RADON VARIATIONS IN POTABLE WELL WATER IN VIRGINIA AND MARYLAND

In northern Virginia and southern Maryland, municipal water supplies obtained from reservoirs provide radon-free potable water. However, about 10% of the population consumes well water, and radon from some wells exceeds 10,000 pCi/L. The average well water is about 2000 pCi/L, which greatly exceeds US-EPA's maximum contamination level of 300 pCi/L. The most radioactive water comes from granite and schist. In well-verses-home studies, about 30% of the radon was lost by radioactive decay between the well and the home. Radon removal experiments showed that about 60-70% of the radon can be removed at the wellsite storage tank by water agitation, using an internal splash box or by using bubble aeration. Using wellsite tanks of activated charcoal removed about 90% of the radon.