Private Well Water Testing in New Hampshire
County-by-county USGS area-risk estimates for private wells across New Hampshire — arsenic exceedance probability and private-well population — plus how to test your own well at a New Hampshire-certified laboratory.
New Hampshire private-well risk summary
Counties covered
10
New Hampshire counties with modeled risk data.
People on private wells
area estimate396,619
estimated across covered New Hampshire counties.
Average arsenic risk
area estimate10%
average modeled chance a well exceeds 10 µg/L arsenic across covered counties.
New Hampshire counties
- Rockingham County16% arsenic exceedance (area estimate)97,114 people on private wells
- Hillsborough County18% arsenic exceedance (area estimate)76,831 people on private wells
- Merrimack County22% arsenic exceedance (area estimate)51,027 people on private wells
- Grafton County4% arsenic exceedance (area estimate)34,331 people on private wells
- Cheshire County9% arsenic exceedance (area estimate)31,625 people on private wells
- Strafford County14% arsenic exceedance (area estimate)28,735 people on private wells
- Belknap County6% arsenic exceedance (area estimate)26,802 people on private wells
- Carroll County4% arsenic exceedance (area estimate)25,758 people on private wells
- Sullivan County8% arsenic exceedance (area estimate)16,887 people on private wells
- Coos County3% arsenic exceedance (area estimate)7,509 people on private wells
Find a New Hampshire-certified testing lab
Get your well tested at a New Hampshire-certified laboratory. We list certification programs by state.
Already tested your well? Get a free plain-English reading
Upload your well water lab report (PDF or a photo) and our team will email you a full, plain-English reading of every result — free. Educational only, never medical advice.
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Upload my well testThese figures are USGS area estimates: statistical groundwater models describing how likely elevated contaminant levels are across a county. They are not designed to predict the concentration in any single well. Only testing your own well reveals its water quality.
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