San Francisco gets its water from the Hetch Hetchy reservoir in Yosemite by way of a 167-mile aquaduct. The aquaduct empties into Crystal Springs Reservoir, a man-made lake in an earthquake rift valley on the San Andreas fault, about 20 miles south of San Francisco. The massive water project was completed in 1934. "[A]s a monument to the engineering marvel that brought Hetch Hetchy water more than 160 miles across California from the Sierra Nevada Mountains to the Bay Area", San Francisco built the Pulgas Water Temple at the site where the Hetch Hetchy empties into Crystal Springs.
It's just north of Filoli.
Note that there was no grate over the viewing pool inside the temple was when I was a kid. You could look right down to see the water rushing in under the temple.
Drunk teenagers jumping into the temple and drowning in the 1970s put an end to that. It's still a neat place to visit.
The aquaduct empties into a canal behind the temple now, instead of underneath it.
There it is: some of the cleanest, best-tasting drinking water anywhere in the United States. San Francisco's water has its own Facebook page.
Crystal Springs Reservoir, and the San Andreas fault, as seen from a freeway rest-stop after lunch.