WELL-TO-HOME LOSS OF WATERBORNE RADON

Based on a study of @1000 homes in two northern Virginia counties, we find that although potable water from the local reservoir is almost devoid of radioactivity, most water wells require some form of remediation to provide water with less that 300 pCi/L, the USEPA's recommended Maximum Contamination Level for radon in water. In Fairfax County, a set of @250 wells at private homes showed that the average was @2000 pCi/L. In Prince William County, immediately south of Fairfax County, a study of 10 systems, each with several large diameter and large productivity wells that serve small communities, showed that wells drilled into granite carried an average of 3150 pCi/L, schist carried an average of 1500 pCi/L, red sandstone carried an average of 1800 pCi/L, and white quartzite carried an average of 1300 pCi/L. Measurements made at water well storage tanks, when compared to measurements made at homes, showed that the waterborne radon fell by about 20-40% in transport. However, even after the radon decrease in transport, most potable water from wells require at-home remediation (usually activated granular charcoal) to comply with the USEPA's MCL.