On Sunday, just as there were signs that things were finally improving, a water main break in a terminal plunged the airport back into chaos. The flooding — three inches in parts of Terminal 4 — compounded the confusion that had gripped parts of Kennedy all weekend, as airlines tried to rebound from the cancellation of thousands of flights because of the storm. Officials of the Port Authority of New York and New Jersey, which operates Kennedy Airport, were still trying to sort out what had gone wrong on Saturday when they had to scramble on Sunday to cope with the burst pipe.

In a news conference on Sunday evening, Rick Cotton, the executive director of the Port Authority, said that he was ordering an investigation of the water main break and the continuing flight problems. He emphasized that the terminal with the flooding was operated by a private company, not the Port Authority.

For the second day in a row, the Port Authority had to ask federal aviation officials to block some international flights from landing at Kennedy. That order would add to the two dozen flights that had been diverted to other airports since Saturday.

The protracted chaos at the airport drew harsh condemnation from Senator Chuck Schumer, who called for “a thorough review” of the airport and the Port Authority to find out what went wrong, especially since Thursday’s storm had not come as a surprise.

“They should have been way better prepared, plain and simple,” he said. “J.F.K. has to follow the Boy Scouts’ motto: ‘Be prepared.’ They weren’t.”