Commercial structures such as as schools, businesses, and apartment complexes require more sophisticated greywater systems than a typical home would. These systems generally collect greywater in a large holding tank where it is filtered, disinfected, and then is pumped back into the building to either flush toilets or supply a drip irrigation system in a landscape. (greywateraction.org)
At a commercial scale, it is more cost effective to treat the entirety of a buildings waste water than just separating one specific portion of it. (greywateraction.org)
Precedent
The Solaris building in New York treats all the water on site and then reuses it for the toilets in the building. The Solaris building utilizes a membrane bioreactor (MBR) system which treats, stores, and then reuses for toilets, irrigation, and cooling systems. This system has reduced the fresh water taken from the city by over seventy five percent and has also decreased energy costs accumulated through constant pumping. (greywateraction.org)
Another precedent for commercial greywater applications is the the living machine. The San Francisco Public Utilities Headquarters uses a living machine which is a system that uses plants and beneficial bacteria to effectively treat and reuse wastewater through principles of wetland ecology. The building uses sixty percent less water because of the living machine system. (greywateraction.org) (livingmachines.com)
The Tidal Flow Wetland Living Machine incorporates a series of wetland cells, or basins, filled with special gravel that promotes the development of micro-ecosystems. These highly flexible cells may be integrated into exterior landscaping or built into a building or greenhouse. As water moves through the system, the cells are alternately flooded and drained to create multiple tidal cycles each day, much like natural wetlands, resulting in high quality reusable water. The micro-ecosystems within the cells efficiently remove nutrients and solids from the wastewater, resulting in high quality effluent. The final polishing stage, which involves filtration and disinfection, leaves water crystal clear and ready for reuse. Online sensors continuously monitor water quality and chlorine residuals to ensure that reclaimed water is completely safe. (livingmachines.com)
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PUBLIC INTEREST DESIGN: An Introduction 