The Southeast Delco School District's Kindergarten Center was closed Monday after officials found water pooled on the roof of the building in Glenolden.
Initial reports indicated as much as four feet of water had pooled on the roof after heavy rains over the weekend.
Officials ordered the building closed to check for structural damage.
The school has about 300 students. The district draws students from Glenolden, Collingdale, Darby Township, Folcroft, and Sharon Hill.
Last month, days of rains flooded South Philadelphia's Academy at Palumbo, closing the magnet high school and forcing crews to pull down ceilings to make repairs.