Well Water Notebook
Information only, not medical advice. We never say whether your water is safe to drink. Ask a state-certified lab or your local health department. Disclaimer

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Well water testing in Hillsborough County, New Hampshire

How common arsenic is in Hillsborough County wells, what New Hampshire recommends you test for and how often, and where to get a sample analyzed, with a source for every fact.

This page can't tell you whether your water is safe to drink. Only a test of your well can do that. For help with results, contact NHDES (below) or an accredited laboratory.

How many people here use a private well

USGS estimates that about 116,000 people in Hillsborough County supplied their own household water in 2015, about 29% of the county's population.1 Statewide, NHDES says nearly half of New Hampshire residents get their water from a private well.2

What tests in Hillsborough County have found

Arsenic

NHDES estimates that 25–30% of private residential wells statewide have arsenic at 5 ppb or higher. New Hampshire's 5 ppb arsenic standard (in effect since July 1, 2021) applies to public water systems, not private wells.6

Radon and other contaminants

Statewide, in private well samples in the combined NHDES/NH Public Health Laboratories data set from 2006 to August 2020, 30% were over the 2,000 pCi/L radon testing advisory level, 17% were over 0.3 mg/L iron, 5% were over 0.30 mg/L manganese, and 4% were over the uranium limit (labeled "30 mg/L" in the NHDES table; the EPA standard is 30 µg/L).38 We haven't verified a county-level breakdown of these results for Hillsborough County, so we don't publish one. For town-level numbers, see the NH DHHS Private Well Water Quality Dashboard.

PFAS

NHDES has been sampling private wells for PFAS since 2016. On the NH PFAS Response website, a "Sampling Dashboard" shows existing results, and a "Private Well Testing Request Form" lets you ask NHDES to sample your well.7

Does New Hampshire require testing?

NHDES says there is no statewide testing or treatment requirement for private wells, but some towns require it.3 As of NHDES's September 2021 presentation, Pelham was among the towns requiring well water testing to get a certificate of occupancy, and Goffstown required compliance with standards for water to be considered "potable."3 Check with your town for its current rules.

What to test for and how often

NHDES's April 2026 guidance recommends testing for:7

When to test:7

Who When
Private well users Bacteria, nitrate and nitrite every year. Everything else on the list every 3–5 years.
Home buyers Before buying a home with a private well, if the seller hasn't provided a recent test.
After installing treatment Test the treated water to confirm it's working, then every 3–5 years.

NHDES notes that PFAS sampling can be costly. If a first PFAS test finds none and your budget doesn't allow retesting every 3–5 years, NHDES says it's acceptable to wait longer, especially if nearby land uses don't change.7

Where to get tested and treatment options

Accredited labs. NHDES lists laboratories accredited by the NH Environmental Laboratory Accreditation Program (NHELAP) that serve private well users. Those with locations in or near Hillsborough County include:7

Lab Location Phone
Nelson Analytical Manchester (603) 622-0200
Granite State Analytical Services Derry (drop-off locations include Amherst) (603) 432-3044
Nelson Analytical (Keene) North Swanzey (603) 357-2577
Eurofins Environment Testing Eastern Analytical Concord (603) 228-0525
NH DHHS Public Health Laboratories (state lab) Concord (603) 271-3445

NHDES's list was last updated 9/20/2024, so confirm with the NHELAP Accredited Laboratory Search and ask each lab whether it's accredited for every test you need.7

If a result is high. Enter your results into NHDES's Be Well Informed tool, which gives information on health effects and the type of treatment that addresses each result.2 For arsenic, radon and uranium, our guides walk through the treatment types state agencies describe:

Who to contact

Contact Details
NHDES private well testing WellTest@des.nh.gov3
NHDES (main office) 29 Hazen Drive, Concord, NH 03302-0095 · (603) 271-35032
Lab accreditation questions (NHELAP) (603) 271-2998 / (603) 271-5314 · nhelap@des.nh.gov7

  1. Dieter, C.A., and others, 2018, Estimated Use of Water in the United States County-Level Data for 2015 (ver. 2.0), U.S. Geological Survey data release (domestic self-supplied population). https://doi.org/10.5066/F7TB15V5 ↩

  2. NHDES, "Private Wells." https://www.des.nh.gov/water/drinking-water/private-wells ↩↩↩

  3. Kernen, B., NHDES, "Private Wells in Portsmouth" (presentation, September 1, 2021; data: EPHT combined NHDES/NH Public Health Laboratories data set, 2006–August 2020), hosted by the City of Portsmouth. https://www.portsmouthnh.gov/sites/default/files/2021-09/Portsmouth%20SWAG%20Sep%201%202021%20DES.pdf ↩↩↩↩

  4. U.S. Geological Survey, "Arsenic Concentrations in Private Bedrock Wells in Southeastern New Hampshire," Fact Sheet 051-03 (2003), table 1. https://pubs.usgs.gov/fs/fs-051-03/ ↩

  5. Ayotte, J.D., Medalie, L., and Qi, S.L., 2017, Estimated county level domestic well population with arsenic greater than 10 micrograms per liter based on probability estimates for the conterminous U.S., U.S. Geological Survey data release. https://doi.org/10.5066/F7CN724V ↩

  6. NHDES, "More Protective Arsenic Standard Will Reduce Risk for Many" (March 8, 2021). https://www.des.nh.gov/news-and-media/blog/more-protective-arsenic-standard-will-reduce-risk-many ↩

  7. NHDES, "Water Testing Guidance for Private Well Users" (April 2026; lab list updated 9/20/2024). https://www.des.nh.gov/sites/g/files/ehbemt341/files/documents/labs-private-wells.pdf ↩↩↩↩↩↩↩

  8. U.S. EPA, "Radionuclides Rule." https://www.epa.gov/dwreginfo/radionuclides-rule ↩