• Lisamarie Lamb

How To Manage The Legionella Risk In Cooling Towers

One of the biggest concerns that building managers have when it comes to controlling the risk of legionella bacteria in their buildings is usually the domestic waters. This makes sense; after all, it is this water that their employees, visitors, and members of the public are most likely to come into contact with, and therefore the water that is most likely to cause a problem regarding legionnaires’ disease.


Or is it?


Although it may seem that way, if your building has a cooling tower then it is this that can be most dangerous. When you think about it, the excess water from cooling towers comes in the form of steam which is basically tiny droplets of water. As we’ve discussed in previous blogs, legionnaires’ disease can only be caught by breathing in droplets of water infected with the bacteria, so the steam from a cooling tower is the ideal place for this bacteria to sit. Because it can drift a long way – maybe many miles – the potential for damage is huge. If infected water droplets from your cooling tower travel over a wide distance and many members of the public breathe in air contaminated with these droplets, some of them will become unwell (possibly seriously, even fatally) with legionnaires’ disease.


This is why the treatment of your cooling tower and working out ways to reduce and ideally eliminate the risk of legionella bacteria within it should always be a priority when it comes to the maintenance and management of any building.



Cooling Towers

A cooling tower contains a large pool of warm water which is just the right temperature for legionella bacteria to breed, particularly because this water is in an enclosed space. When the tower diffuses heat the evaporated water leaves the top of the tower as a fine mist. Depending on weather conditions and other environmental factors as well as location, this can then travel a long way as mentioned previously.


The first thing to do is to check that your cooling tower is being maintained properly. If it contains algae or scale then there is clearly a problem with the treatment of the tower. It is always wise to speak to a professional such as those at Assured Water Hygiene to ensure that the towers you are responsible for are being looked after in the right way, so as to reduce the risk of bacteria growing within them as much as possible.


Proper Water Treatment

Although nothing can be done about the way that a cooling tower works (in other words, it is always going to produce that fine mist, and that mist is always going to travel at least a little way), a lot can be done to ensure that it is not a danger to anyone. Good maintenance and regular cleans of the tower will ensure that legionella bacteria doesn’t have a chance to grow within the tower; cleans every six months are the minimum you should be thinking about, but quarterly cleans will reduce the risk even more.


When the cooling towers are cleaned, any scale and algae should be completely removed, and then the tower should be treated with a biocide. Anything within your cooling towers that is corroded such as drift eliminators should be replaced as soon as possible – legionella bacteria loves to breed on rust.



Use A Professional

Cooling towers are not a place for those without the correct training or sufficient knowledge to be. If you are implementing a cleaning regime (which you certainly should be) then you must also use professionals who know how to clean cooling towers and can ensure that the job is done safely and efficiently.


Don’t Forget To Test

It’s hugely important to test your cooling towers for legionella bacteria between cleans. Monthly testing will ensure you get a full picture of exactly what is happening – there is no point in not testing and hoping all is well when you could be fixing problems that will lead to much bigger issues.


Again, use a professional to carry out this testing for you – Assured Water Hygiene has been sampling cooling towers for over 30 years, and has plenty of experience. The samples need to be tested by a UKAS accredited lab, and the results should be sent out immediately. If any interim cleans need to be done, you will know about it and can plan any works that are required.

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