Naturally occurring radionuclides in community water supplies of New York State

During a 2-y study, drinking-water samples were analyzed for gross-alpha and gross-beta activity in 1,869 community water supplies in New York State. Among these, 87 and 14 samples were further analyzed for radium and uranium activity, respectively. The results showed that concentrations in drinking water samples met regulatory limits for gross-alpha, gross-beta, and combined radium in over 99% of the community water supplies tested. Gross-alpha activity in 97% of the supplies was below half of the maximum contaminant level. In the water samples that exceeded the maximum contaminant level, a significant part of the gross-alpha activity was contributed by dissolved uranium. In the 14 supplies that contained >556 mBq L-1 (15 pCi L-1) of gross-alpha activity, the mean uranium concentrations were 548 mBq L-1 and ranged from 36 to 2,135 mBq L-1. In the 87 supplies that contained >185 mBq L-1 of gross-alpha activity, the mean Ra-226 and Ra-228 concentrations were each 52 mBq L-1. Based on the mean concentrations in the measured water supplies, the radioactive dose due to ingestion of Ra-226, Ra-228, and uranium is about 27 muSv y(-1), respectively, with Ra-228 alone producing half of the dose.