The purpose of this research is to develop a better understanding of disinfection byproduct precursor (DBPP) removal by enhanced softening to assist water utilities in complying with existing and proposed SDWA regulation. Specific objectives are to: determine the degree of improvement in precursor removal that can be achieved by enhanced softening, with special attention to the effectiveness of increasing lime dosage, addition of coagulant aids, and precoagulation; evaluate differences in DBP formation potential among raw water, water treated under normal (unenhanced or baseline) conditions, and water treated under enhanced softening conditions; compare the performance of enhanced lime softening and enhanced coagulation for removing DBPPs from source waters having differing characteristics; identify and evaluate benefits, costs, and potential problems associated with enhanced lime softening; and compare the DBPP removals achieved by bench-scale tests with those of full-scale softening plants.