AWWA JAW17549

The naturally occurring concentrations of radium (Ra) in public and private potable water supplies have been the subject of study for many years. These studies have shown that high concentrations are usually found only in well waters. The largest single area in the United States where significant radium concentrations have been reported is within a five-state area that includes Minnesota, Wisconsin, Iowa, Illinois, and Missouri. This study summarizes the results obtained from 1,961 water samples collected between 1950 and 1978. 177 U.S. communities, with a total population of 1,442,000 people, were identified as having mean radium 226 concentrations of 3 pCi/L or greater. Of these, 599,000 people in 91 communities are exposed to radium 226 concentrations exceeding 5 pCi/L. One objective of this study was to develop a method for predicting the concentration of radium in well waters based on the well's location, the details of its construction, and the geological structures it penetrates; however, the data suggest that these variables are not accurate predictors of radium 226 concentration in water. Because high concentrations of radium 228 have been found in areas with low radium 226 concentrations and radium 228 is not detected by gross-alpha analysis, it appears that a largescale survey of radium 228 in water is needed. Includes 33 references, tables, figure.