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  • Lisamarie Lamb

How To Have A Clean Cold Water Storage Tank

As you probably already know, legionella bacteria (as well as plenty of other bacteria and germs) live happily in cold water storage tanks. In fact, these tanks can be the ideal place for legionella to thrive since they can easily be at the right temperature (between 20 and 50 degrees) and can contain rust and other elements that legionella feeds on. This is why you need to keep your tank at the right temperature and why you need to keep it clean. We’ll focus on the latter issue in this blog, and with that in mind, here are some steps to take to ensure you have a clean cold water storage tank.


When it comes to having a clean cold water storage tank, the first thing you need to do is prepare. This doesn’t just mean preparing the tank – although that is important – but also ensuring the people doing the work are prepared as well. It’s best to outsource this work to trained professionals who have expertise in working on clean cold water storage tanks if possible – Assured Water Hygiene can help with this, so please don’t hesitate to contact us.

If you are doing the work yourself, you’ll need to carry out a risk assessment to keep your team safe. Remember that when you are cleaning a cold water storage tank you’re working in a confined space, and this might require specialist equipment, such as breathing apparatus. At the very least, it needs two people to carry out the work for safety.

Drain The Tank

Once you are prepared, you’ll need to drain the tank so that you can clean it. This means that there will be no water to the outlets that the tank serves for the duration of the cleaning, and this could be a number of hours. As part of your preparation, you’ll need to put signage in place to prevent people from using the outlets. It might be more convenient to clean the tank when the building is empty, such as on a weekend or overnight, for example.

Once the tank is drained, it’s a good idea to take photographic evidence to show how dirty it was. You can then take another photo when the work is done to prove that you now have a clean cold water storage tank.

Clean The Tank

The next task is to carry out the clean of the cold water storage tank. Make a note of any issues such as corrosion, scale, or missing elements (such as a lid, insect screens, and so on). These will need to be put right as soon as possible.

To clean the tank you’ll need to scrape down all the surfaces, use a wet vac to vacuum the walls and floor, remove all visible debris, and then wipe down all the surfaces using a ten percent liquid chlorine solution.

In many cases, it’s wise to carry out a complete chemical disinfection of the tank and system – otherwise known as a chlorination. This must be completed by experts and is an added step that will ensure your tank is completely clean. If you are not doing this, you can now refill the tank and recommission the outlets.

Contact Assured Water Hygiene

Having a clean cold water storage tank is vital for the health and safety of your staff and anyone who uses the water within your building. For a full clean and chlorination, please contact us for more advice.

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