On a sunny day in December, I visit a shiny, sterile water-processing facility nestled in the hills of northern San Diego. Sheltered by an ugly cream-colored roof but lacking walls, the workings of this oversize chemist's laboratory glisten in the warm winter sun. Visible from every angle are row on row of silver tubes and canisters of various shapes and sizes and great gray metal vats of concealed liquid. As my tour of the small plant comes to a close, I am presented with a challenge: to identify, by sight, the contents of three large glass bottles, spaced evenly on a table before me and filled with clear fluids. The first bottle seems to have a slight yellow hue. The second is colorless. The third has the brilliance of a well-cut diamond.
I complete my task with ease, identifying the contents, in order, as regular tap water, recycled wastewater from a conventional treatment plant and highly purified toilet bowl water, produced on-site. I am surprised not just by my overwhelming urge to drink the treated sewage but also that I cannot. “We're not allowed to taste it or to have visitors taste it,” says a serious Marsi A. Steirer, my guide and deputy director of the City of San Diego Public Utilities Department, which runs the plant.