In downtown San Francisco, in a cavernous garage that was once a Honda dealership, a gleaming white-and-blue appliance about the size of a commercial refrigerator is being prepared for transport to a hotel in Los Angeles.

There, this unit, called a OneWater System, will be installed in the basement, where its collection of pipes will take in much of the hotel’s graywater — from sinks, showers, and laundry. The system will clean the water with membrane filtration, ultraviolet light, and chlorine, and then send it back upstairs to be used again for nonpotable uses.

And again. And again.

“There is no reason to only use water once,” said Peter Fiske, the executive director of the National Alliance for Water Innovation, a division of the Lawrence Berkeley National Laboratory, in Berkeley. Just as natural systems use and reuse water repeatedly in a cycle driven by the sun, he said, “we now have technologies to enable us to process and reuse water over and over, at the scale of a city, a campus, and even an individual home.”

While centralized water reuse for nonpotable purposes has been around for decades, a trend called the “extreme decentralization of water and wastewater” — also known as “distributed water systems,” or “on-site” or “premise” recycling — is now emerging as a leading strategy in the effort to make water use more sustainable.

The concept is to equip new commercial and residential buildings as well as districts, such as neighborhoods and universities, with on-site recycling plants that will make water for nonpotable use cheaper than buying potable water from a centralized source. By driving down demand for potable water, which is costly to filter, treat, and distribute, the units will help manage water more efficiently. It is, many experts believe, the future of water. Eventually it’s hoped that buildings will be completely self-sufficient, or “water neutral,” using the same water over and over, potable and nonpotable, in a closed loop.

It’s not just a pipe dream. Proof of concept is unfolding in San Francisco, which in 2015 required all new buildings of more than 100,000 square feet to have on-site recycling systems. So far, six blackwater and 25 graywater systems are using the technology, and many others are in the works. (Blackwater comes from toilets, dishwashers, and kitchen sinks; graywater comes from washing machines, showers, and bathtubs.) The headquarters of the San Francisco Public Utilities Commission has a blackwater system, called the Living Machine, that treats its wastewater in engineered wetlands built into the sidewalks around the building, then uses it to flush low-flow toilets and urinals. The process reduces the building’s imported potable supply by 40 percent.

Recycling graywater alone can save substantial amounts of water. Using it to flush toilets and wash clothes reduces demand for new water by about 40 percent. Using recycled water for showers would eliminate another 20 percent of water demand, though the safety of that practice is being researched and is not yet permitted in San Francisco.

To demonstrate its technology, Epic Cleantec, a water recycling company, has even brewed a beer called Epic OneWater Brew with purified graywater from a 40-story San Francisco apartment building.

Read the full article about water recycling by Jim Robbins at YES! Magazine.