This paper describes the use of membranes to reduce disinfection byproducts and their precursors from one surface water and several groundwater sites located in Florida. The membrane pilot plant studies that are described here are part of two separately funded projects. The first is a three-year multi-phased project sponsored by the Pinellas County Water Utility System. This particular phase was to evaluate membrane processes as a future water treatment option. The second is a three-year project funded by the USEPA Drinking Water Research Division to evaluate disinfection byproduct precursor reduction by membranes. This paper also addresses water production or mass transfer coefficients of the membrane pilot plants the groundwater sites.