Recently, there has been considerable interest and concern over the presence of halogenated organic compounds in potable water. The carcinogenic nature of several of the halogenated compounds has been demonstrated in the laboratory, using high concentrations and laboratory test animals, though no direct cause-and-effect link with cancer in man has yet been established. A 1974 study of New Orleans drinking water (1) and studies by Rook(2) and Beller, et al.,(3) showed halogenated organic compounds in drinking water that were not present in the raw water.