The water main problem was first spotted near a tunnel underneath Concourse B late Sunday afternoon, after a report of a fire alarm sounding near a Georgia Power utility tunnel.
Firefighters who responded discovered water leaking through seams in the pavement, according to the airport. Officials determined the leak was coming from a break in an eight-inch potable water line for Concourse B.
The leaky portion of the line was closed late Sunday night, while the rest of the line is working and providing water to the south half of the concourse.
Hartsfield-Jackson officials said the water released by the leak eventually receded. They said repairs to the water main are underway but it was yet to be determined how long the repairs would take. Also underway is an investigation into the cause of the water main break.