Well Water Testing in New Hampshire

There are three routes, and they are good at different things. The mistake is treating them as interchangeable: a screening test is not a lab report, and a lab report is not a treatment plan.

Use the accredited-lab route when the number has to stand up to someone else, a buyer, a lender, or a town. Use the in-home test when the question is "do I have a problem and what does it cost to fix", which is most people most of the time. Nothing stops you from doing both, and on a bedrock well in this state that is a reasonable plan.

NHDES publishes the list, and it is shorter than people fear. Two tests on a yearly clock, everything else on a three to five year clock.

Panel and frequency: NHDES, Suggested Water Quality Testing for Private Wells (DWGB-2-1), listed in the sources below.

PFAS stands for per- and polyfluoroalkyl substances, a group of thousands of human-made chemicals developed in the 1940s to repel water or make a surface slippery. They went into clothing, carpet, furniture, non-stick cookware, food packaging, personal care products, ski waxes and, historically, firefighting foam. They do not break down in the environment, they stay in the body for years, and they are now common drinking water contaminants across the United States.

New Hampshire is not a bystander in this story. The state has documented PFAS impacts including groundwater contamination at the Pease Air Force Base site in Portsmouth, and water, soil and air emissions from industrial facilities in southern New Hampshire. In 2016, NHDES ordered two of Merrimack's six public water wells closed after they tested over the state regulatory limit in force at the time.

The part that matters if your water comes from a well: public systems are tested for you, and private wells are not. New Hampshire's own public fact sheet says homeowners with private wells are solely responsible for testing and treating their water, and that testing is the only way for a private well user to know whether PFAS is there.

One practical note before the numbers: PFAS is not part of the standard NHDES analysis panel described above, so it is a test you ask for by name. A routine homeowner panel that came back clean did not check for it.

The four New Hampshire PFAS groundwater standards

New Hampshire sets ambient groundwater quality standards for four PFAS compounds. These are the numbers in the state's contaminated site rules, and they are strict: the unit is parts per billion, and every one of these is a small fraction of one.

New Hampshire Code of Administrative Rules, Env-Or 600 (Contaminated Site Management), Env-Or 603.03, Table 600-1, ambient groundwater quality standards, each figure stated for the total of all isomers. Read 2026-08-13. The rule states its unit as micrograms per liter, which it notes is the same as parts per billion; the third column is that same figure written out.

Two limits on what those numbers mean, and both matter. They are groundwater standards from the contaminated site rules, and New Hampshire keeps its drinking water limits in a separate chapter that we have not read, so ask your accredited laboratory which standard it reports against. And they apply to contamination that results from human activity. That distinction decides a lot in this state: arsenic and uranium coming out of granite are natural, so nobody is liable for them and the cost of treating them is yours. A PFAS plume from a discharge is a different situation entirely, which is the next section.

If someone else's contamination reaches your well

This is the part almost nobody knows. Under the same rules, a person who is liable for, or has caused or contributed to, contamination above one of those groundwater standards has to provide potable water to any impacted well owner. Not advice, not a referral. Water. Specifically: bottled water straight away as an interim measure, and then a long-term supply that is either a point-of-entry treatment system at each structure served, installed, tested and maintained by them, or a connection to a public water system. The rule says the public water connection is required whenever practicable.

Env-Or 603.04, Safe Alternate Water, effective 12-25-24, read 2026-08-13. This applies where a responsible party's discharge is the cause. It does not reach naturally occurring contamination.

Definition, New Hampshire impacts, the Merrimack well closures and the private-well responsibility: "PFAS in New Hampshire: What You Need to Know", revised June 2023, read 2026-08-13. Health effects are described by that fact sheet and by ATSDR, and are not restated here as our own findings.

A test is only useful if you act on it. If a result comes back above the recommended level, a licensed local contractor can recommend and install treatment sized to your water. New Hampshire's enforceable arsenic standard is 5 parts per billion, half the federal limit, so an arsenic result between 5 and 10 is already worth addressing. The state's groundwater rules carry the same figure and date it: 10 parts per billion through June 30, 2021, and 5 from July 1, 2021 on.

From there, the path depends on your results: a system for arsenic, treatment for uranium or radon, or a whole-house system when several contaminants are present. If you are testing because you are buying or selling a home, see our guide to well water testing before a home sale.

• If your test shows arsenic, see Arsenic in Well Water Treatment.
• If your test shows uranium, see Uranium in Well Water Treatment.
• If your test shows radon, see Radon in Well Water Treatment.
• If your test shows iron or manganese, see Iron and Manganese Treatment.
• If several contaminants show up, see Whole-House Water Treatment.
• To protect drinking water at one tap, see Reverse Osmosis Systems.