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How to Service and Maintain Cooling Towers to Avoid Legionella

Most cooling towers are likely to become contaminated with Legionella at some point in their serviceable life. The public health risk posed by Legionella bacteria can be addressed by implementing preventative measures, such as a good management plan, which substantially reduce the risks.

This article provides the steps to develop a management plan which includes a detailed and systematic assessment and prioritisation of hazards, as well as operational monitoring of barriers and control measures when looking at how to service and maintain cooling towers.

Management plan to service and maintain cooling towers

Document and describe the cooling tower

  • Assemble a team to conduct the cooling tower assessment which may include, but is not limited to:
    • Building owner
    • Water treatment specialist
    • Site manager
    • Building engineer
    • WHS officer
  • Items to be assessed include, but are not limited to:
    • Quality of water entering the system
    • Design of the devices and distribution system
    • Nutrient sources
    • People who are using the system, including potential users
    • Management structure
    • Competence of personnel responsible for the system

Assess hazards and prioritise Legionella risks

  • Collect and evaluate information regarding hazards and conditions that have led to their presence and decide on their significance in regard to generating a management plan
  • Items to be assessed include, but are not limited to:
    • Water quality
    • Water treatment
    • Disinfection
    • Biofilms
    • Temperature
    • Cooling tower design and material used in construction

Identify opportunities to control Legionella

Detail control measure for all risks identified from the previous step.

For example, this may include control measures such as cleaning and maintenance which addresses regular visual inspections, routine cleaning and disinfection and the implementation of water treatment chemicals to minimize scale and corrosion.

Implement Legionella control measures

Using the prioritised list of risks and starting from the top, create an action plan to implement the control measures.

The action plan should include:

  • Risk description
  • Risk rating
  • Control Measures
  • Person responsible
  • Timeframe for completion
  • Section to state whether the control measure is in progress, completed or superseded

Monitor Legionella control measures

This step defines the limits of acceptable performance and how this will be monitored which is best performed in conjunction with a water treatment specialist. Many of the control measures identified to minimize risks will form a procedure for monitoring as they will involve testing and collating information.

This may include water sampling to monitor:

  • Legionella concentrations
  • pH levels
  • Water temperature and
  • Alkalinity

Develop Legionella management procedures

The prevention and control of Legionella in cooling towers requires the preparation of management documents that include corrective actions for normal and incident conditions. This document should provide instructions for a continuous loop of routine monitoring and corrective action.

Legionella auditing and surveillance

  • As part of regular auditing the water treatment specialist should conduct sampling and testing at least monthly, and in line with regulations
  • A good management plan will have a process for a regular formal independent review
  • Details of maintenance and performance should be recorded to ensure faults are identified, procedures are adhered to and that there is historical data to refer to.

Chemology has over 10 years’ experience and knowledge in the water treatment industry, supplying water treatment specialists with chemicals to control and fix Legionella outbreaks in cooling towers.

We also have many years experience working with water treatment specialists on how to service and maintain cooling towers to best practice methods.

Contact one of our friendly team today on (08) 8326 6170 or click HERE to fill out a contact form for more assistance on how to control legionella in a cooling tower!


Image: “Water Treatment Center” by Joe Jungmann accessed via Flickr 3/7/18