PVC cooling tower fill is a type of heat exchange media made from PVC (polyvinyl chloride) material. The fill is typically installed in the cooling tower's heat exchange section, where it facilitates heat transfer between hot water and the surrounding air.Fills are normally made of polypropylene, PVC, or wood. Cooling tower fill is also known as a wet deck or surface, it is a medium to increase the surface area of the industrial cooling towers for the water.