In order to comply with the SWTR, utilities will need some method to assure maintenance of disinfectant residuals throughout their distribution systems. Computer based mathematical models offer great promise as a tool for predicting disinfection residuals and aiding the utility operator in optimizing the operation of his disinfection system so as to assure maintenance of an acceptable disinfectant residual. This paper describes research to develop and refine kinetic relationships describing chlorine decay in drinking water distribution networks with the primary objective of developing a refined computer model usable by water utilities.