San Francisco has a combined sewer system that collects sewage and stormwater in the same network of pipes, which is then pumped, treated, and discharged to the San Francisco Bay and Pacific Ocean. In most cities, street storm drains flow directly out into creeks, lakes or oceans. While several cities around the country have combined sewers, including Boston, New York and Philadelphia, San Francisco is one of only two in California. Cleaning stormwater is just as important as sewage because of the car oil, metals and litter that wash into the sewers from streets. Imagine the impact on the fish and wildlife in the bay and ocean if we didn’t treat these street pollutants.

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The storage/transports are huge underground rectangular tanks or tunnels that ring the City like a moat. During rainstorms, the storage/transports prevent untreated shoreline discharges. The storage/transports have three functions:     Read more 

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Wastewater flows from the east side of the City are transported to the Southeast Wastewater Treatment Plant through the Bayside Transport System. During wet weather, the combined sewerage system collects large volumes of stormwater runoff in addition to municipal and industrial wastewater, and the combined flow is conveyed to treatment facilities before eventual discharge to the Bay.     Read more 

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The storm water runoff mixed with domestic and industrial wastewater from the City’s west drainage area is collected in the Westside Wet Weather Facilities. The Westside system includes three large storage/transports: Westside Transport, Richmond Transport, and Lake Merced Transport.     Read more 

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