An evaporative cooling tower works by using the cooling effect of evaporating water to boost the cooling provided by fresh air. As warm water from the chiller is pumped to the top of the tower, it is sprayed over a fill material, allowing some of the water to evaporate. This evaporation process cools the remaining water, which is then collected at the bottom of the tower and re-circulated to the chiller. The cooled water is then used to cool the building or process.