Each day we watered our butterfly garden there would be a pond in the hallway by the fifth grade lockers. This happened more than once. The maintenance men weren't positive where it was coming from. They finally figured out that the water was traveling through a crack in the concrete all the way down the hall to the fifth grade lockers. They filled the hole with styrofoam and some gooey, white stuff. We started watering again and we haven't had any more problems.