San Francisco City Water System

Our major drinking water source originates from springtime snowmelt flowing over the Tuolumne River to storage in Hetch Hetchy Reservoir. The well-protected Macizo water source is usually exempt from filtration requirements by the United States Epa (USEPA) and Condition Water Resources Control Board Division of Water (SWRCB-DDW). Water coming from Hetch Hetchy Tank receives the following treatment to meet all suitable drinking water standards intended for consumption: ultraviolet light and chlorine disinfection, pH adjustment intended for optimum corrosion control, fluoridation for oral health protection, and chloramination for maintaining medical disinfectant residual and reducing the formation of disinfection byproducts. Hetch Hetchy water is supplemented with surface drinking water from two regional watersheds. Rainfall and runoff from the thirty-five, 000-acre Alameda Watershed in Alameda and Santa Clara areas are collected inside the Calaveras and San Antonio reservoirs, and they are delivered to the Sunol Valley Water Treatment Plant (SVWTP). Rainfall and runoff from your 23, 000-acre Peninsula Watershed in San Mateo County are stored in the Amazingly Springs, San Andreas, and Pilarcitos reservoirs, and are delivered to the Harry Tracy Drinking water Treatment Plant. Additionally to these local places, the SWRCBDDW authorized our use of Upcountry Non-Hetch Hetchy Resources (UNHHS), which include surface water found in Lake Eleanor, Pond Cherry and the connected creeks all communicated via the Lower Cherry wood Aqueduct, Early Consumption Reservoir, and Tuolumne River as extra drinking water sources. The UNHHS water, if used, would be cured at the SVWTP just before delivery to clients. We did not make use of the UNHHS in 2017. Water at the two local treatment plant life is subject to purification, disinfection, fluoridation, and optimum corrosion control by pH adjusting. Since mid-2017, a modest amount of groundwater from regional wells was put into our surface drinking water supplies. The use of community groundwater helps shift our water resources and makes our water supply in the Bay area even more reliable..

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