top of page

The Importance of Cooling Tower Cleaning and System Maintenance

Updated: Sep 12, 2023

By: Ben Feeney, Chemical Engineer

Cooling towers play a critical role in HVAC systems. As water passes over the tower, fans blow air upstream against the falling water droplets, causing the water to evaporate and cool. While cooling towers do a good job at lowering water temperature and rejecting heat, they also act like giant air scrubbers. Often located outside of a building, they scrub dirt, silt, pollen, microbes, and other debris from the air into the HVAC system. Most building engineers realize the importance of regular cooling tower cleaning and maintenance to promote system longevity and efficiency. A dirty tower can quickly lead to systemwide contamination. Here are some of the benefits of regular tower cleanings.

Reduced Bacteria Counts

Bacteria need nutrients just like us. Dirty cooling towers are a perfect home for algae, biofilm, sulfate-reducing bacteria, and iron-reducing bacteria - to name a few. As the diversity of bacteria increases, they can become insulated under dirt and slimy biofilm. This makes it hard to eradicate bacteria using traditional chemical biocides. In some cases, dangerous Legionella bacteria counts will increase, leading to major health and safety issues. If someone in the vicinity of a cooling tower breaths in water droplets containing Legionella bacteria, they may contract Pontiac fever or Legionnaires disease. Aside from Legionella, algae can grow into large mats that break off and clog screens, strainers and other equipment, causing disruption.

Lowered Risk of Equipment Fouling

A buildup of debris in stagnant areas like equalizing lines, drains, side stream filters, and offline equipment can lead to a loss of efficiency. Fouled fans and chillers cause a reduction in heat transfer. Pumps have to work harder to keep the same temperature differential. Fouled fill and plugged spray nozzles affect the water spray pattern and chemical treatment distribution. If water does not flow through the tower evenly, dry areas can become dirty with calcium scale and bacteria since water treatment chemicals are not reaching these areas.

Better Optics

A clean cooling tower looks better to those passing by as well as building owners and occupants. It indicates good housekeeping measures by management and shows care has been taken to ensure the overall health and safety of those who work there.

Increased Equipment Life

The most obvious reason to disinfect and clean cooling towers is to increase the lifespan of the equipment. As with any piece of equipment, regular and consistent maintenance is necessary to maximize equipment life and efficiency.

How often should a cooling tower be cleaned?

OSHA recommends cooling towers be cleaned and disinfected at least twice a year (source link). More frequent cleaning and disinfection may be required if inspections show visible microbiological growth or an excessive buildup of debris, or as a remedial measure in response to positive Legionella or bacteria test results.

Tower cleanings are labor intensive and disinfection utilizing specialized chemicals may be necessary to remove many deposits. For best results, always use a company trained and specialized in tower cleaning work.

Reach out to our Water Technologies team at Boland for a free customized quote! Call us at (240) 306-3000 or email us at


bottom of page