Nine water mains ruptured in the East Bay on Monday, mostly in and around the areas affected by a magnitude-4.0 earthquake earlier in the day, according to the East Bay Municipal Water District.
Of the nine, five were located in Oakland in the strong shake zone or at close proximity to the Hayward Fault line, said Abby Figueroa, the district's public information representative. The other four were in areas like Berkeley and Richmond.
"The jolt might have broken pipes, might have surfaced water from an already leaking pipe or maybe made a small leak much bigger," Figueroa said.
Seven of the pipes were repaired Monday and overnight, while the other two were lower-priority lines that will be fixed today, she said.
The average age of cast-iron pipes in the EBMUD system is about 80 years old, with some pipes dating as far back as the 1880s, according to district spokeswoman Tracie Morales-Noisy.
"On average we receive two to three main breaks per day, so this is slightly more than double what we receive on any given Monday," she said. "This has our crews working very hard."
The five breaks located in Oakland were found in older cast iron pipes, which are susceptible to ground movement, Morales-Noisy noted. She said the incident serves as a reminder of the infrastructure hazards of a major seismic event like the Loma Prieta earthquake of 1989.
"We could see hundreds or thousands of main breaks, and it would have an enormous impact," Morales-Noisy said. "We recommend that customers have a minimum of three to seven days worth of water in their home in the event of a major water emergency."
She advised area residents to keep at least one to two gallons of water per day for each person in the home.
"It doesn't have to be a major emergency, it could be just a main break," Morales-Noisy said. "Things are unpredictable, and you never know when you'll need a water supply."