Saturday morning I attended the Bay Area Infrastructure Observatory tour of the Santa Clara Advanced Water Purification Center. It's a cool new facility where they're taking waste water and purifying it for reuse (rather than dumping it into the bay).
The tour was interesting and we got to follow water throughout the whole process (from treated waste water in, through various sized filters, and then through uv light).
Here are some photos from the tour:
Waste water intake:
Reverse Osmosis Filters (0.1 nanometers)
Crazy dashboard of the whole system