Thirty years ago, USEPA was starting to assess the capabilities of various alternative drinking water treatment processes for reducing the consumer's exposure to trihalomethanes and organic carbon compounds. This pilot plant study, using Missouri River water, was one of the first to directly compare the use of chlorine versus chloramine for reducing the formation of trihalomethanes while maintaining disinfection capability. Over the ensuing generation, chloramine has become the dominant means for disinfection of surface waters throughout the United States.