Legionella in Cooling Towers – The Hidden Threat

Cooling towers are a common in industrial settings, serving a crucial role in regulating indoor temperatures and maintaining processes. However, amid their efficiency lies a hidden danger – Legionella, a harmful bacterium that can thrive in these systems. In this blog, we’ll explore why it’s necessary to be cautious of Legionella in cooling towers and the measures we can take to mitigate this threat.

Understanding Legionella

Legionella is the bacteria responsible for Legionnaires’ disease, a severe form of pneumonia that can be fatal, especially for individuals with weakened immune systems, the elderly, or those with underlying health conditions. Cooling towers provide an ideal breeding ground for Legionella due to their warm, humid environment – conditions that enable these bacteria to multiply rapidly.

The Risks

When Legionella-contaminated water droplets are inhaled, especially through contaminated aerosols dispersed by cooling towers, they can cause severe respiratory illnesses. Cooling towers release warm air into the atmosphere, creating a fine mist or droplets of water and if these droplets are contaminated with Legionella bacteria, they can reach the lungs and cause infections. This aerosolized form of transmission is highly efficient, especially in crowded urban areas where cooling towers are common on buildings.

Prevention is Key

See below some of the key things which can be done to help mitigate the risk of Legionella in your cooling tower:

Regular Maintenance: Implementing a robust maintenance schedule is crucial. Regular cleaning, disinfection, and removal of biofilms can significantly reduce the risk of Legionella proliferation.

Water Treatment: Employing appropriate water treatment methods, such as biocides and chemical inhibitors, can help control bacterial growth in cooling towers.

Temperature Control: Maintaining water at temperatures outside the ideal range for Legionella growth (typically below 20°C or above 60°C) can inhibit bacterial colonization.

Monitoring and Testing: Regularly monitoring water quality and conducting Legionella testing can provide early detection, enabling swift corrective action.

Proper Ventilation: Ensuring proper ventilation systems are in place can minimize the dispersion of contaminated aerosols, reducing the risk of inhalation.

Educating Personnel: Training those responsible for cooling tower maintenance about the risks associated with Legionella and the importance of following established protocols is essential.



Legionella in cooling towers poses a significant health risk that demands attention and action. By understanding the conditions that foster Legionella growth and implementing rigorous preventive measures, we can safeguard not only the efficiency of our cooling systems but also the well-being of the people who inhabit or work in the buildings where these systems are installed.

If a cooling tower is contaminated with Legionella and goes unnoticed or untreated, it can lead to outbreaks of Legionnaires’ disease and such outbreaks can be challenging to contain. This can affect a significant number of people, leading to public health concerns and substantial economic costs for your company.

Vigilance, education, and proactive maintenance are our best defenses against this hidden threat, ensuring a safer environment for everyone.