The Westborough Water District provides its customers with high quality drinking water that is safe to drink and meets standards set by the California Department of Health Services and the United States Environmental Protection Agency.
The Westborough Water District receives 100 percent of its water from the San Francisco Water Department. The water comes from Hetch Hetchy in Yosemite National Park and local reservoirs.
The California Department of Health Services and the United States Environmental Protection Agency set standards for drinking water quality.
The District collects samples throughout the system weekly to be analyzed for coliform bacteria, chlorine residual, pH, and turbidity. Every three months the District collect samples to monitor for trihalomethanes, or THMs, compounds formed when the chlorine used for disinfection reacts with naturally occurring organic compounds found in water. Water quality is monitored daily at the Harry Tracy treatment plant by the San Francisco Water Department.
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Please submit a request through the Contact Us page or call 650-589-1435.
Water Quality Reports
- 2021 Water Quality Report (PDF)
- 2020 Water Quality Report (PDF)
- 2019 Water Quality Report (PDF)
- 2018 Water Quality Report (PDF)
- 2017 Water Quality Report (PDF)
- Fluoride Information (PDF)
- Chloramine Information (PDF)
- Per- and Polyfluoroalkyl Substances (PFAS) Information (PDF)
Our Drinking Water Sources and Treatment
The Westborough Water District purchases 100% of its water from the San Francisco Public Utility Commission (SFPUC). The water supplied by the San Francisco Regional Water System (SFRWS), which is owned and operated by the SFPUC, our major water source originates from Spring Yosemite National Park snowmelt flowing down the Tuolumne River to storage in Hetch Hetchy Reservoir. The supply consists of surface water and groundwater that are well protected and carefully managed by the SFPUC. These sources are diverse in both the origin and the location with the surface water stored in reservoirs located in the Sierra Nevada, Alameda County and San Mateo County, and groundwater stored in a deep aquifer located in the northern part of San Mateo County. Maintaining this variety of sources is an important component of the SFPUC’s near- and long-term water supply management strategy.
To meet drinking water standards for consumption, all surface water supplies including the upcountry non-Hetch Hetchy sources (UNHHS) undergo treatment by the SFRWS before it is delivered. Water from Hetch Hetchy Reservoir is exempt from Federal and State filtration requirements but receives the following treatment: disinfection using ultraviolet light and chlorine, pH adjustment for optimum corrosion control, fluoridation for dental health protection, and chloramination for maintaining disinfectant residual and minimizing the formation of regulated disinfection byproducts. Water from local Bay Area reservoirs in Alameda County and UNHHS is delivered to Sunol Valley Water Treatment Plant (SVWTP); whereas water from local reservoirs in San Mateo County is delivered to Harry Tracy Water Treatment Plant (HTWTP). Water treatment at these plants consists of filtration, disinfection, fluoridation, optimum corrosion control, and taste and odor removal.
In 2021, no UNHHS water was used. However, a small amount of groundwater from four wells was added to the SFRWS’s surface water supply through blending in the transmission pipelines.
The SFRWS conducts watershed sanitary surveys for the Hetch Hetchy source annually and for non-Hetch Hetchy surface water sources every five years. The latest sanitary surveys for the non-Hetch Hetchy watersheds were completed in 2021 for the period of 2016-2020. All these surveys, together with SFRWS’s stringent watershed protection management activities, were completed with support from partner agencies including National Park Service and US Forest Service. The purposes of the surveys are to evaluate the sanitary conditions and water quality of the watersheds and to review results of watershed management activities conducted in the preceding years. Wildfire, wildlife, livestock, and human activities continue to be the potential contamination sources. You may contact the San Francisco District office of the State Water Resources Control Board’s Division of Drinking Water (SWRCB) at 510-620-3474 for the review of these reports.
Special Health Needs
Some people may be more vulnerable to contaminants in drinking water than the general population. Immuno-compromised persons, such as those with cancer undergoing chemotherapy, persons who have undergone organ transplants, people with HIV/AIDS or other immune system disorders, some elderly people and infants, can be particularly at risk from infections.
Monitoring of Per- and Polyfluoroalkyl Substances (PFAS)
PFAS is a group of approximately 5,000 man-made, persistent chemicals used in a variety of industries and consumer products. In 2021, our wholesaler conducted a second round of voluntary monitoring using a newer analytical method adopted by the USEPA for some other PFAS contaminants. No PFAS were detected above the SWRCB’s Consumer Confidence Report Detection Levels in surface water and groundwater sources. For additional information about PFAS, you may visit SWRCB website waterboards.ca.gov/pfas, SFPUC website sfpuc.org/tapwater, and/or USEPA website epa.gov/pfas
State Revised Total Coliform Rule
This report reflects changes in drinking water regulatory requirements during 2021, in which the SWRCB adopted California version of the Federal Revised Total Coliform Rule. The revised rule, effective on July 1, 2021, maintains the purpose to protect public health by ensuring the integrity of the drinking water distribution system and monitoring for the presence of microbials (i.e., total coliform and E. coli bacteria). Greater public health protection is anticipated, as the revised rule requires water systems that are vulnerable to microbial contamination to identify and fix problems. Water systems that exceed a specified frequency of total coliform occurrences are required to conduct an assessment to determine if any sanitary defects exist. If found, these must be corrected by the water system.
Groundwater Storage and Recovery (GSR) Project
Groundwater is a renewable source of naturally occurring fresh water that is found in underground and is replenished primarily by rainfall. The use of groundwater helps diversify water sources and makes drinking water supply even more reliable. The SFRWS completed installation of eight deep-water wells in its GSR project Phase 1. In 2021, some of these wells intermittently delivered water during the startup test to blend with the surface water supply in the north San Mateo County. For the past decade, the SFRWS has collected water quality and quantity data from the Westside Basin aquifer, from which the groundwater is extracted. With extensive monitoring and testing, the SFRWS knows that after adding groundwater to its water supplies, it will continue providing us with high-quality drinking water that meets or exceeds the Federal and State regulatory health-based and aesthetic standards.
Fluoridation and Dental Fluorosis
Mandated by State law, water fluoridation is a widely accepted practice proven safe and effective for preventing and controlling tooth decay. Our fluoride target level in the water is 0.7 milligram per liter (mg/L, or part per million, ppm), consistent with the May 2015 State regulatory guidance on optimal fluoride level. Infants fed formula mixed with water containing fluoride at this level may still have a chance of developing tiny white lines or streaks in their teeth. These marks are referred to as mild to very mild fluorosis, and are often only visible under a microscope. Even in cases where the marks are visible, they do not pose any health risk. The Centers of Disease Control (CDC) considers it safe to use optimally fluoridated water for preparing infant formula. To lessen this chance of dental fluorosis, you may choose to use low-fluoride bottled water to prepare infant formula. Nevertheless, children may still develop dental fluorosis due to fluoride intake from other sources such as food, tooth paste and dental products.
Drinking Water and Lead
Exposure to lead, if present, can cause serious health effects in all age groups, especially for pregnant women and young children. Infants and children who drink water containing lead could have decreases in IQ and attention span and increases in learning and behavior problems. The children of women who are exposed to lead before or during pregnancy can have increased risk of these adverse health effects. Adults can have increased risks of heart disease, high blood pressure, kidney, or nervous system problems.
Lead User Service Line (LUSL)
Lead Testing of Drinking Water in Schools
Lead and Copper Tap Sampling Results
Urban Water Management Report
In compliance with the Urban Water Management Planning Act, the Westborough Water District (WWD.) has prepared its sixth updated Urban Water Management Plan (UWMP) under the terms of AB797 (1983) and subsequent amending legislation.
On June 10, 2021, this plan was presented at a Public Hearing and approved by the WWD Board of Directors. It supercedes the existing plan prepared in 2015, and will be used by the District staff to guide the District's water conservation efforts through the year 2025.