Contractors across the U.S. are rapidly modernizing outdated wastewater infrastructure as utilities confront aging systems, climate stress and increased regulation around PFAS and other emerging contaminants. California’s latest milestone in that push comes with the completion of San Mateo’s $597 million wastewater treatment plant upgrade — the largest capital project in the city’s history.
Led by general contractor Sundt Construction, with Jacobs acting as project and construction manager and HDR serving as design engineer, the multiyear build replaces a system that had been operating for nearly 75 years. The overhaul eliminates recurring sewer overflows into neighborhoods and waterways while boosting operational efficiency and introducing advanced treatment technology.
Despite the massive scale of work, construction began in 2019 and crews successfully kept the existing plant functioning the entire time to maintain service for residents and businesses, according to the project team.
The upgraded plant is the flagship component of San Mateo’s $1 billion Clean Water Program, a long-term effort to strengthen sewer and stormwater performance throughout the region. Utilities officials say the improvements are critical to protecting the San Francisco Bay and keeping up with population growth and extreme weather.
Infrastructure enhancements include:
Officials say the new plant will not only handle peak stormwater loads but will also reduce energy use, improve odor control and protect sensitive Bay ecosystems.
San Mateo is just one of many communities accelerating investment in water infrastructure upgrades. The American Society of Civil Engineers gave U.S. wastewater systems a “D+” on its 2025 Infrastructure Report Card, pointing to deferred maintenance, increased flood risk and the rising cost of treating contaminants.
Industry analysts say that score reflects a multibillion-dollar pipeline of work ahead — especially for firms that have developed deep experience in water treatment technology.
Jacobs, which oversaw project delivery in San Mateo, has called water and wastewater construction a long-cycle growth engine in its recent earnings remarks, noting a surge in major program management contracts across the country. The company is also advancing major projects in Cincinnati and throughout Texas as utilities plan next-generation upgrades.
With the San Mateo treatment plant now online, regional officials say the investment will deliver environmental and public health benefits for decades to come. Additional phases of the Clean Water Program will continue to address collection system upgrades and improve resilience across the Bay shoreline.
Originally reported by Sebastian Obando in Construction Dive.
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