Niche tool · not a test result
Washington County radon risk explainer
Pick the county, the foundation, and how you get water. We will tell you what usually matters in this valley. We will not print a pCi/L number for your address. That takes a device in the room.
Context only · not a radon reading
Washington County is EPA Zone 1
The EPA map puts Washington County in Zone 1, the highest predicted indoor-radon band (average screening above 4 pCi/L). That is a planning map from geology and older measurements, not a reading for your street. Carter and Unicoi next door are Zone 2. The line does not stop radon at the county sign. Test the house you actually sleep in.
Crawl space is the common Johnson City story
Most of the housing stock we see is a crawl over soil. Radon moves through that dirt, then through the floor and the return leaks. Mitigation is usually a sealed polyethylene membrane plus a fan that pulls from under the plastic (sub-membrane depressurization), not a box fan in a vent. Mid-century ranches around here usually sit on a crawl with a dirt floor and a few foundation vents that do not count as a mitigation system.
City water: the job is indoor air
If you are on Johnson City, Jonesborough, Kingsport, or Bristol utility water, the radon conversation is the air in the house. Utility water is treated and is not the usual indoor-radon driver here. Test the lowest lived-in level. Leave the geology map for context.
Living there: a careful kit or a professional test
If you just want a number, Tennessee's radon program will mail a free short-term kit. Follow the 3 to 5 day window and mail it back immediately. If you want us to place a monitor and write it up, request a quote. Either way, this tool will not invent a pCi/L reading for your address.
- Zone 1 here. Useful for why we take the county seriously. Useless as a substitute for a test.
- Expect a crawl-space membrane system if you mitigate, not a hardware-store fan in a vent.
- Utility water: skip the water scare. Book an air test in the lowest lived-in room.
- Occupied home: TDEC kit for a first look, or hire us to run a professional test.
Request a quote
Tell us the town and the foundation. We will not guess a number from this form.
Want an actual measurement?
Request a quote. The explainer is context. The test is the number.