At the old North Carter Lake Direct Filter Plant, put into service in 1962, capacity has had to be reduced by 25% to ensure treatment compliance with state and federal regulations. To regain this capacity and recover performance, membrane technology was chosen for the improvements. Membranes were pre-bid and USFilter - Memcor submerged membrane system was the successful bidder. In order to validate the expected performance of the new membrane technology, pilot tests were performed. The primary objective of the pilot study was to confirm flux, recovery, backwash and CIP interval, as well as demonstrating required filtrate quality. In a pilot study over more than 6 months most of the parameters were proven. However, the manufacturer fell short to demonstrate consistent achievement of the expected CIP intervals during the coagulant addition phase. Through the testing of an alternative coagulant the anticipated CIP intervals were validated, total organic carbon (TOC) removal was accomplished and the proof pilot was successfully completed. Collected data during the pilot trials is presented and discussed. Soon after the pilot trials ended, construction of the new water treatment facilities started. Implementation of the concept began in winter 2005/2006 and continued until winter 2006/2007. Currently the system is in a 60 day startup phase with a subsequent 60 day proof phase. Includes 2 references, tables, figures.