The rupture was about 1 a.m. beneath Nimitz Boulevard near Shafter Street, between Rosecrans Boulevard and North Harbor Drive.
It was likely due to “corrosion to an old cast iron water main,” according to Arian Collins, spokesman for the City of San Diego Public Utilities Department.
Collins said the broken pipe was installed 70 years ago.
“We’re hoping to have all the cast iron removed by 2017. But it’s a long, expensive process. Right now, they’re breaking faster than we can replace them,” said Collins.
Water service was lost to accounts in the 2600 through 2900 blocks of Nimitz Boulevard, Collins said. Some apartments and homes in the area sustained water damage.
Crews expected to have the pipe repaired and water service restored by 8 p.m., but that was delayed because they had mechanical problems cutting out the old pipe.
Once the sinkhole is filled in, the city’s street division will go in to patch up the road. That section of Nimitz Boulevard will remain closed until at least Monday, Collins said.