It unleashed huge amounts of water onto nearby streets, impacting some homes and even closing the westbound on-ramp to Interstate 580.
But the water main break is just a symptom in this case of a much bigger problem. On Montana Street in Oakland, the problem of aging infrastructure has come home to rust, again.
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"Oh, it was water everywhere," said one resident.
All the garbage bags were floating.
"It's a huge, huge mess," said Veronica Bonilla, whose family's living space was under water at 7:30 a.m. Friday.
"Once I saw the water, it was déj vu because it has happened before," she said. "This is the third time, and it is the worst."
The last time was December 2014.
"We respond to 800 to 1000 main breaks each year, so remembering each one can be difficult," explained Nelsy Rodriguez with East Bay MUD.
East Bay MUD says the broken main was made of cast-iron - and is almost 100 years old. It is exactly the kind of main that the utility is replacing at a rate of 10 miles a year, with thousands of miles to go.
"All they are doing is patching, not addressing the full problem. The street needs to be redone and they need to do it," said Dennie Rupe, who lives in the area.
Instead, East Bay MUD worked on yet another patch. "Potentially, we need to replace the entire main. It could happen tomorrow again," said Rodriquez.
"We are considering moving. We are going to move," said another neighbor.