The busted 8-inch main was reported around 2:40 a.m. in the 11000 block of Borden Avenue, according to the Los Angeles Department of Water and Power.
This is the second day in a row that LADWP crews have responded to this location.
Tuesday, there was a much smaller leak. An LADWP official told Eyewitness News that crews came, made repairs and then left for the evening with plans to return Wednesday morning to finish their work.
But overnight, the bigger break occurred in the same area - flooding several neighborhood blocks.
"Sometimes, it just happens. One part of town, you get a couple of main leaks on the same day. I'm guessing it's probably based on age and soil conditions," said Michael Chavez with LADWP.
Across the street, Sara Coughlin Elementary School was without water service as parents dropped off their kids.
"The crew is doing everything that they can in order to get it resolved as quickly as possible," said Leticia Sanchez, the school's principal. "We have water, food and portable restrooms on their way."
By 10 a.m., a flatbed full of portable toilets and hand-washing stations arrived, some two hours after the opening bell.
Kids at Sara Coughlin Elementary in Pacoima will use porta-potties & receive water bottles after water main break. pic.twitter.com/3jEqazgBsu— Marc Cota-Robles (@ABC7MarcCR) August 26, 2015
In all, officials said service for 16 customers were interrupted. All service has since been restored.
City News Service contributed to this report.