The Port Authority of NY and New Jersey said a water pipe that feeds the terminal's sprinkler system broke around 2 p.m.
In a statement, Port Authority Executive Director Rick Cotton said the break "appeared to be weather-related" and called it "unacceptable". After the flooding began, power to the affected areas of the terminal was shut off for safety reasons.
Rick Cotton said Monday the Port Authority of NY and New Jersey will thoroughly investigate what went wrong and why during the past four days.
The terminal was accepting no worldwide arrivals for much of the afternoon, but around 7:45 p.m. ET, the airport said it was resuming operations.
The break happened just before 2 p.m. Sunday in the airport's Terminal 4, which serves roughly 34 global and domestic carriers.
More delays have been added Sunday to the storm-related aftermath the already beleaguered airport is working to recover from.
Worldwide arrivals to Terminal 4 were suspended earlier, with passengers who were already arrived being taken to other terminals for processing. "There has been no impact on departures and [the airport shuttle] as far as we know".
It was unclear what caused the water problem, which sent about 3 inches of it into the terminal's west end.
Abrams video showed water on the ground in the arrivals area of the terminal and the chaos as travelers attempted a mass exodus from the airport.
While all runways and taxiways had been ploughed clear of snow and reopened by Sunday, inbound flights faced 21/2-hour delays as the federal and local authorities carefully managed the flow of traffic at New York City's main global travel gateway, according to the US Federal Aviation Administration's website. Hundreds of flights were canceled, and hundreds more were delayed or rerouted as authorities sought safe refuge for planes before, during and after the storm.