San Francisco recycled water programme pushing wastewater towards drinkability

22-11-2019
wastewater treatment,water treatment,recycled water,drinking water

The city of San Francisco could be drawing on a new source of drinking water that is a recycled version of what’s being flushed down toilets.

By design, the San Francisco Public Utilities Building is exceedingly green. It opened in 2012 and for years the building has been recycling its wastewater for things like flushing the toilets. Now, that water can be consumed.

“Everything that’s connected in this room to the transparent pipe is part of our research project,” explained Manisha Kothari, Project Manager for the SFPUC.

Down in the bowels of this building that houses some 900 employees, you will find the equipment that treats all of their wastewater.

The rain that falls on the roof and the water that comes out of the bathrooms has all be getting a first wash through the building’s engineered wetlands system that can be seen in the lobby. Now, that water is being carried over the threshold of drinkable.

“What we start with is the recycled water,” said Kothari. “That’s the water that comes into our system. Then we put it through ultra-filtration. Then we put it through reverse osmosis, that’s our second and major step. Finally, we put it through our UV disinfection.”

The resulting water isn’t just tested for safety; a detailed record is made of everything that comes out. The water is so stripped down by the time they’re done, it would actually need minerals being put into the actual water system.

“If we were to use it for a different application, absolutely,” Kothari explained. “If we were to put it into our distribution system, we would want to condition it that water before we did that.”

“This is a research project,” says Paula Kehoe, Director of Water Resources for the FPUC. “We’re not going to be delivering purified water tomorrow. What we’re doing is research to ensure the safety of this water.”

The city hopes this project is just the beginning of a better understanding of how this technology may be used in the future.