The objectives of this study were to investigate the impact of backwashing and desorption on the breakthrough behavior of natural organic matter and disinfection byproduct precursors and to develop a model to account for adsorption, hindered back diffusion and backwashing. The study was divided into the following specific objectives: examine the impact of backwashing on NOM adsorption; investigate the desorption of NOM by a concentration gradient; model the experimental adsorption and desorption data; model the experimental backwashing data; modifying existing models to include the effect of hindered back-diffusion; and apply the modified model to NOM desorption.