Radon retest calendar · EPA timing
How often to test for radon: your retest dates
Enter the date your system started, or the date of your last test. The page works out EPA's dates and saves them to your own calendar. Nothing you type leaves this page.
EPA gives a fixed retest interval only for homes with a system (with a system in place, epa suggests retesting at least every two years.). For a home without one, EPA says to test again at some point, and again on any lower level you start living on; choose your own interval.
EPA's retest timing
- Below 4: retest sometime
- Even with a result under 4 pCi/L, EPA suggests testing again at some point in the future.U.S. Environmental Protection Agency, read October 15, 2026
- Retest a newly used level
- If you start living on a lower level, such as a basement, EPA says to retest on that level.U.S. Environmental Protection Agency, read October 15, 2026
- Post-mitigation test window
- After a system goes in, test within 30 days but not sooner than 24 hours after it starts running.U.S. Environmental Protection Agency, read October 15, 2026
- Independent post-fix tester
- EPA recommends the after-mitigation test be done by an independent, qualified radon tester.U.S. Environmental Protection Agency, read October 15, 2026
- Retest every two years
- With a system in place, EPA suggests retesting at least every two years.U.S. Environmental Protection Agency, read October 15, 2026
The fan and the gauge
- Fan lifespan
- Radon fans may last five years or more and may then need repair or replacement.U.S. Environmental Protection Agency, read October 15, 2026
- Warning device required
- An active system must have a warning device that shows if it stops working properly.U.S. Environmental Protection Agency, read October 15, 2026
- Fan replacement cost
- An EPA FAQ page puts a fan replacement at around $200 to $350, parts and labor included.U.S. Environmental Protection Agency, read October 15, 2026
State rules on the test after a system goes in
- Post-mitigation test window
- The follow-up test may start no sooner than 24 hours and no later than 30 days after the system is finished and switched on.PA Environmental Quality Board, 2018 final rule text (posted by DEP), read October 15, 2026
- Retest advice
- The information package must recommend retesting the home at least every 2 years.PA Environmental Quality Board, 2018 final rule text (posted by DEP), read October 15, 2026
- Mitigators cannot test own work
- A mitigator who also holds a measurement license may not do the before or after tests at a house where they installed the system, unless another independent person has measured.Illinois General Assembly, Joint Committee on Administrative Rules (Illinois Administrative Code), read October 15, 2026