Simple aeration removes up to 99% of radon from water. Radon is rarely a problem in public systems because the water is aerated during water treatment. Unfortunately, this does not occur in water being drawn from a private well. Aeration treatment equipment aerates the water, then vents the gas to the outside. This treatment option requires that the gas be vented above the roof line, otherwise the gas may enter the home.
Another option is granular activated carbon filtration. In this type of treatment, the water is filtered through carbon which adsorbs the radon. This type of filter requires relatively large amounts of carbon and a long contact time to be efficient. The carbon from a radon filtration system may have to be handled specially for disposal since the potential build up of radioactivity can make it hazardous.