There is no timetable on the fix, but on Sunday St. Helena flushed 400,000 gallons of water through the system in an effort to fix the problem in the short-term.
Traffic has been backed up along a stretch of Ygnacio Valley Road in Walnut Creek since Thursday as crews continue to work on repairing a water main break, which isn't expected to be finished until Saturday morning.
The culprit was a cast iron pipe that was installed in 1941. The San Francisco Public Utilities Commission said they were already planning to replace it before it ruptured.
A water main break in Alameda that flooded a three-block area and caused sinkholes is under control after crews found a 12-inch cast iron leak in an 85-year-old pipe.
Multiple crews are at the scene of a water main break in the city of Alameda on Sunday evening, the fire department said.
San Francisco's Castro District was drying out Sunday after a water main break suddenly sent water gushing down the street, taking residents by surprise.