In many communities, treatment plants collect used water, purify it and send it back into the delivery system, mostly for irrigation and industrial purposes. In 2015 California recycled about 714,000 acre-feet, primarily for landscaping and irrigation. Sixteen percent, about 114,000 acre-feet, was used to recharge groundwater basins.  

Water recycling is often termed a “drought-proof” supply, and state initiatives aim to be reusing about 2.5 million acre-feet annually within a decade.