Radon in well water in New Hampshire
Who should test well water for radon in NH, NHDES guidance levels, and treatment options.
Radon is common in water from bedrock (drilled) wells in New Hampshire. Dug and point wells tend to have little or none, according to NHDES. Radon in water gets into the air when you shower, wash dishes or do laundry. A common rule of thumb: every 10,000 pCi/L in water adds about 1 pCi/L to indoor air.
The bigger risk is radon in air, so test your air first. NH DHHS also recommends testing private well water.
NHDES guidance levels
There are no federal or state standards for radon in private well water. NHDES recommends:
- 10,000 pCi/L or higher: treat the water, along with mitigating indoor air radon.
- 2,000 to 10,000 pCi/L: water treatment may be advisable if indoor air radon is above 4 pCi/L.
- Below 4,000 pCi/L: retest air and water every 3 to 5 years.
NHDES recommends at least two water tests, a month apart when possible, before deciding on treatment.
How to test
The NH Public Health Laboratories in Concord tests well water for radon; order test containers through the lab. Accredited private labs also test water.
Treatment
Per NH DHHS, water radon is usually removed by an aeration system where the well line enters the home, venting radon outside. Charcoal filters work less well above 2,000 pCi/L, need regular changes, and can build up radioactivity. NH doesn't require water radon installers to be radon-certified, though they may need a plumbing license.
In New Hampshire? Order a free state test kit or see radon by NH county.
More guides
- How to read a radon test result (pCi/L)
- Short-term vs long-term radon tests
- Radon testing when buying or selling a home in NH
- Radon mitigation basics
- When to retest for radon
Sources
- NHDES fact sheet WD-DWGB-3-12, Radon in Your Home
- NH DHHS, Fixing Radon: Mitigation
- NH DHHS, Testing for Radon
- NH DHHS Radon Program data brief, July 2026
Sources checked October 31, 2026. Spot an error? Send a correction.