The objective of this project was to demonstrate and validate the retrofit of existing buildings with an integrated suite of water efficiency and reuse technologies that support building level cascade of water use thereby reducing potable water consumption. An existing administrative building was retrofit with a cascading water use system that combined the proven technologies of water efficiency with newer, less applied concepts of graywater reuse to provide an optimized, highly efficient system for minimizing potable water use in Department of Defense (DoD) buildings. A new training barracks that was constructed with a building scale graywater reuse system in place was monitored for its ability to meet the project’s performance objectives.

The project considered a range of water saving technologies that building managers could consider. Based on demonstration site factors, the project focused primarily on efficient water fixtures and graywater reuse technologies. Most of the technologies studied were at the bathroom scale, though one building scale system was evaluated as well. For bathroom retrofits, the technologies investigated included 0.5 gallons per minute (gpm) sink faucets with infrared auto-off sensors, an under-sink gray-water reuse system, low flush toilets and/or alternate toilet sensor settings, and 2 gpm showerheads in building locker rooms. The building scale system that was investigated was a graywater reuse system that treated graywater from sinks and showers such that it could be reused for toilet flushing. The primary metric for the project was to reduce water demand at the building level by 30%. Impacts on operations and maintenance, as well as energy consumption, were also measured.

In the case of a building comprised primarily of office space, conservation fixtures achieved a reduction in overall facility water use of 7% as compared to the target rate of 30%. An additional 7% reduction was realized by adjusting toilet automatic flush mechanisms, for a total building potable water reduction of 14%. Several factors contributed to this lower than projected reduction. First, faucets and showers represented a small fraction of the building water demand, which included specialized research facilities with high water needs, so associated improvements had limited overall impact. Second, recommendations for toilet retrofits were limited to flush valve sensor adjustments, with toilet and flush valve replacements planned by the facility for an upcoming remodel. Despite this low figure, the faucet and shower retrofits paid for themselves in less than a year with the cost of water alone. Lastly, the undersink graywater system did not recover enough water from the sinks to support the toilet flushing.