Water recycling, also known as reclamation or reuse, is a reliable, economically feasible and environmentally sensitive means to maximize California's water resources and reduce the demand on freshwater systems. Recycling programs mimic the way nature purifies water and treat wastewater so that it can be safely used to irrigate landscape, golf courses, crops and freeway medians, replenish groundwater basins, flush toilets and act as a barrier to seawater intrusion. Recycled water is also increasingly being used by industry in cooling processes, new home construction and for other purposes.
California is among the major players worldwide in water recycling. There are over 250 water recycling plants currently operating in the state, with more planned for the future. According to the California Department of Water Resources, the state recycles anywhere from 450,000 acre-feet to 580,000 acre-feet of wastewater annually, which is almost three times the amount recycled in 1970.
About two-thirds of the state's recycled water is used for irrigation, with about 46% used for agriculture and another 21% used for landscaping. About 14% is used for groundwater recharge, while 19% goes to all other uses.
Experts say an additional 1.4 million acre-feet to 1.7 million acre-feet of wastewater could be recycled by 2030. That level of recycling will go a long way toward meeting the needs of the 17 million additional residents California will have by 2030.
Projects Around the State
Many large recycling projects have been completed over the past decade. The list includes the South Bay Water Recycling program, which distributes recycled wastewater to more than 400 customers in the San Jose area; Irvine Ranch Water District’s ground-breaking dual water system, which supplies recycled water to commercial high rises for use in flushing toilets and urinals; a project by West Basin Municipal Water District that distributes recycled water to more than 210 customers; Monterey County Water Recycling Projects, which provide recycled water for agricultural irrigation to help ease demands on an overdrafted groundwater aquifer; and the Padre Dam Water Recycling Facility, which was expanded to recycle 2 million gallons/day for turf irrigation at parks, golf courses and other commercial and industrial facilities.
Among the most sweeping new projects to come on line is the Groundwater Replenishment System developed by Orange County Water Distirct and the Orange County Sanitation District. The award-winning project takes highly treated wastewater previously discharged into the ocean and subjects it to further treatment, including microfiltration, reverse osmosis and ultraviolet disinfection. The purified water is pumped to spreading ponds near the Santa Ana River for percolation into the groundwater basin, with some injected along the coast as a barrier to seawater intrusion.
The Groundwater Replenishment System produces 70 million gallons per day, or up to 25.5 billion gallons of water per year. That is enough to meet the needs of 500,000 people.
In the San Diego region, 16 water agencies are collectively using over 32,300 acre-feet of recycled water annually to meet the region’s water supply demand. Examples of local recycled water projects include the City of Carlsbad’s new recycled water treatment and distribution system that will deliver approximately 3,000 acre-feet per year of recycled water to customers located in that seaside community. In the southern portion of San Diego County, the Otay Water District is constructing a distribution system to deliver an estimated 5,000 acre-feet per year of recycled water by 2030 purchased from the City of San Diego’s South Bay Water Recycling Plant.