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The Metropolitan Water District of Southern California

A New Source of Water for Southern California

Water is too precious to use just once. So the Metropolitan Water District of Southern California is making a major investment in a potential water recycling project that will reuse water currently sent to the ocean. The Regional Recycled Water Program, a partnership with the Sanitation Districts of Los Angeles County, will purify wastewater to produce high quality water that can be used again. The program will start with a demonstration facility and could eventually become one of the largest advanced water treatment plants in the world.

The demonstration facility will take treated wastewater from the Sanitation Districts' Joint Water Pollution Control Plant in Carson and use both tried and tested water treatment technologies, employed across the globe for decades, and innovative processes to ensure the water is safe to reuse.

View program brochure

Project Benefits

​The Regional Recycled Water Program:

  • Uses region's largest untapped source of treated wastewater, currently sent to the ocean.

  • Produces a drought-proof source of water, readily available rain or shine.

  • Prepares the Southland in the event of a catastrophic earthquake by increasing local water supplies.

  • Replenishes groundwater basins, which provide 30% of Southern California's water supply and have seen levels drop to historic lows in recent years.

  • Helps meet needs of region's growing economy and population at a cost comparable to other local water resources.

  • Frees up imported water currently used for replenishment for other uses, like storage for future droughts.

  • Helps ensure regional water reliability through diversifying sources, in addition to conservation, local supply development and imported water.

How it Works

​The process begins with wastewater discharged from homes, businesses and industries. After the wastewater has been cleaned and treated, it flows to an advanced water treatment plant where it is further purified. The water then replenishes groundwater basins and is eventually pumped up, disinfected and used again.

The Advanced Treatment Process
At the Regional Recycled Water Advanced Purification Center, the treated wastewater will go through a three-stage purification process to make it safe for reuse.

Starting Small and Scaling Up

The Advanced Purification Center is a demonstration facility that will generate information needed for the potential future construction of a full-scale recycled water plant. It uses a unique application of membrane bioreactors designed to significantly increase efficiency in water recycling. Scientists and engineers will test the process to ensure the resulting purified water meets the highest water quality standards. Once approved by regulators, this innovative process could be used throughout California and even applied around the globe.



A 500,000 gallon/day demonstration facility

Construction Cost: $17 million

Timeline: Under construction; operation begins late 2018



A full-scale facility would produce up to 150 million gallons daily, enough to serve more than 335,000 homes. Purified water would be delivered through 60 miles of pipelines to 4 groundwater basins in Los Angeles and Orange counties. These basins supply water to 7.2 million people.

Cost: $2.7 billion to build, $129 million annually to operate, resulting in a water cost of $1,600/acre-foot, similar to other new water supplies.

Timeline: 11 years to design and build, once approved

Our Partner

​The Sanitation Districts of Los Angeles County is a regional public agency consisting of 24 independent special districts serving more than 5.6 million people in 78 cities and the unincorporated territory within Los Angeles County. The Sanitation Districts protect public health and the environment through innovative and cost-effective wastewater and solid waste management and, in doing so, convert waste into resources such as recycled water, energy and recycled materials.

The Sanitation Districts operate 11 wastewater treatment plants. The Joint Water Pollution Control Plant in Carson is the largest of these plants and one of the largest in the country.

Learn more about the Sanitation Districts.

Read about the Joint Water Pollution Control Plant.


Regional Recycled Water