Radon mitigation in Nashua, Manchester & southern NH

If your home tested high for radon, a properly designed mitigation system can usually bring it down. Here’s what to expect, what to ask, and how to get a quote from a local pro.

When should you fix your home?

The EPA recommends fixing your home if your radon level is 4 pCi/L or higher. Because levels below 4 still carry some risk, the EPA also suggests considering a fix between 2 and 4 pCi/L. (EPA Citizen’s Guide) NH DHHS notes the EPA goal when you take action is to bring radon below 2.0 pCi/L. (NH DHHS)

If you only have one short-term result, the EPA’s guide explains when to follow up with a second test before deciding. See our testing guide.

How a typical system works

Most New England homes with basements or slabs are fixed with sub-slab depressurization: a pipe is placed through the slab, and a fan continuously pulls soil gas from under the foundation and vents it above the roofline, before it can seep inside. Homes with crawl spaces often use a sealed plastic membrane with suction underneath (sub-membrane depressurization). Sealing cracks helps but is not usually enough by itself. (EPA)

Radon systems need little maintenance. NH DHHS notes the fan is the main part that can fail, and radon fans typically last 10–15 years. (NH DHHS)

What does it cost?

It depends on how your house was built and how high the level is. The EPA says most homes can be fixed for about the same cost as other common home repairs. (EPA) The only reliable number is a written quote for your home — ask for one that spells out the fan, pipe route, and post-mitigation test.

Questions to ask any mitigation contractor

• Are you nationally certified? NHDES states that since January 1, 2015, radon-in-air mitigation designers and installers in New Hampshire must be nationally certified. Check the person’s name on the NRPP directory.
• Where will the pipe and fan go? Inside (garage/attic) vs. outside routes affect looks, noise and price.
• Is a post-mitigation test included? You want proof the system worked. The EPA recommends testing after installation and periodically after that. (EPA)
• What’s the warranty on the fan and on the radon reduction itself?
• Is my well water a factor? If you have a private well, ask whether water should be tested too (see below).

Radon in well water

Many homes around Nashua and Manchester — especially in towns like Amherst and Milford — rely on private bedrock wells. Radon dissolved in water is released into the air when you shower, run faucets, or do laundry. NH DHHS estimates that for every 10,000 pCi/L in water, roughly 1 pCi/L can reach indoor air. (NH DHHS)

NHDES recommends water treatment for wells at or above 10,000 pCi/L (alongside air mitigation), and says treatment may be advisable between 2,000 and 10,000 pCi/L if indoor air is 4 pCi/L or higher. Whole-house aeration is the preferred technology. (NHDES, NHDES)

Radon-in-water treatment does not require radon certification in NH, though installers may need a plumbing license. (NH DHHS)

Buying or selling?

Radon often comes up in the inspection period. A mitigation contractor who can schedule quickly and provide a written quote helps both sides negotiate. NH DHHS recommends a nationally certified measurement professional when a sale is involved. (NH DHHS)