The potential for bacterial regrowth increases in many waters after ozonation. This additional regrowth potential is related in some cases to an increase in the biodegradable portion of the total organic carbon, or the biodegradable organic carbon (BDOC). Application of chlorine to control additional bacterial regrowth results in DBP formation, which must be minimized as much as possible to meet the proposed regulations. Ozonation alone has not consistently produced reductions in DBP concentrations. Thus, an additional treatment step after ozonation, such as biological treatment to remove biodegradable organic carbon, may be necessary if treatment goals are to be met. This research measured the effect of removing the biodegradable organic carbon in one surface water on chlorine residuals, DBP concentrations, and bacterial regrowth, over a range of ozone doses.