The governing board of every school district shall provide, as an integral part of each school building, or as part of at least one building of a group of separate buildings, sufficient patent flush water closets for the use of the pupils. In school districts where the water supply is inadequate, chemical water closets may be substituted for patent flush water closets by the board.

This section shall apply to all buildings existing on September 19, 1947, or constructed after such date.