Trihalomethanes are formed during drinking water treatment when the free chlorine used as a disinfectant combines with trihalomethane precursors, mainly humic materials, present in the water. One approach to lowering trihalomethane concentrations in finished drinking water is by switching from free chlorination to an alternative disinfection process. The alternative processes vary widely in their tendencies to form byproducts other than trihalomethanes, the state of knowledge of their respective byproduct production, their disinfecting capabilities, and the engineering considerations associated with their application as a treatment process.