(650) 727-6870 │ Mail: Clean Water Program, City of San Mateo, 330 W. 20th Avenue, San Mateo, CA 94403 info@cleanwaterprogramsanmateo.org


Protecting the Bay for a Sustainable Future


Have you ever wondered where used water (“wastewater”) goes after it leaves your home? Did you know that it eventually reaches the San Francisco Bay? It first travels through a series of sewer pipes and pumps called a sewer collection system and then gets treated at the Wastewater Treatment Plant before it is safe to flow into the Bay.

The Clean Water Program is a comprehensive plan to upgrade the aging wastewater collection and treatment system with advanced infrastructure that will provide reliable services for years to come. The Wastewater Treatment Plant components of the Clean Water Program are a joint effort between the City of San Mateo and City of Foster City/Estero Municipal Improvement District (EMID). The City of Foster City is a partial owner of the Wastewater Treatment Plant. The Goals of the Clean Water Program are to:


Replace aging infrastructure and facilities

Build wet weather sewer system capacity assurance to prevent overflows

Meet current and future regulatory requirements

Align with the City of San Mateo and Foster City's sustainability goals

Read Wastewater: The Basics to learn all about San Mateo’s sewer collection system and Wastewater Treatment Plant!



Latest Info


August 8, 2017, Study Session on the Wastewater Treatment Plant Upgrade and Expansion Project

The study session featured a presentation on the status of the planned upgrade and expansion of the treatment plant on a preliminary basis. The Clean Water Program is in the process of applying for a special use permit for this project from the City, and this session also provided an update on that permitting process.


City Council Selects Location for In-System Storage Facility

San Mateo’s existing wastewater system capacity is insufficient to address the wet weather flows that occur in the winter months and lead to sanitary sewer overflows (SSOs). To address this issue, a comprehensive approach to improve capacity involving an underground, in-system storage facility upstream of the WWTP is planned.

On July 17, 2017, the City Council selected the San Mateo County Event Center for the location of the underground storage facility. The Event Center is near where the most SSOs have historically occurred, near the intersection of S. Delaware Street and 25th Ave. Project. The northeast corner of the property, where the RV Storage Lot is located, will be used for the facility.

This storage facility will be capable of temporarily storing approximately 5 million gallons of wastewater during heavy rains. During these conditions, flows will divert from the sewer pipes to the storage facility to prevent overflows from occurring. After a storm subsides, and generally within 24 hours, wastewater in the facility will be pumped back into the collection system pipes and conveyed to the wastewater treatment plant.



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