wells
- Goffstown, Hillsborough County62% of 135 wells
- Pembroke, Merrimack County61% of 113 wells
- Rollinsford, Strafford County60% of 37 wells
- Epping, Rockingham County59% of 44 wells
- South Hampton, Rockingham County58% of 50 wells
- Hancock, Hillsborough County56% of 96 wells
- Dunbarton, Merrimack County56% of 142 wells
- Plaistow, Rockingham County55% of 264 wells
- East Kingston, Rockingham County55% of 33 wells
- Hudson, Hillsborough County53% of 156 wells
- Stratham, Rockingham County50% of 113 wells
- Chichester, Merrimack County48% of 188 wells
- Pelham, Hillsborough County48% of 139 wells
- Francestown, Hillsborough County48% of 46 wells
- Concord, Merrimack County46% of 391 wells
- Durham, Strafford County45% of 73 wells
- Chester, Rockingham County44% of 91 wells
- Brentwood, Rockingham County43% of 51 wells
- Epsom, Merrimack County43% of 146 wells
- Strafford, Strafford County42% of 97 wells
- Madbury, Strafford County42% of 45 wells
By county, from individual samples
Public monitoring samples against the EPA limit (10 ug/L); counties with at least 30 samples.
| County | Above EPA limit | Samples | Detected | Median | Highest |
|---|---|---|---|---|---|
| Rockingham | 322 | 75% | 4.2 | 150 ug/L | |
| Merrimack | 206 | 61% | 0.65 | 300 ug/L | |
| Hillsborough | 225 | 58% | 1 | 140 ug/L | |
| Strafford | 71 | 56% | 1 | 56 ug/L | |
| Sullivan | 32 | 47% | 0 | 29 ug/L | |
| Grafton | 67 | 33% | 0 | 30 ug/L | |
| Carroll | 79 | 20% | 0 | 160 ug/L | |
| Coos | 43 | 21% | 0 | 6 ug/L | |
| Belknap | 32 | 9% | 0 | 5 ug/L |
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.
- Individual samples from the USGS Water Quality Portal and state monitoring, summarized per geography. arsenic counts and shares are listed on each county and town page with their sources.
Analysis: Arsenic in private wells, state by state, from the same public records.