As populations continue to increase and new water sources become scarcer, the need for water reuse is realized. This technology is needed not only for growing urban centers but also for remote locations such as the summit of Pike's Peak, Colorado, or future Martian habitats. This paper describes a graywater reuse system being developed for the new Summit House on top of Pike's Peak using some of the same unit processes NASA is testing for a closed-loop space habitat. This system will help reduce traffic and labor at Pike's Peak by producing potable water, treating graywater and reusing it on site. The current system consists of hauling potable water to the Summit House in tanker trucks and hauling the graywater back down the19-mile road to the Colorado Springs wastewater treatment plant. NASA wants a long-term test of the reuse design at the Summit because of the harsh conditions faced at an elevation of 14,110 feet, such as low temperatures, low oxygen content and low pressures. The graywater reuse system will consist of an immobilized cell bioreactor, reverse osmosis membranes, and disinfection. This project will provide a working water reuse design that will be beneficial for use in future human space exploration and also in arid regions and remote sites here on Earth. Includes 13 references, table, figure.