A Dozen Water Mains Break Across San Francisco in Two Week Span – Here’s Why

With the holiday season upon us, that means colder weather, which has been a key factor in the recent strings of water main breaks happening throughout San Francisco. 

Earlier this morning, there was an 8 inch water main break in the Sunset on Noriega near 18th Avenue in the City. This was the latest of 12 breaks that have happened in San Francisco in the past two weeks. And while that number may seem high, it’s not all that unusual for this time of year. Change in temperature and wet ground conditions are highly related to increases in number of water main breaks.

“When we have these breaks, our main objective is to preserve public health and safety. After that, our next goal is to maintain water service, or return service as soon as possible,” said Suzanne Gautier, SFPUC Communications Manager.

SFPUC crews arrived on scene shortly after the water main break occurred.
SFPUC crews arrived on scene shortly after the water main break occurred.

Today’s water main break was a cast iron pipe that had been installed in 1932. Temporary water service interruptions impacted two blocks of Noriega, from 17th Avenue to 19th Avenue, as well as one block of 18th Avenue from Moraga to Noriega. SFPUC crews responded to the water main break by repairing the pipe with the installation of a 15-foot length of new ductile iron pipe. Water service was restored back in the area before noon.

On average, there are about 130 large main breaks each year and more are expected this coming winter with the cold and rainy weather. San Francisco has over 1,200 miles of pipeline under the streets, with more than 100 miles of pipes dating back 100 years old. The SFPUC is replacing 12 miles of pipe per year with stronger and more earthquake resistant ductile iron pipe.

Since San Francisco is an older city, these main breaks and temporary service interruptions are expected to continue at a steady rate for years to come. To manage and minimize these service outages, the SFPUC has staff on duty 24 hours per day, 7 days per week.

The SFPUC typically responds to main breaks and halt any flooding within one hour and aims to repair the pipeline within four to eight hours. Frequently, water service is not affected by these breaks since there are built-in redundancy in the system. However, when service interruptions occur, the SFPUC works around the clock to minimize disruption as quickly as possible.

“After a water main break, your water can appear to look “dirty” with particles or brown in color due to the presence of rust or sediment from somewhere in the water system,” said Gautier. “Run your cold water tap for a few minutes to flush out the sediment. If the sediment persists, wait one hour and run the cold water tap again. If you experience any change in water pressure, color or odor, please call 3-1-1.”