A molded container assembly includes a pallet, a molded container, and a plurality of connection systems. The pallet supports the molded container thereon and includes stacking alignment structure for stacking the pallet on another molded container assembly. The molded container includes a tank portion, several leg supports, several buttresses, and several horizontally extending ribs. The tank portion includes several curved sidewalls and a fill opening. The leg supports include lower and upper sections that extend above the fill opening for spacing a pallet stacked on top of the molded container above the fill opening. The upper sections include pallet engaging structure for engaging pallets of at least two different types. The horizontally extending ribs minimize outward deflection due to hydrostatic loading and/or pressurization. The connection systems include washers that allow for shrinkage and expansion between the molded container and the pallet in a number of directions.