Abstract: In field operating environments, military units must ensure access to a critical water supply to maintain mission readiness. Increasing complexity of logistics and costs to transport water and climate change are driving the development and demonstration of water treatment units. The treatment unit described uses ultrafiltration (UF) and reverse osmosis (RO) membrane technologies with a disinfection step to treat low-strength graywater from shower facilities at Camp Shelby Joint Force Training Center in Hattiesburg, Mississippi. Samples were collected from human shower sampling events. During the demonstration, greater than 100,000 gal. of graywater were treated, supplied by two battalion training rotations over a 6-month period. Characterization of the source graywater continued throughout the system demonstration. Based on the literature, these are among the largest source-separated graywater sampling events to date. The combined treatment train of UF/RO met all compliance metrics for all analytes of interest for potability and met nonpotable metrics except for special use cases in three states. Both the quality of the treated water and the effective volume gains from an 85% multiplier effect directly support DoD water sustainment goals for both installations and operational environments.