The broken main ruptured at Newport Boulevard and Via Lido at about 1 a.m., sending gallons of water into the streets.
"It ran for over an hour, flooded about a half a block in each direction," said George Murdock, utility director of Newport Beach.
Murdoch said luckily, there was no local damage because the storm drains were able to take the water, and firefighters and city crews were on scene quickly to sandbag the businesses.
When the water was finally shut off, the extent of the damage became clear.
Crews would not only have to replace a 20-inch main water line that was broken, but a big part of the roadway, too.
"There's a void under that street somewhere, so when we start to remove the asphalt, the asphalt will fall into the void, then we have to rake that asphalt out of the void," said Ed Bort from the city of Newport Beach.
Bort said it will also take time to cut the pipes because it takes special saws.
A trench had been dug before the water main broke as part of an ongoing construction project, and some business owners think it's what saved them from any damage. The water went in the trench instead of their businesses.
"As far as we can tell, we haven't walked every single inch, we haven't noticed anything," said merchant Ron Remmer.
"I think we were fortunate because there was a 3-foot trench around in the street and it absorbed most of the water, it came within a foot or two of the door," said merchant Silvano Di Genova.
Orange County crews said the water main break is not unusual, and the main was just an old pipe.