Cooling tower chlorination with chlorine dioxide (ClO₂) is the most effective method for controlling Legionella, biofilm, and microbial growth in evaporative cooling systems. ChloroKlean supplies BPR-authorised liquid chlorine dioxide biocides that activate in-situ without generators, providing superior performance to traditional chlorine across all cooling system types.
Effective cooling tower chlorination using chlorine dioxide provides superior biofilm control and Legionella prevention — without the drawbacks of traditional chlorine.
Cooling towers are inherently vulnerable to microbial contamination. Warm water, large surface areas, and constant aeration create ideal conditions for bacteria and biofilm to thrive — making robust cooling tower chlorination essential.
Cooling towers create ideal warm, wet conditions for biofilm to colonise fill packs, pipework, and basins. Biofilm shields harmful bacteria from conventional biocides.
Poorly treated cooling systems are a high-risk source of Legionella pneumophila. Aerosol drift can spread the bacterium over considerable distances, posing serious public health risks.
Microbiologically influenced corrosion (MIC) beneath biofilms causes pitting damage to heat exchangers and pipework, leading to unplanned maintenance shutdowns.
Biofilm is more insulating than mineral scale. Even a thin layer on condenser tubes significantly reduces cooling efficiency and increases energy costs.
Chlorine dioxide (ClO₂) is increasingly recognised as the superior biocide for cooling tower chlorination, outperforming traditional chlorine and bromine in virtually every measurable category.
Chlorine dioxide penetrates biofilm layers that chlorine and bromine cannot reach, destroying the protective matrix and the bacteria sheltering within it.
Unlike chlorine, which loses biocidal activity above pH 7.5, chlorine dioxide remains equally effective from pH 4 to 10 — ideal for cooling water circuits with variable chemistry.
Cooling tower chlorination with ClO₂ does not form trihalomethanes (THMs) or haloacetic acids, making drift and blowdown discharge safer for the environment.
Chlorine dioxide is less corrosive than equivalent doses of hypochlorite, helping extend the service life of heat exchangers, fill packs, and distribution pipework.
ChloroKlean Plus generates chlorine dioxide in-situ within the water, meaning it is not gassed off over the tower like traditional ClO₂ generators, so residual biocide lasts longer.
ChloroKlean liquid products activate in the water without expensive on-site generation equipment, reducing capital cost and eliminating generator maintenance.
ChloroKlean's cooling tower chlorination solutions are suitable for all types of evaporative cooling and water-cooled systems.
Open Recirculating Cooling Towers
Evaporative Condensers
Once-Through Cooling Systems
Closed Loop Chilled Water
Hybrid Cooling Systems
Air Washers & Humidifiers
Cooling tower chlorination in the UK is subject to strict health and safety legislation. ChloroKlean products and support help you meet every requirement.
HSE guidance for the control of Legionella in evaporative cooling systems including cooling towers and evaporative condensers.
Approved Code of Practice for the control of Legionella bacteria in water systems. Places legal duties on employers and building managers.
Water quality risk assessment for Legionella control. Provides a framework for assessing and managing risk in cooling water systems.
All ChloroKlean products hold UK Biocidal Products Regulation authorisation, ensuring legal compliance for use as cooling water biocides.
"Cooling tower chlorination with chlorine dioxide offers a step change from traditional chlorine and bromine programmes. ClO₂ penetrates biofilm, maintains residual across the circuit, and doesn't produce the harmful byproducts associated with conventional chlorination."
Gavin Owen, Managing Director, ChloroKlean
Common questions about cooling tower chlorination and chlorine dioxide treatment.
See how ChloroKlean Plus eliminated biofilm and achieved sustained Legionella control where conventional biocides failed.
Read case studyCompare chlorine dioxide with traditional chlorine for cooling tower and water treatment applications.
Compare nowContact our team for product recommendations, dosing guidance, and technical support for your cooling tower water treatment programme.