Here we describes counterflow cooling towers, the most common type of cooling tower used in industry. the draft is induced by a fan placed at the top of the tower drawing the cooling air. counterflow means, the flow of air is parallel and opposite in direction to the flow of the water being cooled. this results in a greater thermal efficiency than crossflow designs. the internal structure of a 2 cell counterflow cooling tower shown here is made of wood to lower capital costs. California Redwood is used because it has a natural resistance to decay and insect attack.