Water Quality

PHWD Water Quality

The San Francisco Regional Water System (SFRWS) regularly tests water from reservoirs and designated sampling locations throughout the system. In 2025, the SFRWS performed more than 45,550 drinking water tests of samples from source and transmission system locations and PHWD conducted 205 drinking water tests of samples from our specific system. This is in addition to the extensive treatment process monitoring conducted by the certified operators and online instruments.

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. 

---

Annual Water Quality Reports

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

• 2025 Consumer Confidence Report (PDF)
• 2024 Consumer Confidence Report (PDF)
• 2023 Consumer Confidence Report (PDF)
• 2022 Consumer Confidence Report (PDF)
• 2021 Consumer Confidence Report (PDF)
• 2020 Consumer Confidence Report (PDF)
• 2019 Consumer Confidence Report (Available Soon)
• 2018 Consumer Confidence Report (PDF)
• 2017 Consumer Confidence Report (PDF)
• 2016 Consumer Confidence Report (PDF)
• 2015 Consumer Confidence Report (PDF)

---

Our Drinking Water Sources and Treatment

Our surface water is stored in reservoirs in the Sierra Nevada, Alameda County, and San Mateo County. Maintaining these sources is an important component of our near- and long-term water supply management strategy of the San Francisco Public Utilities Commission (SFPUC). A diversity of sources not only protects us from potential disruptions due to emergencies or natural disasters, but also provides resiliency during periods of drought. It helps us ensure a 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 approved by the regulatory agencies. Water from Hetch Hetchy Reservoir is exempt from state and federal filtration requirements due to its exceptional quality. However, it is still subject to 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 reservoirs in Alameda County and upcountry non-Hetch Hetchy sources are delivered to the Sunol Valley Water Treatment Plant.

In 2025, neither the SFRWS’s upcountry non-Hetch Hetchy sources nor its groundwater wells were used; however, the SFRWS imported a very small amount (0.38%) of treated water from Valley Water District in April and May. 

---

Notification of Process Monitoring Violation

This notice is to inform you that the SFRWS failed to monitor for recycled filter backwash water turbidity at its Sunol Valley Water Treatment Plant from June 23, 2025 to July 2, 2025. This monitoring violation was the result of equipment failure and was corrected on July 3, 2025 as soon as it became apparent to plant staff. This failure was not an emergency and did not impact water quality.

DOWNLOAD NOTIFICATION (PDF)

---

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 its Hetch Hetchy source annually and the non-Hetch Hetchy surface water sources every five years. The latest sanitary surveys for the non-Hetch Hetchy watersheds were completed in 2021. These surveys summarize the following:

• Sanitary conditions of the watersheds n Water quality of the reservoirs in the watersheds
• The SFRWS’s stringent watershed protection activities that are implemented with support from its partner agencies including the National Park Service and the United States Forest Service
• Results of watershed management activities conducted in prior years

Overall wildlife, livestock, human activities, and wildfire 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.

---

Special Health Needs

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.

The SFRWS regularly tests for Cryptosporidium, a waterborne parasitic microbe that may be spread through means other than drinking water. As in the past, this pathogen was found at very low levels in source water and treated water in 2025. Current test methods approved by the United States Environmental Protection Agency (USEPA) do not distinguish between dead organisms and those capable of causing disease. Cryptosporidium must be ingested to cause cryptosporidiosis with symptoms of nausea, abdominal cramps, diarrhea, and associated headaches.

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

---

Drinking Water and Lead

Lead can cause serious health problems, especially for pregnant women and young children. Lead in drinking water is primarily from materials and components associated with service lines and home plumbing. PHWD is responsible for providing high quality drinking water and removing lead pipes, but cannot control the variety of materials used in plumbing components in your home. You share the responsibility for protecting yourself and your family from the lead in your home plumbing. You can take responsibility by identifying and removing lead materials within your home plumbing and taking steps to reduce your family’s risk. Before drinking tap water, flush your pipes for several minutes by running your tap, taking a shower, doing laundry or a load of dishes. You can also use a filter certified by an American National Standards Institute accredited certifier to reduce lead in drinking water. Information on lead in drinking water, testing methods, and steps you can take to minimize exposure is available at epa.gov/safewater/lead

---

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.