Long duration missions in space will require regenerative processes to recover water for crew reuse. Membrane processes are attractive as a primary processor in water recovery systems (WRS) because of their design simplicity, low specific energy requirements, small size, and high water recovery. However, fouling has historically been regarded as a disadvantage of membrane-based processes. This fouling is often caused by micelle buildup on the membrane surface by high-molecular-weight organics (e.g., from soaps and laundry detergents).This paper describes a two-stage fouling-resistant ultrafiltration (UF)/reverse osmosis (RO) prototype subsystem, which was designed and constructed for a WRS in the Life Support Systems Integration Facility (LSSIF) at NASA Johnson Space Center (NASA/JSC). The first stage of the subsystem is a tube-side-feed hollow-fiber UF module that removes contaminants that tend to foul spiral-wound modules. The unique flow patterns in this module minimize the build-up of foulants on the membrane surface and allows the use of innovative system designs and operating modes that prevent fouling. The second stage is a spiral-wound RO module that removes the remaining contaminants.During testing, the prototype subsystem performed as designed, processing 92 liters (202 lb) of wastewater in 8 hours or less, at a water recovery of 94%. The prototype subsystem produced a permeate with less than 20 ppm total organic carbon (TOC).The design of the prototype UF/RO subsystem, the process flow diagram, and the control strategy used to obtain long term, reliable performance are described. Also, performance data for the UF/RO subsystem are presented.