The effects of alternative disinfectants on drinking water quality were examined along with the ability of granular activated carbon (GAC) to remove disinfection by-products and organic contaminants from lower Mississippi River source water. In addition, the study obtained bacteriological information associated with the influent and effluent of each sand and GAC column, and it evaluated the effects of post filtration disinfection with monochloramine and free chlorine. One other objective was to collect water samples for health effects research. To accomplish these objectives, four parallel pilot column process streams were each dosed with a different disinfectant (ozone, chlorine dioxide, monochloramine, and chlorine) and compared with a fifth pilot column stream that was not disinfected. Samples collected from each step in each process stream were analyzed for total organic carbon, total organic halide, 10 volatile organics, 65 solvent-extractable hydrocarbons, 26 chlorinated hydrocarbon insecticides, heterotrophic plate count, total coliforms, and dissolved oxygen.