San Diego—In a bold and forward-thinking move, the city of San Diego is poised to revolutionize its water infrastructure by embracing a cutting-edge purification method that could dramatically alter the course of the acclaimed Pure Water San Diego initiative. With water security at the forefront of regional priorities, this development not only underscores the city’s leadership in sustainable urban utilities but also promises genuine savings, operational efficiencies and enhanced resilience.
Until now, the Pure Water program’s second phase—previously conceived as nearly double the scale of Phase One—was expected to incur sizable investment and widespread infrastructure expansion. However, owing to recent regulatory shifts and evolving demand dynamics, officials are now exploring the transformative potential of the advanced purification method known as direct potable reuse (DPR). Critically, this innovation may enable San Diego to bypass the construction of major pipelines to reservoirs such as San Vicente Reservoir or Lake Murray—thereby reducing both cost and complexity while accelerating local water independence.
As background, Pure Water San Diego is an ambitious multi-year program designed to supply nearly half of the city’s water locally by the end of 2035, leveraging recycled-water purification to produce safe, high-quality drinking water from treated wastewater. With Phase One nearing completion and delivering tens of millions of gallons per day, attention has now turned to Phase Two—originally projected at around 83 million gallons per day (mgd) combined with Phase One. Yet, in light of evolving demands, construction cost escalation and regulatory flexibility, city leadership is recalibrating the roadmap.
Crucially, the State of California recently eased its purification regulations to allow purified wastewater to be directly injected into the potable water system—eliminating the predetermined storage period in reservoirs or underground basins that had long been standard. This regulatory pivot empowers San Diego to adopt the DPR approach, unlocking a new tier of efficiency. City officials believe this innovative method could enable the city to build a smaller, leaner Phase Two—and avoid the daunting cost projections tied to the larger original design.
“We are at the forefront in the state on this,” explains Ally Berenter, Deputy Director of External Affairs for the city’s Public Utilities Department. “We’re very proud to be that kind of leader.” Her comment reflects San Diego’s ambition to be a model for water-reuse innovation.
Naturally, the transition to DPR comes with considerations. For example, water demand in San Diego is highly seasonal—low in winter, high in summer—which means the city cannot simply pump 100 percent of purified wastewater into the water system year-round. During off-peak periods, storage solutions may still be necessary. As Juan Guerrero, the city’s Public Utilities Director, succinctly states, “The one big reality that DPR ignores is the amount of water we’re delivering changes drastically throughout the year… you have to accommodate for some new investment in storage.”
Moreover, public acceptance remains a factor: the so-called “ick” factor that once accompanied the “toilet-to-tap” critique during earlier iterations of the project. Although Phase One utilized an indirect potable reuse method—including reservoir storage and interim natural interaction—the direct injection of purified water into the system via DPR removes that buffer, which may require enhanced community education. Officials remain true to the commitment of transparency and outreach. Berenter observes: “I think we’ve come a long way in terms of acceptance.”
That said, the benefits are noteworthy. By employing DPR, the city could significantly reduce the scale and cost of Phase Two, enabling a leaner infrastructure footprint and reducing long-term burdens on residents’ water and sewer bills. Current plans call for a purification plant on a 17-acre Mission Valley site adjacent to Snapdragon Stadium, followed by storage and distribution via major reservoirs; but with DPR in view, the consultant firm (Stantec) has been tasked with analyzing more than 20 alternative configurations and variables—ensuring any final design is optimized for cost, efficiency and community value.
In parallel, the wider Pure Water framework reveals strong strategic positioning. Should San Diego abandon or delay Phase Two as originally designed, the alternative—upgrading the aged Point Loma Wastewater Treatment Plant—would cost upward of $5 billion, while still leaving the city reliant on increasingly expensive imported water. Conversely, continuing with Phase Two under a DPR-enabled model is projected at around $4 billion, plus significant savings on imported supply and infrastructure over time.
Importantly, the ramifications of this pioneering strategy extend far beyond San Diego. The city serves as a regional hub—its sewer system supports customers in Chula Vista, El Cajon, La Mesa, Lemon Grove, National City, Coronado, Imperial Beach, Del Mar, Santee, Poway and parts of the unincorporated county, while its water system supplies San Diego, Coronado, Imperial Beach and Del Mar. The wholesale water authority has already projected steep rate increases (potentially 150 percent over the next decade) due to constraints on supply. Therefore, the success of DPR via the Pure Water program has the potential to deliver regional stability, economic relief and leadership in urban water resilience.
In closing, San Diego’s embrace of direct potable reuse marks a compelling chapter in the evolution of urban infrastructure—melding scientific innovation, regulatory agility and fiscal prudence. The city is not merely adapting to the future of water—it is actively shaping it. With Phase Two’s scope under thoughtful reevaluation and a path toward a smarter, leaner and more sustainable system in view, residents and stakeholders alike have cause for optimism. This initiative invites broader interest, investment and collaboration—and heralds a future where recycled water is not just a contingency, but a cornerstone of metropolitan sustainability.
For additional information about the Pure Water San Diego program, or to schedule a facility tour, please contact the City of San Diego Public Utilities Department.