The Terminal Island Water Reclamation Plant (TIWRP) at LA Sanitation and Environment is a global trailblazer in water reuse, harnessing recycled water to safeguard its groundwater reserves against saltwater intrusion and meet the city’s growing water needs. In this article, Lance Thibodeaux, division manager for the Terminal Island water reclamation division at LA Sanitation and Environment, describes Terminal Island’s industry leading water reuse program and its long-time partnership with Xylem.
The City of Los Angeles is a global leader in water reuse, deploying advanced recycled water solutions to help meet the city’s growing demands and tackle one of its toughest challenges: groundwater depletion.
L.A.’s ecosystem struggles to naturally replenish its groundwater reserves due to persistent drought and growing water demand. According to a study by the Stanford Doerr School of Sustainability, deep aquifers in the L.A. area only regained about 25% of the groundwater lost since 2006, despite the historic rainfall levels of 2023 and Hurricane Hilary. This limited recharge puts groundwater supplies at risk of saltwater intrusion and contamination.
At the heart of L.A.’s water reuse strategy is the Terminal Island Water Reclamation Plant (TIWRP), operated by the City’s Department of Public Works Bureau of Sanitation (LASAN). As one of the most advanced water reuse facilities in the world, TIWRP plays a critical role in protecting the city’s groundwater resources, reducing reliance on imported water, and meeting some of California’s most stringent wastewater discharge regulations.
Below is an interview with Lance Thibodeaux, division manager for the Terminal Island water reclamation division at LA Sanitation and Environment where he describes Terminal Island’s industry leading reuse program and its long-time partnership with Xylem.
Why did Terminal Island implement water reuse as part of its water supply strategy?
The motivation for the City of Los Angeles, and specifically the Terminal Island plant, to prioritize water reuse began in the mid-1970s. As a result of the federal Clean Water Act and stricter state regulations, the Los Angeles Regional Water Quality Control Board put new policies in place to prevent the facility from discharging into Los Angeles Harbor.
City leaders launched a long-term strategy to determine the best use of Terminal Island’s effluent, weighing traditional ocean outfall against a more forward-looking option: water reclamation. Reuse emerged as both the most economical and environmentally responsible choice—one that would not only meet regulatory requirements, but also create a local, drought-resilient supply for nearby industrial and harbor-area customers.
By 2006, Terminal Island’s Advanced Water Purification Facility was producing 5 million gallons of highly purified water per day. A major upgrade in 2018, expanded production to 12 million gallons a day of advanced treated water, making Terminal Island the first publicly owned treatment works to recycle its entire flow—a real water reuse and innovation success story.
How does the City of L.A. use the recycled water that Terminal Island produces?
While much of Los Angeles’ water supply comes from other parts of the state and the Colorado River—sources that are increasingly strained by drought and extreme weather. As imported supplies become more expensive, local groundwater has become a critical resource for the city’s long-term water security.
Yet, these groundwater reserves face challenges of their own. Many aquifers in Southern California cannot naturally replenish themselves fast enough to meet the needs of a growing urban population. Decades of over pumping and drought have reduced groundwater storage capacity and increased the risk of saltwater intrusion, which can contaminate groundwater supplies.
To combat this threat, the city creates seawater barriers by injecting recycled and imported water deep into underground aquifers to block saltwater intrusion and recharge local groundwater reserves. Terminal Island’s advanced treated water is injected into the Dominiguez Gap Barrier near L.A. to safeguard water supply for 130,000 L.A. residents. Recycled water from Terminal Island is also being used to supply industrials in the L.A. Harbor area, including a major refinery.
What advanced treatment technologies make water reuse viable for Terminal Island?
At Terminal Island, we perform full tertiary treatment to produce highly pure potable water. The advanced treatment consists of microfiltration and reverse osmosis, followed by an innovative advanced oxidation process (AOP) from Wedeco, a Xylem brand. The customized solution, validated through extensive pilot-scale testing at the plant, is the world’s first greenfield AOP design using ultraviolet (UV) light with chlorine for indirect potable reuse.
This approach has been groundbreaking because it allows the plant to utilize its existing chlorination facility without having to add any new chemicals and reduce life-cycle costs compared to the other types of AOP, while complying with California’s strict groundwater recharge regulations.
What does the next 10 years of water reuse strategy look like for Los Angeles?
Recycled water is at the heart of our city’s strategy to build resilience and long-term water security. Today, LASAN’s four reclamation plants can produce 580 million gallons of recycled water per day, and there are ambitious plans underway to continue to scale.
At Terminal Island, our focus is on optimizing advanced treatment operations—improving uptimes, training and developing staff, and maintaining compliance—to maximize overall impact. Our partner agency, the Department of Water and Power, is finalizing the distribution system for the recycled water, as well as customer retrofits, to ensure that 100% of the advanced treated water coming from our facility will have an end user.
The Donald C. Tillman Plant has began construction of an advanced water purification facility to help recharge the San Fernando Groundwater Basin, support non-potable reuse, and add to L.A.’s future drinking water supply.
Meanwhile, the Hyperion Water Reclamation Plant, the largest in Los Angeles, is piloting new technology to support its goal of recycling 100% of its treated water by 2035. Treating an average of 260 million gallons of wastewater each day, Hyperion’s transformation will mark a major milestone in Los Angeles’ journey toward a fully circular, sustainable urban water system.
What advice do you have for another utility that’s just beginning its water reuse journey?
Start by learning from peers. Connect with other utilities that have had success adopting reuse at a similar type of facility. There's a lot to learn from talking to others who have already learned through their experiences.
Embrace piloting. Pilot testing in water reuse helps reduce risk, optimize design, evaluate technologies, and improve operational efficiency before full-scale implementation.
Stay current on changing regulatory requirements. Water reuse requirements are constantly evolving, so keeping up to date ensures your facility remains compliant while maximizing operational flexibility.
Incorporate expert guidance. Engaging consultants to get an industrywide perspective on evolving technologies and compliance trends will help you make informed, forward-looking decisions.
Finally, you can be innovative and practical at the same time. If you keep your focus on your customers, and work with best-in-class solutions and proven partners, you can achieve truly transformative benefits for your community.
Pure Water Los Angeles: Looking to the future
Pure Water Los Angeles (PWLA) is a forward-thinking water source program and partnership between LASAN and LADWP planned to produce up to 260 million gallons of purified recycled water daily at Hyperion Water Reclamation Plant, significantly adding to LA's local water supply by 2035.