How to choose a radon testing or mitigation company

1. Start with the job type

Do you need a test, a mitigation system, or both? And is the concern radon in air, radon in water, or both? A testing-only inspection company can test but cannot install a system. A water company may treat radon in water only. A mitigation specialist installs systems. Start with the type that matches the job, and confirm the scope in the company's own words before you book.

2. Verify the credential yourself

Ask for the license or certification number and check it yourself. In Connecticut there is no state radon license as such: radon professionals typically hold national certification (NRPP or NRSB), and companies that contract mitigation work with consumers register as Home Improvement Contractors with the Connecticut Department of Consumer Protection; radon-in-water mitigation may also involve a plumbing license. Only 4 of the 23 companies in this guide publish a number on their own website, so for every other company here the credential is claim-only or not published until you verify it yourself. A claim on a website is not a verified credential, and a review-site badge is not a credential.

3. Separate air from water

Radon in air and radon in water are handled with different systems. Ask which one the company tests, which one it mitigates, and what system it proposes for each. Do not assume a company that treats well water also installs air mitigation systems, or the reverse.

4. Ask what happens after a high result

Ask what the company does if a test result calls for mitigation: does it install the system itself, or does it refer you to a mitigator? Ask whether retesting after mitigation is included and what happens if the follow-up result calls for adjustments.

5. Ask about crew, timeline and equipment left in place

Ask who does the work — the company's own crew or subcontractors — how long testing and installation take, and what equipment stays in the home (fan, piping, monitor or alarm, if any). Ask how the system is maintained and what fan replacement or servicing costs.

6. Service-area companies

A service-area company serves Fairfield County but either publishes an office outside the county or publishes no street address on its own site. That is not a red flag on its own, but confirm response time, who comes to your home, and whether the crew is in-house or subcontracted before you book.

7. Get it in writing before work starts

Scope (air, water, rooms, retesting), system type, installer, timeline, equipment left in place and total price should all be in one written quote. Verbal promises about price, timeline or results are hard to enforce later.