Water Quality Updates

Water Quality Notice

WATER QUALITY CHANGES – December 3, 2024
Water will continue to meet all regulatory standards

The San Francisco Public Utilities Commission (SFPUC) plans to shut down supply deliveries from Hetch Hetchy Reservoir on December 3rd for approximately 102 days to accommodate maintenance and improvements.  Source water will be switched to local supplies that are treated with the Sunol Valley Water Treatment Plant (SVWTP).  These source water changes are part of normal seasonal supply management to accommodate capital improvements, maintenance, and upgrades to the Regional Water System.

The table below shows expected water quality, the changes below will affect Stanford approximately 24 hours after the date noted (average travel time from East Bay facilities to Stanford).

Expected Water Quality

CONSTITUENT	UNIT	SFPUC as of 11/19/24: Blend (Hetch Hetchy and SVWTP)	SFPUC as of 12/3/24: Blend (SVWTP)
Chlorine residual (total)	mg/L	3.3	3.3
Free Ammonia-N	mg/L	0.05	0.05
pH	pH	9.6	8.6
Turbidity	NTU	0.23	0.10
Conductivity	µS/cm	83	330
Hardness	mg/L	26	110
Alkalinity	mg/L	27	120
TOC	mg/L	1.6	2.2

What does the water quality change mean for equipment and processes in laboratories?

Equipment and processes in labs or academic buildings may be affected by fluctuations in hardness, alkalinity, and conductivity over the transition. 

If you have any questions or concerns, please contact water information line at 650-725-8030.

To be notified of domestic water quality blend changes in the future, sign up to receive automated emails from our drinking water quality list serve

Water Quality Background Information

During normal operations, 100% of the domestic water delivered to the Stanford campus comes from the San Francisco Public Utilities Commission (SFPUC). The water is delivered to Stanford University and has already been treated and disinfected with chloramine (the water is also fluoridated and the pH is adjusted for corrosion control). Stanford does not apply additional treatment to the water received from SFPUC.

The source water from SFPUC is typically from the Hetch Hetchy reservoir located in the Sierra Nevada Mountains. Occasionally the source water will shift to local reservoirs during routine maintenance to the conveyance system. During most years, there will be a 30-day shut down of the Hetch Hetchy source in the winter months. More information about this and any other anticipated water quality will be provided through this website and our water quality list serve ahead of planned operational changes.

In addition, sensitive water users on campus should be aware that in the event of an emergency or other operational need, on-campus groundwater wells would be used to supplement or replace the domestic water supply that typically comes from SFPUC. The groundwater from on campus groundwater wells will have significantly different water quality than what is typically received from SFPUC. If you have operations that are sensitive to changes in hardness, dissolved solids, and pH, you should plan for alternative operations during such a change to protect processes, equipment, and/or research. We will send notices through the water quality list serve if groundwater will be introduced into our drinking water distribution system.

Average Water Quality

Below is a summary of average water quality in various treated source waters. The reliability, safety, and high quality of drinking water is important to us. If you have any questions, or would like to discuss further, please feel free to contact us