Reuse system turns wastewater at San Francisco high-rise into clean water, soil, energy
SAN FRANCISCO (KPIX) -- For many, Tuesday's rain was simply a reminder of how dry things have been. Repeated droughts are changing attitudes about how we think about a resource we once took for granted. now, a new generation of buildings is coming to San Francisco that reimagine how water is used.
"There's no reason why we should be taking fresh water from Hetch Hetchy to flush our toilets in downtown San Francisco," said Aaron Tartakovsky, founder of a company called Epic Cleantec.
His company operates a self-contained water treatment and recycling system for a 40-story apartment building on Mission Street, simply known as "Fifteen Fifty." When it opened in 2020, it was the first to comply with a 2016 law requiring large new buildings to have a water re-use system.
Tartakovsky said it is still the only building in the city with such a system and after two years of testing, it has become a model for what's possible in water conservation.
"By reusing 7,500 gallons per day, or up to two-and-a-half million gallons a year," he said. "That's two-and-half million gallons less of fresh drinking water they have to bring into this building."
Water from sinks, showers and laundry rooms is carried in a separate pipe system to a 10,000-gallon holding tank in the basement. From there, the water is sent to the filter room where it first sits in an aeration tank, to let microbes digest organic matter. Then that water is pushed, under pressure, through permeable membranes where it is finally disinfected with bleach and UV light. When it's finished the ultra-cleaned water is sent back up into the building to flush toilets and urinals.
"So, the water that's going to be entering into people's toilets or used to flush urinals, you would never know the difference," said Tartakovsky.
They're also experimenting with collecting and filtering water from toilets. The solids are sent to a facility across the street where a composting system turns it into a sweet-smelling fertilizer for the courtyard garden. Tartakovsky said it's even possible to capture energy from warm wastewater. It's an entirely new way of thinking about what we've been sending down the drain.
"Buildings bring water in and they send water out," said Tartakovsky. "We call that 'wastewater.' What we're showing here is that the 'waste' in wastewater, is not really waste at all, that we can turn wastewater into clean water, into soil, into energy, into all these amazing things that we just don't typically think of."
Currently, San Francisco mandates any new building over 100,000 square feet to have a water re-use system. The legislature is considering similar requirements for buildings statewide. It's happening now at Fifteen-Fifty, but that trickle will soon become a flood as builders include treatment and recycling systems to meet changing laws, and changing attitudes. The "Re-use Revolution" has begun.
