Diemer Filtration Plant, California

The Diemer Plant (aka The Robert B. Diemer Treatment Plant) is on top of a ridge above Yorba Linda, and is one of the largest filtration plants in the country. It cleans water that comes from the Colorado River Aqueduct, then distributes the water to about 40% of Orange County. Water flows downhill from the plant into the Allen-McCollough Pipeline, a buried pipe which carries water to South County. The rest of Orange County gets its drinking water from groundwater which is replenished through injection wells and percolation ponds along the Santa Ana River.