Orange Water and Sewer Authority officials are sill not sure what caused a major water main break on a chilly morning last week that led to the loss of about 500,000 gallons or roughly 7 percent of the utility’s daily water consumption.

Officials said the break in an 8 inch diameter water main near the intersection of Martin Luther King Jr. Boulevard and North Street happened at about 1:20 a.m. OWASA crews responded and shut off water in the area at about 3:30 a.m. and closed the street.

About 100 OWASA customers in the North Street-Cobb Terrace area were without water until the break could be repaired.

Another leak, this time spilling an estimated 5,000 to 8,000 gallons of water, was reported earlier this week after tree root damage led to a water main break near Cameron Avenue and Roberson Street.

—Kirk Ross