A broken water main flooded the Court Street subway station in Brooklyn Heights on Thursday afternoon just ahead of rush hour.
The ankle-deep water that poured down from Montague Street and into the station caused extensive delays and service changes to the R & Q trains, city officials said.
The city Department of Environmental Protection tracked the leak to a 12-inch pipe at 156 Montague St., which workers spent hours trying to repair.
R trains were running on the Q line from Canal Street to DeKalb Avenue in both directions. Commuters were advised to use the B26, B38 and B52 buses for alternate service.
About 25 businesses in the area were without water until the repairs could be finished.