PHWD Water Quality

Together with the SFRWS, the PHWD regularly collects and tests water samples from reservoirs and designated sampling locations throughout its system to ensure the water delivered to you meets all state and federal drinking water standards. In 2024, the SFRWS conducted more than 45,650 drinking water tests of samples from source and transmission system locations and PHWD conducted 199 drinking water tests of samples from our specific system. This is in addition to the extensive treatment process control monitoring performed by our certified operators and online instruments.

Photo of the Hetch Hetchy reservoir


As water travels over the surface of the land or through the ground it dissolves naturally occurring minerals and, in some cases, radioactive material, and can pick up substances resulting from the presence of animals or human activity. Collectively these are called contaminants. Therefore, drinking water, including bottled water, may reasonably be expected to contain at least small amounts of some contaminants. The presence of contaminants does not necessarily indicate that water poses a health risk. To ensure that tap water is safe to drink, the United States Environmental Protection Agency (USEPA) and the State Water Resources Control Board (SWRCB) prescribe regulations that limit the amount of certain contaminants in water provided by public water systems. The United States Food and Drug Administration regulations and California law also establish limits for contaminants in bottled water that provide the same protection for public health.

banner image for downloading the PHWD 2024 Annual Water Quality Report


Annual Water Quality Reports

Water quality results are published annually in the PHWD Consumer Confidence Reports (CCRs).

Our Drinking Water Sources and Treatment

Our drinking water supply consists of surface water and groundwater that are well protected and carefully managed. The surface water is stored in reservoirs in the Sierra Nevada, Alameda County, and San Mateo County and the groundwater is kept in a deep aquifer in the northern part of San Mateo County. Maintaining this variety of sources is an important component of the near- and long-term water supply management strategy of the San Francisco Public Utilities Commission (SFPUC). A diverse mix of sources protects us from potential disruptions due to emergencies or natural disasters, provides resilience during periods of drought, and helps us ensure a long-term, sustainable water supply as we address issues such as climate uncertainty, regulatory changes, and population growth. 

To meet drinking water standards for human consumption, all surface water the SFPUC supplies must undergo proper treatment. Water from Hetch Hetchy Reservoir is exempt from state and federal filtration requirements due to its exceptional quality. It undergoes 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 upcountry non-Hetch Hetchy sources are delivered to the Sunol Valley Water Treatment Plant. In 2024, neither upcountry non-Hetch Hetchy sources of water nor groundwater was used. 

Image of the Hetch Hetchy regional water system

Taste, Odor, or Discolored Water Issue?

Opening a faucet or two in your home or business, or an outside spigot, to let the water run for a couple of minutes should resolve it. Remember to capture the water in a bucket to use for watering indoor plants or outdoor landscaping!

Depending upon the water turnover in the mainline serving your connection, or seasonal fluctuations in water treatment by San Francisco Water, a temporary water quality issue could be quickly resolved with a mini-flushing of your service line.

You can now use PHWD's Online Water Quality Self-Diagnosis Tool to help determine possible causes and solutions of typical water quality issues experienced in a home. If the problem persists, please contact us at 650-948-1217 or online here.

Protection of Watersheds

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. 

These surveys document the San Francisco Public Utility Commission’s (SFPUC) stringent watershed protection activities that are implemented with support from partner agencies including the National Park Service and the United States Forest Service. These surveys not only evaluate the sanitary conditions and water quality of the watersheds but also describe the 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 SWRCB Division of Drinking Water at 510-620-3474 for more information.

Image of the Tuolumne River and Hetch Hetchy watershed


Special Health Needs

Image of two adolescents with glasses of water

Some people may be more vulnerable to contaminants in drinking water than the general population. Immunocompromised persons, such as those with cancer undergoing chemotherapy, persons who have undergone organ transplants, people with Human Immunodeficiency Virus/Acquired Immunodeficiency Syndrome or other immune system disorders, some elderly, and infants can be particularly at risk from infections. These people should seek advice about drinking water from their healthcare providers.

Cryptosporidium is a parasitic microbe found in surface water. We regularly test for this waterborne pathogen and found it at very low levels in source water and treated water in 2024. Cryptosporidium must be ingested to cause disease, and it may be spread through means other than drinking water. 

Guidelines on appropriate means to lessen the risk of infection by Cryptosporidium and other microbial contaminants are available from the USEPA’s Safe Drinking Water Hotline at 800-426-4791 or at epa.gov/safewater.

Boron Detection Above Notification Level in Source Water

In 2024, boron was detected at a level of 2.3 parts per million (ppm) in the raw water stored in Pond F3 East, one of the SFRWS approved sources in the Alameda Watershed. Similar levels were detected in the same pond in preceding years. Although the detected value was above the California Notification Level of 1 ppm, the water was typically delivered to San Antonio Reservoir where it was substantially diluted to below the Notification Level before treatment at the Sunol Valley Water Treatment Plant. Boron is an element in nature and is typically released into air and water when soils and rocks naturally weather.

No PFAS Detected

Per- and poly-fluoroalkyl substances (PFAS) comprise a group of man-made, persistent chemicals that have been used in the industry and consumer products since the 1940s. We did not detect PFAS in our water. To learn more, visit waterboards.ca.gov/pfas.

Fluoridation

The SFRWS adds fluoride to our water. California law mandates fluoridation. It is proven safe. It is also effective at preventing and controlling tooth decay. Our fluoride levels match the state’s optimal level. To learn more, visit cdc.gov/fluoridation or sfpuc.gov/TapWater

Lead and Drinking Water

Exposure to lead, if present, can cause serious health effects in people of all ages, especially for pregnant women and young children. Infants and children who drink water containing lead could have decreases in intelligent quotient and attention span as well as increases in learning and behavior problems. The children of women who are exposed to lead before or during pregnancy can have an increased risk of these adverse health effects. Adults can have increased risks of heart disease, high blood pressure, kidney, or nervous system problems. 

Lead in drinking water is primarily from materials and components associated with service lines and home plumbing. We are responsible for providing high-quality drinking water and removing lead pipes, but we cannot control the variety of materials used in plumbing components in your home. Because lead levels may vary over time, lead exposure is possible even when your tap sample results do not detect lead at one point in time. You share the responsibility for protecting yourself and your family from the lead in your home plumbing by taking one or more of the following actions:

  • Identify and remove lead materials within your home plumbing.
  • If you use a water filter, make sure it’s certified for lead to National Sanitation Foundation (NSF)/ANSI standards. Make sure to replace and maintain the filter according to the manufacturer’s instructions. 
  • Use only cold water for drinking, cooking, and making baby formula (Do not boil your water to remove lead. Boiling water will not remove lead).
  • Flush your pipes for several minutes before using your water for drinking, cooking, and preparing baby formula (this can be done by running your tap, taking a shower, doing laundry or a load of dishes, or reusing for watering plants). 
  • Flush for a longer period if you have pipes made of lead or galvanized material. Visit sfpuc.gov/lead to see an instructional video if you would like to test your pipes.

If you are concerned about lead in your water, you can have your water tested. Information about lead in drinking water, testing methods, and steps you can take to minimize exposure is available at epa.gov/safewater/lead.

Unregulated Contaminant Monitoring Rule

The SFRWS conducted four consecutive quarters of monitoring at designated locations approved by the United States Environmental Protection Agency in 2024, and all results have been non-detected.

Lead and Copper Inventory Compliance

PHWD completed the Lead and Copper Rule Revisions (LCRR) service line inventory on October 1, 2024. The EPA requires water systems to create and maintain a service line inventory of their materials. These results are accessible in the interactive tool found below. If you have questions about the results of the LCRR service line inventory at your address, please contact the PHWD online here or call 650-948-1217. 

Check Your LCRR Service Line Inventory Results

Enter your address below to see the results.

system and customer-owned service lines illustration

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