First, turn off all the water on the property. Check your water meter
(usually located near the street) and see if the small triangle or asterisk on the face of the dial is moving. If it is, you have a leak. You may be able to isolate the leak by turning off the house valve and checking to see if the meter dial has stopped moving. Leaks should be fixed as soon as possible to avoid excessive water charges.
For further assistance Mon-Fri between 8am-4pm call Public Services at (650) 903-6329. For assistance on weekends and after-hours, call (650) 903-6395.