WITH MEXICO FINALLY BUILDING ITS BIG DESALINATION PLANT,
The possibility of sending water to the U.S. has surfaced again.

By Vicente Calderón. Water Canada Mexico bureau.

After years of delay, Rosarito's desalination plant finally has a builder. On August 14, 2026, Mexico's National Water Commission (CONAGUA) awarded the construction contract to Cox Energy, a Spanish firm bidding jointly with Cox Water, S.L., beating out proposals from Acciona and a consortium tied to Israel's IDE Water Mexico. The winning bid came in at 5.29 billion pesos, with a three-year construction window. The contract is set to be formalized by August 28.

The federal government will cover roughly 70% of the plant's cost, according to a North American Development Bank (NADBank) financing document, while Baja California will borrow up to 2 billion pesos from NADBank for the pipelines and tanks needed to move the water to Tijuana, Rosarito and Ensenada. 

But naming a winning bidder doesn't mean relief is coming anytime soon — and not everyone agrees it was the right first move. "Desalination here has always been an option, and it has to be part of the mix," said Jessica Castañeda, an engineer with Tijuana's Center for Innovation and Environmental Management (CIGA), who has tracked the project's stalled history for years. "But step one should have been fixing leaks." Other academics and water experts interviewed for this story agreed.

Tijuana's water utility loses roughly 1,000 liters per second to leaks — almost exactly half of what the new 2,200-liter-per-second plant will produce. "We could recover the same amount the plant will produce, just by patching pipes," Castañeda said.

She isn't opposed to the project; she just wants people to understand what it will and won't fix. Other researchers put Tijuana's leak rate at 20% to 30% — Castañeda leans toward the higher end — and as high as 45% in Ensenada. Water reuse, meanwhile, sits at just 4%. Without addressing either problem, she warns, the new desalinated water will flow straight into the same leaking network. "You'd be pumping treated water into a broken pipe," she said. "It's the same 20% you'd lose all over again. again." She expects meaningful relief if the plant stays on schedule, but only alongside leak repair and reuse. "It's not a simple problem with a simple fix. The state should be doing all of it at once."

The announcement comes amid another hot summer without enough water for the more than 2 million residents of this border metropolitan area — and just as Arizona looks to import water to address its own drought. 

The idea of selling desalinated water to the U.S. is not new and has long been mired in controversy. About a decade ago, a public-private contract to build a larger plant collapsed after Baja California signed a deal with Aguas de Rosarito, a subsidiary of the Cayman Islands-based Consolidated Water Co. Ltd. Protests erupted over the ghost of privatization and the prospect of shipping scarce Mexican water north, leading the government to terminate the contract in 2020. Consolidated Water sued through international arbitration, and the case dragged on until 2024, when Mexico agreed to pay roughly $36 million to settle the dispute and acquire the project's land and some studies and design plans. 

Later, the administration of Andrés Manuel López Obrador revived the project, and President Claudia Sheinbaum carried it forward. Now, it looks ready to break ground. The new plant's first module will produce 2,200 liters per second — exactly half the 4,400 lps originally planned. "That missing half was the portion meant for San Diego," said engineer Manuel Becerra Lizardi, who has spent more than 50 years of experience in the water, infrastructure and sanitation sector.

 "Once San Diego built its own plant in Carlsbad, that part of the project stopped being essential." Castañeda thinks the door to exporting surplus water hasn't closed. "I do believe that's eventually where this is headed," she said, though she isn't troubled by the prospect. "We're a binational region. Natural gas flows north, electricity flows north — I'm not against water doing the same." Her real objection to the 2016 deal wasn't exporting water, but a contract that paid a private operator regardless of whether the water was used. Becerra agrees, noting that dependence on the Colorado River aqueduct already complicates the notion of absolute sovereignty. 

Arizona, for its part, is moving cautiously. Two consortiums — Canada's EPCOR and Spain's Acciona — have pitched concepts to the Arizona Water Infrastructure Finance Authority (WIFA), including desalination plants in the Gulf of California. "Nothing is set in stone," said Ben Alteneder, WIFA's deputy director of external affairs. "It's very conceptual at this point." Any deal, he added, has to be a win-win for everyone.

That caution traces back to a 2023 diplomatic mess when an Israeli firm pitched WIFA an unsolicited $5.5 billion plant for Puerto Peñasco, Sonora, claiming permits it didn't have. Sonora Governor Alfonso Durazo called it "total nonsense," and his government announced it would never deal with that company again.

The urgency is measured daily. Baja California's coast depends almost entirely on the Colorado River, as local groundwater is depleted. Bureau of Reclamation records show Lake Mead fell to 1,039.31 feet by August 22 — below the symbolic 1,040-foot line — holding just 6.93 million of its 26.12-million-acre-foot capacity. On August 21, the Interior Department locked in a 1.25-million-acre-foot cut for Arizona, California and Nevada starting in 2027. Mexico's own reduction is still being negotiated through a separate binational channel. For Baja California, the contract award is a real milestone after a decade of false starts. But as Castañeda put it, the plant alone "won't fix Tijuana's water crisis." What it does open is the door to a steadier supply — and, eventually, perhaps, to selling water north.