There are several types of radon control systems used in the control of radon to be considered.

First Let's talk about air-borne radon.  For radon in the air the following methods or systems are used:

1) Sub-slab depressurization- when the basement floor is concrete

2) Sub-membrane depressurization- when the basement or crawlspace floor is not concrete

3) Air exchanger - when option numbers 1 & 2 are not feasible

and the next is for radon in water.

4) Water aeration- when you have a higher than desired level of radon in your water

There are systems that 'filter' radon from water.  We do not use, nor do we recommend the use of those system.