View the City of Palo Alto's Annual Water Quality Report(PDF, 14MB). Also available in Spanish(PDF, 694KB) and Traditional Chinese(PDF, 883KB).
Local Water Supply
Palo Alto’s water comes from the San Francisco Public Utilities Commission (SFPUC). This high quality water supply consists almost entirely of Sierra Nevada snowmelt delivered through the Hetch Hetchy water distribution system. Precipitation levels can vary greatly within any given year. Even though we may experience periods of wet weather, a warm dry spell can affect water supplies later in the year. These climate conditions, along with our limited long-term water supplies, mean it is in our best interest to use water as efficiently as possible, regardless of drought conditions. Learn more about the City of Palo Alto's Urban Water Management Plan.
Helpful Information about Your Water Supply
This new video from our friends at BAWSCA talks about our precious water supply & how membership in this agency has helped CPAU, among other member agencies, protect our high-quality water at a fair price.
Current Water Source Blend
The following table compares water quality parameters at Irvington Portal. This data is based on the most recent sampling results and represents an estimate of how the blend parameters will change.
|| As of Jan 13
||As of Jan 17
||As of Jan 24
| HH Flow (MGD)
|HTWTP Flow (MGD)
| SVWTP Flow (MGD)
| SFPUC-SCVWD Intertie (MGD)
| Total Chlorine Residual (mg/L)
| Free Ammonia-N (mg/L)
| Conductivity (uS/cm)
| Hardness (mg/L)
| Alkalinity (mg/L)
| TOC (mg/L)
Previous Palo Alto Annual Water Quality Reports
Recycled Water & Other Alternative Water Sources
- Recycled water is available from the Regional Water Quality Control Plant for use with construction activities and landscape irrigation.
- Read information on how to use Recycled Water here, including how to obtain the necessary permit.
- Interested in opportunities for reusing water that is "dewatered" or pumped from the ground during construction projects? Read our FAQs.
Water Distribution System Flushing
City staff need to periodically flush water mains and hydrants with fresh water to prevent the water quality from degrading. This is more frequently needed in areas where a cul-de-sac or end-of-the-line piping tend to accumulate vegetation, algae or sediment. Flushing is necessary to keep debris out of customers' service line. We post signs at each site to let people know that this is being done. We monitor our water quality every day to ensure that it meets all State and Federal guidelines for drinking water quality standards. If a customer experiences discoloration or sediment in water coming from the tap, they should flush the cold (not hot) water for a minute or more until the water clears.
Flushing Guidance for Buildings Following Shutdown
Businesses are returning to work after an extended shutdown due to COVID-19 public health shelter in place orders. If a building has been vacant and dormant, water use has been reduced, which could result in a degradation in water quality. Stagnant water can harbor bacteria, so it is important to flush your water system before you begin using the water again. Our water supplier has provided guidance with steps to take when restoring water service.
The City of Palo Alto takes its responsibility to protect customers from lead exposure very seriously. Palo Alto Utilities does not have lead services or other equipment in our system, though we still perform sampling to ensure clean, safe drinking water quality. The City of Palo Alto’s lead sampling technique uses best practices for accurate water quality testing. If you have questions about the City's lead or other water quality testing procedures, please contact our Water Transmission Staff at (650) 496-6967.
Chromium is an abundant element in the Earth’s crust, found naturally in rocks, plants, soil and volcanic dust, humans and animals. One form, hexavalent chromium, is widely found in waters, including source waters for drinking water, typically at VERY low concentration levels. Chromium 6 is not a concern in Palo Alto. The water supplies we receive from the SFPUC fully comply with the new California Chromium 6 MCL standard finalized in July 2014.