City of San José
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68℉The Source of Your Water
The San José Municipal Water System (Muni Water) serves the North San José, Alviso, Evergreen, Edenvale and Coyote Valley communities of the City of San José. The source of your water depends on the service area in which you are located.
North San JosE/Alviso Service Area
Muni Water purchases a blend of Hetch Hetchy water and treated water from the San Francisco Public Utilities Commission (SFPUC) and delivers it to our Alviso and North San José customers. In 2023, the Hetch Hetchy Watershed provided most of the total SFPUC water supply, supplemented by local watersheds in Alameda and Santa Clara counties. The major water source originates from spring snowmelt flowing down the Tuolumne River to the Hetch Hetchy Reservoir, where it is stored. Since this water source meets all federal and state criteria for watershed protection, disinfection treatment practices, bacteriological quality monitoring, and high operational standards, the EPA and state of California have granted this water source a filtration exemption.
The Alameda Watershed spans more than 35,000 acres in Alameda and Santa Clara counties. Surface water from rainfall and runoff is collected in the Calaveras and San Antonio reservoirs. Prior to distribution, the water from these reservoirs is treated at the Sunol Valley Water Treatment Plant (SVWTP). Filtration, disinfection, fluoridation, and corrosion control treatment are provided for the combined Hetch Hetchy and SVWTP water at the Sunol Chloramination and Fluoridation facilities.
The SFPUC actively and aggressively protects the natural water resources entrusted to its care. An annual report on the Hetch Hetchy Watershed reflects the evaluation of its sanitary conditions, water quality and potential contamination sources. The report also presents performance results of watershed management activities implemented by the SFPUC and partner agencies to reduce or eliminate potential contamination sources. The SFPUC also conducts sanitary surveys of the local watersheds every five years. These surveys identified wildlife, livestock, and human activities as potential contamination sources. You may contact the San Francisco office of the State Water Resources Control Board’s Division of Drinking Water at 510-620-3474 for review of these reports.
In 2023, groundwater from local deep-water wells in North San José was utilized to supplement the SFPUC supply. With this additional water source, some customers may have received a blend of groundwater and SFPUC water. A slight difference in taste and odor may have been noticed since groundwater generally has a higher mineral content than surface water.
Muni Water conducted a one-time source water assessment of the wells in January 2003.*
Evergreen Service Area
Muni Water purchases treated surface water from Valley Water (formerly known as the Santa Clara Valley Water District) and delivers it to our Evergreen customers. Valley Water’s surface water is mainly imported from the South Bay Aqueduct, Dyer Reservoir, Lake Del Valle and San Luis Reservoir, which all draw water from the Sacramento-San Joaquin Delta watershed. Valley Water local surface water sources include Anderson and Calero reservoirs. Water from imported and local sources is pumped to and treated at three water treatment plants located in San José.
Since 2006, Valley Water has used ozone as the primary disinfectant. Ozone disinfection is highly effective at inactivating microbial contaminants and creates fewer disinfection by-products than chlorine. Ozone also effectively removes negative tastes and odors often caused by seasonal algal blooms in the Delta source waters.
Valley Water’s source waters are vulnerable to potential contamination from a variety of land use practices, such as agricultural and urban runoff, recreational activities, livestock grazing, and residential and industrial development. Imported sources are additionally vulnerable to wastewater treatment plant discharges, seawater intrusion, and wildfires in open space areas. Local sources are additionally vulnerable to contamination from commercial stables and historic mining practices. No contaminant associated with any of these activities has been detected in Valley Water’s treated water. The water treatment plants provide multiple barriers for physical removal and disinfection of contaminants. For additional information, visit the Valley Water website at www.ValleyWater.org.
During 2023, Muni Water utilized groundwater from local deep-water wells to supplement Valley Water’s supply. Some customers may have received a blend of groundwater and Valley Water’s treated water. A slight difference in taste and odor may have been noticed since groundwater generally has a higher mineral content than surface water. Muni Water conducted a source water assessment for the Evergreen wells in December 2014.*
Edenvale Service Area
Groundwater from deep-water wells provides 100 percent of the supply for the Edenvale service area. Muni Water conducted a one-time source water assessment for the Edenvale wells in January 2003.* Although the source is considered potentially vulnerable to chemical and petroleum processing activities, no contaminants associated with these activities have been detected.
Coyote Valley Service Area
Groundwater from deep-water wells provides 100 percent of the supply for this service area. An assessment of these wells was conducted in June 2004,* and potable use of the groundwater began in 2005. Although the source is considered potentially vulnerable to agricultural drainage, unauthorized dumping, storage tank leaks, and sewer collection systems, no contaminants associated with these activities have been detected.
* For information about the type of contaminants tested or to get a copy of the groundwater well assessment reports for your service area, please contact a Water Quality Engineer at 408-277-3671.