Why is water treatment important in an evaporative cooling system?

Effective water treatment works to control scale, corrosion, and microbiological growth within an evaporative cooling system. It also helps to ensure heat transfer efficiency and extend the service life of the equipment.

When an evaporative cooling system rejects heat to the atmosphere, only pure water is evaporated. As this occurs, the dissolved ions—naturally occurring in the makeup water source—are left behind. Without proper water treatment, the dissolved ion concentration increases as evaporation continues and, at some point, will reach saturation of the ions, which can lead to scale. The most common form of scale is calcium carbonate. Preventing scale via water treatment impacts the efficiency of heat transfer, thereby reducing energy consumption of the entire system. 

Water is known as the universal solvent given its affinity to bind with other ions. In an evaporative system made up of a variety of metals, this leads to corrosion of the materials of construction. Any quality water treatment program will attempt to reduce the corrosion rates of each metal found in the system, to ensure an acceptable lifespan of the equipment. Some common metallurgies found in evaporative cooling systems include copper, galvanized steel, carbon steel, and stainless steel.  

Microbiological growth in evaporative systems can lead to accelerated corrosion rates, heat transfer deficiencies due to biofilm, as well as human health related concerns. There are a variety of reasons why one system may experience higher biological activity than another. Tower location, nearby construction or farming operations, the makeup water source, and more can all lead to an increased level of bacteria in the water. For information on specific water treatment options, please contact your local EVAPCO sales representative