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The lifecycle of toilet water at the PUC

Hana Baba
The plants outside the PUC

You may have walked by the beautiful green plants growing outside the San Francisco Public Utilities Commission on Polk Street and not thought much about them. But these plants get their nourishment from our waste.

Along the outer perimeter of the building, there are rectangular planters that are irrigated by reused waste water, or ‘black water’. Black water includes toilet water, urinal water, bathroom and sink water.

The plants also work to treat the water as it flows through them by absorbing the nutrients in the waste. After treatment comes disinfection with ultraviolet lights and chlorine. Then, the water is redirected back to the bathroom for reuse.

Paula Kehoe, the Director of Water Resources at the San Francisco Public Utilities Commission, said they have saved 65% of their water as a result of this process.

“We’re very proud because we are using recycled water and we’ve managed to save over 1.5 million gallons of potable drinking water, and we use recycled water instead to flush our toilets,” she said.

It takes 48 hours once the water goes through the living machine and back up into the toilets.

Hear the life cycle of bathroom water by listening to the story above.

Crosscurrents KALW archives