Apparatus for receiving run off water in shopping centers and the like includes an underground storage area from which the stored water percolates into the local aquifer or is pumped out, as desired or as required. Several embodiments of perimeter support structures are illustrated. In one embodiment, a retaining wall is used to support structural tee elements, and in another embodiment caissons are spaced apart and receive L-beams which in turn support structural tee elements. Other embodiments show full vertical walls and stepped walls. The tee elements may be used to support a parking area for vehicles or to provide support for other appropriate uses. An appropriate liner is secured to the perimeter support structure for holding the run off water.