Uranium and Radon in New Hampshire Well Water

New Hampshire's bedrock is largely granite and metamorphic rock, which has a high potential to contain uranium. As uranium decays, it produces radon, a radioactive gas. USGS mapping shows that much of central and eastern New Hampshire has an elevated probability of radon and uranium in groundwater, and bedrock wells tend to carry higher levels of these natural contaminants than shallow wells.

Uranium in drinking water is mainly a concern for the kidneys. The federal ATSDR describes soluble uranium as a kidney toxin at elevated levels, and the EPA sets a federal limit of 30 micrograms per liter for uranium in drinking water. As with arsenic, this is about long-term exposure, and the practical response is to test and, if needed, treat.

Radon in water and radon in air are related but distinct. NHDES explains that the larger health risk comes from radon in indoor air, where it is the well-known lung-cancer risk, and that radon dissolved in well water escapes into the air when you shower, do laundry, or run the tap, adding to that indoor air level.

NHDES recommends treating well water when radon is at or above 10,000 picocuries per liter, and treatment may be advisable between 2,000 and 10,000 picocuries per liter when indoor air radon is also elevated. Because the two are connected, testing both the water and the indoor air gives the complete picture.

Both are found through a radiological test, which a standard NHDES testing schedule suggests every three to five years. A single laboratory analysis can report arsenic, uranium, and radon together, which is why a contractor often recommends testing for all of the bedrock contaminants at once.

The treatment methods differ because the contaminants behave differently. Uranium, which is charged in water, is removed by anion exchange or by reverse osmosis at the tap. Radon, a dissolved gas, is removed by whole-house aeration, which NHDES considers the preferred method, or by granular activated carbon at lower levels.

A licensed local contractor matches the method to your levels and household, and because uranium and radon so often come with arsenic, a single system can sometimes address more than one.

For uranium, the federal limit is 30 micrograms per liter, and a result is straightforward to read against it. For radon in water, NHDES points to 10,000 picocuries per liter as the level at which it recommends treating the water, with the 2,000 to 10,000 range worth treating when indoor air radon is also elevated.

As with arsenic, these are long-term exposure benchmarks rather than emergency thresholds. A number above them is a reason to plan treatment, not to panic, and both contaminants are very treatable once measured.

Uranium is removed by anion exchange, which captures it on a resin bed, or by reverse osmosis at the tap. Because the captured uranium concentrates radioactivity over time, a licensed contractor manages replacement and disposal of the media correctly rather than leaving it to build up in the home.

Radon is a dissolved gas, so it is handled differently. Whole-house aeration, which NHDES considers the preferred method, strips radon from the water and vents it outside before it reaches your taps. Granular activated carbon can work at lower levels, but it concentrates radioactivity and needs careful placement and periodic media changes.

Because uranium and radon come from the same bedrock as arsenic, it is a mistake to assume an arsenic system covers them. The treatment methods are different, and a home that handled its arsenic may still have untreated uranium or radon. A radiological test settles the question and lets a contractor design around the full set of contaminants.