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Legionella Audit - Cooling Towers

BY John Herbert | Director

Cooling tower systems under the Water cooled Air conditioning System programme shall be independently audited its required by the Hong Kong Code of Practice.

If regulations are not sufficient, just consider the business risk perspective The evidence is clear. many businesses cease trading after a Legionnaires' Disease (退伍軍人病) outbreak.  

Two examples: 

A factory cooling tower caused an Legionnaires' Disease (退伍軍人病) outbreak, in the adjacent area members of the general public fell ill. Fatalities occurred. Later the recriminations, and legal action followed, within a month the factory was permanently closed.

Another example a decorative water feature in a restaurant caused more than twenty people became ill. The news of the outbreak spread across the globe. After the media hype, it re-opened, but the customers never returned, and another business was forced to close. 

Prevention is better than the cure.

Legionella Audit Approach

To avoid the trauma of a Legionella outbreak the primary tool in our arsenal in the fight against Legionella is regular monitoring, and auditing.

For WACS scheme, an annual audit is a requirement, and failure to do so may result in suspension of the water supply.

An audit is a methodical and systematic assessment of your systems  in your building creating a risk model, and if deficiencies are identified providing recommendations for the necessary remedial works. An audit typically comprises three parts:

  • Data Collection
  • Fieldwork
  • Report

Data Collection - Review the drawings, schematics and logbook records provided, Read and re-read the last auditors report.

Fieldwork - In other countries a paper audit is deemed sufficient. However, I always recommend a site visit, its essential that the auditor can assess the physical condition of the plant in operation. Boots on the ground is my mantra, because it gives the hands on feel of the operation, and it ensures the cooling towers, water treatment, and the water system are operating as intended. But that snapshot, is part of the story, the real skill is assessing the logbook and history. 

Report -  The final stage, the written summary of the findings and recommendations. 



How should one go about doing risk assessment?

I recommend a comprehensive facility survey to assess the risks in the cooling system. 

At my firm Kelcroft we conduct a survey of the client's facilities to check their installation, as per the specifications laid down in or within our scope. We have accumulated detailed checklists to capture site data for the cooling towers equipment, services, log, blowdown, Make-up Water, Existing Treatments, Water Analysis, and Legionella analysis, among other things.

Independant legionella audit in accordance with Code of practice for cooling towers Hong Kong by KelcroftOrder an independent Legionella cooling tower audit every year, in fact the Hong Kong Code of Practice  for Water cooled air conditioning systems demands independent annual audit.

The key factors to consider prevent the infection chain, break the chain prevents harm -  Remember GAI

  • Growth - Don't give Legionella a chance to grow;
  • Atomization - Don't permit / minimize the opportunities for water to atomize;
  • Inhalation - Don't permit receivers, especially susceptible people the opportunity to inhale water droplets;

Yes, Legionella is a risk, but it is a risk easier to manage than many risks face everyday.





About the Author

Mr John Herbert is Managing Director at Kelcroft E&M Limited, he is an internationally recognized Legionella specialist. He has advised clients and audited risk at facilities on three continents. He can be reached at telephone number is +(852) 2335 9830

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