Abstract: An evaporative cooling system includes a belt of a material to which a liquid may cling and which is sufficiently transparent to the flow of air therethrough to achieve evaporation of the liquid on the belt by the air. A portion of the belt dips into a reservoir of water. Air is propelled through the belt and the belt is moved through the water. A float valve is responsive to the level of water in the reservoir for maintaining that level upon receipt of an input flow of the water. A separate sump contains a reserve supply of the water. A pump is operated along with operation to move the belt for supplying liquid from the sump through the float to the reservoir.