Arsenic is widespread in Rockingham County wells.
1 widespread, 2 worth checking, 3 rare out of 6 health checks.
From 32 wells tested in Rockingham County since 2000; your own well needs its own test. How to read this
Not charted, because fewer than 10 wells were tested: radon (4).
Rare: under 5%Worth checking: 5 to 15%Widespread: 15%+
Lab results: Water Quality Portal (USGS and EPA)
Who drinks from a well here
5 in 10 people 165,527 people
Nobody else tests these wells. Only you do.
People on wells: EPA researchers' 2020 estimate
Radon risk (a gas from rock)
Possible here. A home air test is inexpensive.
Radon zones: EPA map
Here's how Rockingham County compares with New Hampshire and the counties around it.
Each result puts Rockingham County next to the 5 counties that border it, on the chart's 0 to 50% scale.
This one is widespread in Rockingham County wells.
Arsenic9 of 31 wells over
* Likely overstated, so we don't rank it.
Too few tested to show: Essex, MA, Merrimack, Strafford.
These 2 are worth checking in Rockingham County.
Manganese2 of 31 wells over
Too few tested to show: Essex, MA, Merrimack, Strafford.
Uranium2 of 31 wells over
Too few tested to show: Essex, MA, Merrimack, Strafford.
These 3 are rare in Rockingham County.
Fluoride0 of 10 wells over
Too few tested to show: Essex, MA, Merrimack, Strafford.
Nitrate0 of 10 wells over
Too few tested to show: Essex, MA, Merrimack, Strafford.
Lead0 of 19 wells over
Too few tested to show: Essex, MA, Merrimack, Strafford.
Too few Rockingham County wells were tested for this one.
Radon in water4 wells tested
Coliform bacteria turned up in 2 of 3 tested Rockingham County wells, so test for it every year.
Coliform bacteria2 of 3 wells had it
E. coli1 of 4 wells had it
E. coli means human or animal waste is getting in, so if a test of your Rockingham County well finds it, boil drinking water until the well is fixed.
Iron reached staining levels in 9 of 31 tested wells, and it isn't a health risk.
Iron stains9 of 31 wells had it
Too few tested to show: Essex, MA, Merrimack, Strafford.
Rockingham County has 32 tested wells, and the busiest decade for testing was the 2010s.
None of the 32 wells has a test from 2020 or later, so a fresh test of your own well tells you more than any of these.
Most Rockingham County wells in these records were tested for research or because someone suspected a problem, which can push the shares above what a typical home well would show (how we read the numbers).
One mail-in lab test covers the 5 things to check in Rockingham County.
- Bacteria
- Nitrate
- Arsenic
- Uranium
- Manganese
What New Hampshire offers well owners
- Free testingWe didn't find a free program for all of New Hampshire. New Hampshire's private well page
- Certified labsNew Hampshire's list of certified labs
- Well recordsNew Hampshire's well record search
Here's what we know about radon and PFAS in Rockingham County.
Rockingham County is in the EPA's middle radon zone. An indoor air test is cheap and tells you whether to look at your water. Radon guide
Between 2023 and 2025 the EPA had 12 town water systems in Rockingham County test for PFAS. 9 of them had at least one test above 4 ng/L, the new EPA limit for PFOA and PFOS. The highest single result was 8.5 ng/L of PFOA. Only 2 wells in Rockingham County have public PFAS results, so the town systems are the best clue to what's in the groundwater nearby. PFAS guide
Radon zones: EPA Map of Radon Zones. PFAS: EPA tests of town water systems, 2023 to 2025
Questions people ask about well water in Rockingham County
Is well water in Rockingham County safe to drink?
9 of 31 wells tested in Rockingham County had arsenic over the limit, about 3 in 10. Across New Hampshire it's about 2 in 10. So test your own well for arsenic before you count on it.
Where can I get my well tested in Rockingham County?
Use a lab New Hampshire has certified for drinking water. New Hampshire's list is linked above, in the box about testing. Ask for bacteria, nitrate, arsenic, uranium and manganese, the tests that matter most in Rockingham County.
How does Rockingham County compare with the counties around it?
For arsenic, the share of tested wells over the limit: 1 of the 2 neighboring counties with data had a higher share than Rockingham County, at 29%. York, ME had the most, at 62%. Groundwater doesn't stop at county lines, so York, ME's 62% is worth knowing about if you live near it.
How often should I test my well in Rockingham County?
In Rockingham County, 2 of 3 tested wells had coliform bacteria, so the CDC's advice matters here: test for bacteria and nitrate every year, and right away after a flood, a repair, or any change in taste or smell.
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Where the Rockingham County numbers come from
- People on wells: 165,527 in Rockingham County, from EPA estimates built on the 2020 Census (Murray et al.).
- Lab tests: 562 well water samples from 32 wells in the Water Quality Portal, run by the USGS and EPA, 2000 to 2019.
- Neighboring counties: the 5 counties that share a border with Rockingham County, from the Census Bureau's county adjacency file.
- PFAS: EPA tests of 12 town water systems in Rockingham County under the Fifth Unregulated Contaminant Monitoring Rule, 2023 to 2025.
- Radon: Rockingham County is zone 2 on the EPA Map of Radon Zones.
- State programs and links: Department of Environmental Services, checked November 1, 2026.