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  • Lisamarie Lamb

Why Is Cleaning and Disinfecting Your Cold Water Storage Tank So Important?

Legionella bacteria is a major risk within buildings and it is something business owners and landlords need to be aware of. It is also a big part of the health and safety guidelines, partly because it is prevalent and will often be found after testing, and partly because – with expert help – it is something that can be dealt with quickly with little fuss and expense (although exactly how much the process will cost will depend on what your risk assessment points out).

One area that should be of high concern is the cold water storage tank or tanks within the building. This is because these areas provide the ideal breeding ground for legionella bacteria. Therefore regular testing of your cold water storage tanks is essential; it will show you if you have a problem.

Something else that is important is the regular cleaning and disinfection of the cold water storage tanks in your building. Here are the reasons why.


Legionella bacteria love stagnant water and it is one of the most likely places to find it. What, though, has this to do with your cold water storage tank? Surely there is no legionella in there? Actually, there are a number of reasons why there might indeed be stagnant water in your cold water storage tank.

The first is that your tank might be too big for your needs. If that is the case, the water in the tank won’t be turned over often enough and it can easily become stagnant. Stagnation can also occur if there is under-utilisation of the water within your building – perhaps some outlets that used to be in use are no longer used. It is also worth checking your system for blockages or poor flow if stagnation is occurring.

Because there is a relatively high chance of finding stagnation within most cold water storage tanks a regular clean and disinfection is going to help immensely.


Cold water storage tanks, no matter how good and tight the lid might be, will become dirty over time. Rust, sediment, silt, and other items of debris will enter the tank and will need to be cleaned away. If the tank is not regularly inspected, other items such as dead animals and birds and organic matter like leaves can even get inside. This debris is ideal food for legionella bacteria, so a regular clean will ensure there is nothing for the bacteria to eat and it will starve and die.

It’s In The Recommendations

If nothing else, cleaning and disinfecting your cold water storage tank is in the Health and Safety Executive’s guide to controlling legionella bacteria, the HSG274. This document recommends cleaning the tank at least annually (and more often if legionella has been detected).

Contacting a professional water hygiene expert who can offer up advice about the best time to clean your tank and even carry out the work for you is the best way to get the work done. You can be sure that the work is being done right and that you can protect those within your building.

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