Authorities responded to the scene shortly after 1 p.m. when they received a call about flooding. The pipe burst next to a home on Clover Hill Lane, just above several homes on the 25700 block of Via Lomas.
About 60 residents in several fourplexes were evacuated due to a potential landslide.
"What we fear and the reason why we have evacuated as a precaution is this hill could slide and affect the homes that are down below," said Division Chief Kris Concepcion with the Orange County Fire Authority. "Also, it could take out and undermine the foundation of this home that is up on top of the hill."
Thousands of gallons of water gushed from the ruptured water main, flooding the yards of nearby homes and frightening residents. Most evacuees grabbed a few personal belongings and got out quickly.
"I heard what I thought were the sprinklers," said evacuee Robert Rodman. "I went outside, saw water coming down the hill. It was coming down really fast. I went up the hill and found where the water break was. One of the neighbors from up above called the fire department."
Firefighters said water flowed from the 10-inch pipe for about an hour before it was shut off. A short time after their houses were declared safe, residents were allowed to return home.
"We had a geologist come out, looked at the hillside and determined that it was intact and OK for the residents to come back in," said Todd Novacek with the Moulton Niguel Water District.