Cooling towers rely on evaporating water to discharge heat into the atmosphere. But the same warm, moist environment that makes them efficient also makes them ideal breeding grounds for one of the most dangerous waterborne bacteria: Legionella. Every year, it hospitalizes thousands and has been linked to severe outbreaks traced back to neglected or poorly monitored towers. The true challenge in cooling towers lies beneath the surface – biofilm. This slimy layer thrives in moist environments, forming on internal surfaces and shields bacteria like Legionella from disinfection. Unless biofilm is removed or controlled, even the most aggressive chemical treatment remains a temporary fix.
In Europe alone, Legionaire’s disease – which is caused by airborne Legionella bacteria present in water molecules – affected more than 10,700 people in 2021 according to an ECDC report, the highest rate seen to date.
Cooling towers are also tightly regulated because of that risk. In Europe, guidance from the ECDC and national standards like the UK’s HSG274 require regular testing, risk assessments, and documented maintenance plans. In the U.S., ASHRAE 188 and OSHA have set similar expectations for water management. For industrial plants, neglecting these regulations can not only lead to shutdowns of the plants and fines, but also lasting reputational damage if a legionella outbreak is traced back to their site.
The Human Impact of Legionella
Legionella infections aren’t just numbers on a chart. Legionnaire’s disease can cause severe pneumonia, high fever, and respiratory failure, with a mortality rate ranging from 5–10% in hospitalized cases. Outbreaks can quickly overwhelm local health systems and trigger expensive shutdowns of contaminated facilities, underscoring the importance of early detection and proactive monitoring.
Why Traditional Testing Falls Short
Despite decades of regulations and regular water sampling, the risk persists. Traditional testing tells operators when Legionella is already there, not when conditions are turning dangerous. Traditional testing methods are only reactive, not proactive. Predicting those conditions before the bacteria appear is the next barrier to cross in public health protection.
Legionella doesn’t appear overnight though, it quietly builds up over time within the very systems designed to keep industrial plants running. Inside such systems, warm water circulates through large volumes of pipework, collecting organic matter and sediment along the way. Stagnant water combined with sediment build-up and low deterrent products may lead to contaminated aerosolidated water causing sporadic cases or outbreaks of Legionella.
Limitations of Current Monitoring Systems
The problem often found in modern monitoring systems, is that it rarely sees this coming. Laboratory tests often take too long, and frequently inconsistent, with improper sampling techniques, degradation of samples during transportation, and inconsistencies in analytical methods between differing laboratories being oft too common. By the time a positive test arrives, the bacteria have already spread through the tower’s mist. The best that can be done is only reactionary; operators dose more chemicals, and hope the counts fall.
Traditional monitoring leaves operators one step behind the bacteria. Bridging this gap requires a proactive, data-driven approach to managing Legionella risk. To move from reaction to prevention, operators need predictive tools that spot risk early. Liquisens Predict provides that exact solution. By implementing the use of automated data tracking, Liquisens Predict provides water managers with more information to optimize and improve their overall processes. This allows the operators to control the water management in real-time, allowing for rapid responses to process upsets throughout the entire chain, providing insights crucially needed to optimize chemical dosing.
The defining feature of the Liquisens Predict approach is the ability to apply more effective, efficient and sustainable Legionella risk management in comparison to more traditional methods. By analyzing key risk factors for targeted action, the system ensures lower chemical consumption and increased safety.
Real-World Success: Agfa-Gevaert
The results of the combined predictive modeling and sustainable treatment approach is evident in the case of Agfa-Gevaert, a Belgian-German multinational specializing in imaging systems, software, and IT solutions. With predictive modeling implemented in the plants cooling towers, a structural reduction of Legionella risks was found, combined with a 50% reduction in biocide use, while still ensuring proper water safety. This amounted to an annual chemical savings of €10,000 per year.
The Future of Cooling Tower Management
Like most public health issues, Legionella outbreaks are preventable. These outbreaks carry significant health, regulatory and reputational consequences. Liquisens Predict offers operators the tools to improve water safety at their facilities and helps them prevent incidents before they occur. Efficiency is a key factor in preventing Legionella outbreaks, which is an element that has largely been absent in keeping water safety in cooling towers. Intelligent, data-driven cooling tower management that embrace predictive, sustainable, and real-time solutions should be the standard moving forward.