One of the largest water utilities in the United States has changed from chlorine in its disinfection process to chloramines for controlling the formation of trihalomethanes. A study was conducted to determine if the conversion from free chlorine to chloramine disinfection was feasible for the water system. Technical aspects of chloramination were also addressed before the actual change took place on Nov. 5, 1984. This article recounts the issues that were evaluated prior to making the change to chloramines.