Use of membrane treatment for particle and microorganism removal is likely to increase in the future. This paper describes the advantages of the ultrafiltration (UF) and microfiltration (MF) technology which have been demonstrated through numerous research and pilot studies. Microfiltration and ultrafiltration have been successfully applied as a treatment technique in order to satisfy the filtration, turbidity, and microbial control requirements of the Surface Water Treatment Rule (SWTR). Ultimately, the economics, reliability, scalability, and operational performance of the process will determine the degree to which the treatment process is used. For the interim, based upon the work performed to date, it is apparent that MF and UF membrane filtration processes will be considered as the Best Available Technology (BAT) for turbidity, particle and microorganism removal.