Which part of the home typically displays the highest radon levels? There are usually higher concentrations of radon in the lower floors of the home, including basements and cellars. By ProMatcher Staff Updated: 09/28/2017 Get Free Quotes Today! Get Free Quotes Today! Find Local Pros Free Radon Gas Testing Cost Estimates Related Questions Should well water be tested for radon?Top answer: Yes How often should well water be tested for radon? How do I test for radon gas? How often should I test my home for radon?Top answer: Every other year What is Radon?