This paper describes the continued development of a non-phase-change waste-water subsystem for use in the planned manned space station. Comparisons of various membrane-based technologies when operated side by side on feed solutions of synthetic wash water are presented. The effects of soap type and operating temperature on membrane-module performance were determined. A preliminary ranking of these modules indicated that several of the reverse-osmosis and ultrafiltration technologies are excellent candidates for use in the subsystem. At this time, a hybrid system configuration consisting of a first-stage ultrafiltration module followed by a second-stage reverse-osmosis module appears to be the most appropriate for use in the subsystem.