Los Angeles set to build facility to transform wastewater into clean drinking water

Los Angeles will soon begin building a $740-million project to transform wastewater into purified drinking water in the San Fernando Valley, expanding the city’s local water supply in an effort to prepare for worsening droughts compounded by climate change.

The city plans to break ground next month to start construction of new facilities at the Donald C. Tillman Water Reclamation Plant in Van Nuys. When completed, the facilities will purify treated wastewater and produce 20 million gallons of drinking water per day, enough to supply about 250,000 people.

The drinking water that the plant produces will be piped 10 miles northeast to L.A. County’s Hansen Spreading Grounds, where it will flow into basins and percolate into the groundwater aquifer for storage. The Los Angeles Department of Water and Power will later pump the water from wells, and after additional testing and treatment, the water will enter pipes and be delivered to taps.

“It’s a major step forward for the city,” said Jesus Gonzalez, the DWP’s manager of water resources. Through this project, he said, the city will start using recycled water as a “new source of sustainable, drought-proof drinking water supply.”

L.A. has been recycling wastewater for decades but has previously used the treated water for outdoor irrigation in areas such as golf courses and parks. With the new facility, which is scheduled to be finished in 2027, the city will for the first time start using purified recycled water as part of the drinking water supply.

The initiative, called the L.A. Groundwater Replenishment Project, was approved last month by the city’s Board of Water and Power Commissioners. L.A. Mayor Karen Bass and other city officials have called it a key piece of their efforts to invest in local water supplies and reduce reliance on imported supplies that are growing less reliable with climate change.

The project has been in the making for three decades. The city built part of the infrastructure, including the pipeline and pump stations, in the 1990s, but the effort was derailed in 2000 when debate erupted over what opponents and newspaper headlines called a “toilet-to-tap” project. The issue was caught up in a mayoral campaign and a 2001 ballot measure calling for the Valley to secede from the city. The plan was then set aside, delaying it for years.

In the meantime, Orange County moved ahead to develop its Groundwater Replenishment System, the world’s largest project of its kind, which is now recycling 130 million gallons of water a day. The system purifies wastewater using a three-step advanced treatment process, and the water then percolates and is injected into the groundwater basin, where it becomes part of the supply.

“We are going to build the same type of treatment system that Orange County has now employed for 15 years successfully,” Gonzalez said.

The extensive treatment and purification process, in addition to testing, will ensure that the drinking water will be “incredibly safe once it’s pumped out and served to our customers,” he said.

The Tillman plant is one of four wastewater treatment facilities operated by L.A. Sanitation and Environment.

Currently, treated effluent from the plant is released into the Los Angeles River in the Sepulveda Basin, providing a significant portion of the river’s flow in the area during dry times. The water recycling project was designed so that even as purified water is piped away, a stream of treated wastewater will still flow to sustain the L.A. River and its wildlife habitat, Gonzalez said.

To help cover the cost of the new construction, the city has secured more than $400 million from the state and federal governments and the Metropolitan Water District of Southern California.

The project is long overdue, said Mark Gold, director of water scarcity solutions for the Natural Resources Defense Council.

“This was recycled water that should have been in the city’s system 20 years ago, but the politics of water stopped it,” Gold said. “It’s great that it’s finally happening and will be completed quickly.”

City leaders are investing in the facility while also planning a much larger effort to turn sewage into purified drinking water. Through a project called Pure Water Los Angeles, they plan to treat recycled water from the Hyperion Water Reclamation Plant, the city’s largest wastewater treatment facility, and use that water — as much as 230 million gallons a day — to provide about a third of L.A.’s drinking water supply.

UCLA researchers recently analyzed plans for the project, which previously was known as Operation Next, and found it would significantly bolster local water resilience and bring long-term economic benefits by dramatically reducing risks of water shortages.

Researchers at UCLA’s Luskin Center for Innovation examined about 100,000 potential scenarios, including shortages caused by droughts or major earthquakes that could rupture aqueducts and cut off outside supplies. They found in their report, which was funded by the DWP and released this week, that having Pure Water L.A. online would significantly increase the resiliency of the city’s drinking water supply in all scenarios.

“Any way you slice it, our estimates are that the benefits are going to vastly outweigh the costs,” said Gregory Pierce, research director of the Luskin Center.

In recent years, Los Angeles has been importing nearly 90% of its water, drawing on supplies from the Eastern Sierra, the Sacramento-San Joaquin River Delta and the Colorado River.

“Because climate uncertainty will be the largest driver of the city’s water shortage, the city must adapt by developing more local, reliable supplies,” Pierce said. “It’s worth making that investment even though it’s a high cost up-front.”

The cost of Pure Water L.A. has yet to be determined. In recent years, various initial estimates have ranged from $6 billion to $20 billion.

DWP is currently preparing a plan outlining options for the project. City officials have said it will help move L.A. toward a goal of recycling 100% of the city’s wastewater by 2035.

While much of the purified water is slated to be used to replenish groundwater basins, DWP also plans to consider incorporating “direct potable reuse,” which involves delivering purified water directly to customers or mixing it with other supplies.

Last year, California’s State Water Resources Control Board adopted nation-leading regulations allowing water utilities to begin developing facilities that put highly treated recycled water straight into drinking-water supplies. Gonzalez said the DWP will soon open a small demonstration facility at the department’s complex near Griffith Park to develop treatment technologies and monitoring methods that ensure protection of public health.

As the city turns to developing what would be the nation’s largest water recycling project, various questions have yet to be answered, including where the purification facilities will be located, how the distribution system will be designed, and what the time frame for construction will be, Gold said.

“A clear direction and implementation plan for Pure Water L.A. is still missing,” he said.

Gold said another key question is how the city’s project at the Hyperion plant in Playa Del Rey will fit with the Metropolitan Water District’s separate plan for another recycling facility in Carson, called Pure Water Southern California. According to the MWD’s latest estimate, that project will cost $8 billion at full build-out and produce 150 million gallons of water daily.

“My concern is, are we running out of time to make those decisions so that we’re not a completely separate system,” Gold said. “Because it is so important, not only for L.A. but for the region, for the systems to be integrated.”

He said it’s important for L.A. officials to decide quickly because the MWD’s project is currently at least five years ahead of the city’s project.

“There are still way too many questions, in light of the urgency of making L.A. a more climate resilient city when it comes to water supply,” he said.

Others are raising additional questions about the city’s approach.

Melanie Winter, who leads a nonprofit called the River Project and advocates for nature-based changes in the L.A. River watershed, said she is glad the city is following through to complete the water recycling project in the San Fernando Valley, but that L.A. should also focus more on managing its stormwater better. She has advocated for removing concrete and pavement in parts of the watershed to naturally capture rainwater and recharge groundwater.

“We have to have a larger portion of our groundwater recharge coming from managing rainwater, in getting rid of impervious surfaces and letting it infiltrate,” Winter said. “We have to have stormwater as a bigger part of that equation.”

As for future water recycling projects, Winter said she thinks Los Angeles should focus on developing various smaller-scale facilities to ensure redundancy, rather than planning to rely on a large centralized system that she argues would be vulnerable to failure due to an earthquake or other hazards. She pointed out that the existing infrastructure at the Hyperion plant has a history of failures and sewage spills.

“We need to be thinking in a more distributed fashion than the centralized systems that are currently being imagined and proposed,” Winter said. “If you have a decentralized network, then it’s a lot more stable. And they haven’t been considering that in the ways in which they should.”