San Francisco has a combined sewer system that collects sewage and storm water 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 storm water 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.
The Problem
San Francisco’s first 250 miles of sewers were built in the late 1800s and by 1935 almost two thirds of the system we have today had been installed. The normal life expectancy of sewers ranges from 50 to 100 years, so a large portion of our pipes have exceeded their expected lifespan.
Next: our treatment plants
