 If radon comes out of the ground, especially in well water, it can be introduced into the well water and allowed to come up because it's pumped up out of the ground into your house as the water comes out of the faucet. Does it need to be treated if it's high back row levels? The answer is absolutely yes. How do you know you need to have it tested by a professional? We're learning more and more about radon only because we're talking about it. This is something that should be a big subject considering it is the single most cause for lung cancer besides smoking cigarettes.