The objectives of this study were to: evaluate and compare the accuracy of the first- and second-order models describing chlorine decay as a function of model start time; evaluate and compare the model accuracy for rechlorination kinetics using the first- and second-order model; and, evaluate the predictive ability of the second-order model when fit to a limited set of data. Also, potential implications of applying the second-order model for use in distribution system water quality modeling is discussed. While the first-order model produces adequate results, it is not appropriate in accounting for the changes associated with decreasing reactive material within the water. The second-order model, while still a theoretical simplification, provides a mechanism to account for decreasing reactive material which increases accuracy, particularly where the rechlorination scenarios vary widely with respect to rechlorination doses and times. Additionally, distribution systems are looped systems such that every time two or more links connect, the result is similar to a rechlorination scenario. Therefore, the second-order model might be a more accurate way of modeling chlorine decay in a distribution system water quality model.