City of Milpitas

Milpitas obtains water from two primary sources to deliver clean water to residents and businesses. The city purchases water from two separate wholesale suppliers: treated surface water from the San Francisco Public Utility Commission (SFPUC) and treated surface water from the Santa Clara Valley Water District (SCVWD).

In emergency situations when water supply from either SCVWD or SFPUC is disrupted, the city can utilize its backup supply to meet essential water needs temporarily. During 2017, Milpitas distributed approximately 6.8 million gallons of water daily to roughly 16,000 homes and businesses for both indoor and outdoor usage.

SFPUC Water Supply

SFPUC water consists of a blend of Hetch Hetchy water and treated local water. The majority of SFPUC's water comes from the Hetch Hetchy watershed in the Sierra Nevada Mountains. This particular water source is exempt from filtration requirements by both the United States Environmental Protection Agency (USEPA) and State Water Resources Control Board's Division of Water (DDW), thanks to the protected Sierra spring snowmelt source. Local water is collected within the Alameda watershed at Calaveras Reservoir and San Antonio Reservoir, then treated through filtration and disinfection at the Sunol Valley Water Treatment Plant.

SCVWD Water Source

SCVWD water primarily originates from the Sacramento-San Joaquin Delta watershed via the South Bay Aqueduct, Dyer Reservoir, Lake Del Valle, and San Luis Reservoir. This supply is supplemented by local water sources at Anderson and Calero Reservoirs. SCVWD water undergoes treatment through filtration and disinfection at Penitencia and Santa Teresa Water Treatment Plants.

Emergency Water Supplies

Under normal operating conditions, the City does not mix SFPUC and SCVWD waters. However, service areas can be interconnected to provide emergency water if necessary. Milpitas' water system also connects with the Alameda County Water District to the north and San Jose Water Company to the south. In emergencies, either or both agencies can supply water to the City. SFPUC and SCVWD share an intertie that can supply water from one wholesaler to the other. Additionally, the City can provide short-term emergency water using Pinewood Well, located in the southwestern part of Milpitas.

Water Source Assessment Programs

These programs evaluate the vulnerability of water sources to potential contamination. Both SFPUC and SCVWD have conducted water source assessments for Milpitas' approved water supplies. These assessments are available for review at the State Water Resources Control Board (SWRCB) - Division of Drinking Water District Office by calling (510) 620-3474.

SFPUC performs annual watershed sanitary surveys for the Hetch Hetchy source and five-year sanitary surveys for local water resources. These surveys assess sanitary conditions, water quality, potential contaminant sources, and watershed management activities' results. The surveys were completed with assistance from partner organizations including the National Park Service and US Forest Service, identifying wildlife, livestock, and human activities as potential contamination sources.

SCVWD's water sources are vulnerable to potential contamination from various land-use practices, including agricultural and urban runoff, recreational activities, livestock grazing, and residential and commercial development. Imported sources are also vulnerable to wastewater treatment plant discharges, seawater intrusion, and wildfire in open spaces. Regional sources face additional risks from commercial stables and historic mining practices. However, no contaminants associated with these activities have been detected in SCVWD's treated water.

Water Safety Regulations

Water treatment plants provide multiple barriers for physical removal and disinfection of contaminants. To ensure tap water safety, the U.S. Environmental Protection Agency (USEPA) and the State Water Resources Control Board prescribe regulations limiting certain contaminants in public water systems. State Board regulations also establish contaminant limits for bottled water to provide similar public health protection.

Water sources (both tap and bottled) include rivers, lakes, streams, ponds, reservoirs, springs and wells. As water travels over land surfaces or through the ground, it dissolves naturally occurring minerals and sometimes radioactive material, and may pick up substances from animal presence or human activity.

Potential contaminants in source water include:

• Microbial contaminants such as viruses and bacteria from sewage treatment plants, septic systems, agricultural operations, and wildlife
• Inorganic contaminants like salts and metals, which can occur naturally or result from urban stormwater runoff, industrial/domestic wastewater discharges, oil/gas production, mining, or farming
• Pesticides and herbicides from various sources including agriculture, urban stormwater runoff, and residential uses
• Organic chemical contaminants, including synthetic and volatile organic chemicals from industrial processes, petroleum production, gas stations, urban runoff, agricultural applications, and septic systems
• Radioactive contaminants that occur naturally or result from oil/gas production and mining activities

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