By John — Desalination News
Construction has formally begun on the long-delayed Rosarito seawater desalination plant in Baja California, Mexico, after years of stalled timelines and shifting contractors. Spanish infrastructure firm Cox broke ground on the project on September 25 in Playas de Rosarito, just south of Tijuana, with Mexico’s national water commission, Conagua, overseeing the award.
The first phase of the plant is designed to produce roughly 190 million liters of drinking water a day, enough to serve about one million people across Rosarito and southwest Tijuana. If the project proceeds to its full planned build-out, capacity would rise above 380,000 cubic meters daily, serving close to two million people in one of Mexico’s fastest-growing and most water-stressed border regions. Construction of the first phase is expected to take roughly three years, pointing to realistic delivery around 2029.
Cox, which absorbed Iberdrola Mexico’s energy assets, was awarded the roughly $304 million construction contract in August, following a selection process marked by repeated setbacks. The project was formally “confirmed” by Baja California officials as far back as March 2025, but stalled multiple times amid financing and contracting delays before Cox’s selection moved it forward. By the time construction started this week, the state had already spent an estimated 1.6 billion pesos on pre-construction work alone, a reminder of how costly and protracted large desalination projects can become even before a shovel goes into the ground.
The plant is intended to ease chronic water stress in a region that depends heavily on the Colorado River and increasingly strained aquifers, and where rapid population growth and industrial development, including a growing cluster of manufacturing tied to nearshoring investment, have pushed water demand well beyond what existing sources can reliably provide. Desalination has become a central pillar of Baja California’s water strategy as a result, alongside wastewater reuse and aquifer management programs.
Once complete, the Rosarito plant would add significant new capacity to a part of Mexico that has watched similar projects elsewhere in the country move from announcement to construction at very different speeds. The project’s binational context is also notable: Rosarito sits just across the border from San Diego County, and earlier proposals for cross-border water deals involving a Rosarito desalination plant have circulated for years as a possible way to help ease supply pressures on both sides of the border, although the current project is being built, financed, and operated as a Mexican domestic water-supply facility under Conagua’s authority.
The project adds to a broader wave of desalination investment across Latin America’s Pacific coast, where Chile and Peru have also turned to seawater plants to cope with drought and mining-driven water demand. For Baja California, the Rosarito groundbreaking represents a tangible, if overdue, step toward diversifying a water supply that officials have warned for years is increasingly unable to keep pace with the region’s growth.
With construction now underway, the next milestones to watch will be whether Cox can hold to the roughly three-year build timeline, and whether the broader, nearly two-million-person full build-out phase follows on a similarly protracted path to the one that delayed phase one for the better part of two years before this month’s groundbreaking.
(Source: Gringo Gazette North)