The restrooms are the vision of Hyphae Design Laboratory of Oakland and its founder, Brent Bucknum, who helped create the celebrated living roof at the California Academy of Sciences in Golden Gate Park. The science behind them is already used in developing countries: solid and liquid wastes are separated, reducing smells and the risk of disease. No toxic chemicals are used, making it possible to eventually transform waste into plant nutrients (although initially, in San Francisco, it would be trucked to waste treatment facilities).

“We have to deal with this lack of public facilities, and the lack of public decency,” Mr. Bucknum said.