Why Water Tank Cleaning is Critical for Legionella Control?

Water tanks are integral to many industrial processes and are a requirement in nearly all domestic and commercial environments. Efficient operation of these systems is essential to minimising running costs and maintaining production.

Water safety and hygiene are equally important particularly with regard to the control of Legionella bacteria. If your business supplies water for drinking, cooking, cleaning or consumption it is a legal requirement for you to have a legionella risk assessment in place.

A routine inspection of water tanks is, therefore, a critical part of building maintenance and should not be overlooked at any cost.  

Why water tanks are at risk?

Contaminated water poses a risk to human health and so careful attention must be paid towards cleaning water tanks to avoid the prospect of contamination, which can lead to the shutting down of water supplies and closure of businesses.

Water tanks can get contaminated if not installed properly, contain substandard materials, or are old and rusty.

Stagnant, low circulation water sources can be a potential breeding ground for unwanted and harmful bacteria. Stagnation can be caused by several factors including under-utilising water, using an excessively large tank, and issues in your water system causing blockages or poor flow.

Coldwater storage tanks are also a common source of nutrients for biofilm and bacteria, including Legionella. Over time a dirty tank can develop rust, sediment, and silt; unchecked tanks can even become contaminated with organic matter such as leaves and in extreme cases small animals such as rodents.

Another risk is debris coming in from the mains. The tank can act as a catchment area for debris, causing it to harbour nutrients and bacteria.

Choose the Right Water Tank for Your Building

One of the most powerful things you can do when it comes to Legionella prevention is to pick the right tank in the first place.

The type of water storage tank installed makes a difference in how easy it is to maintain a sanitary environment. High-quality GRP water tanks are durable, long-lasting and resist damage. Insulated GRP cold water tanks won’t allow the water to get warm enough for Legionella to breed. They’ll also keep it from getting too cold and freezing.

Where appropriate, outfit your tank with a pump or booster to prevent stagnation. Keeping water moving will reduce the chances of biofilm formation and therefore lower the chances of Legionella growth in your tank.

Control the risk with water tank maintenance

To control the Legionella risk and maintain water hygiene, water storage tanks should be inspected regularly as part of your monitoring programme that was formed in line with your risk assessment.

The traditional strategy for controlling the risk of legionella is through water temperature control. Legionella bacteria are dormant below 20° C and cannot survive above 60° C. Therefore, regular checks need to be undertaken to ensure your cold water tanks store water below 20° C.

These checks can be conducted both at the source and at a selection of outlets. For example, you can run taps to ensure the required temperature is reached within one to two minutes.

There are legal obligations surrounding the inspection and if needed, cleaning and disinfection of tanks must be carried out.

Extensive records of the procedures carried out must be maintained. These records allow you to prove you are taking the correct action to prevent a legionella outbreak.

What’s involved in routine water tank cleaning & disinfection?

At Water Treatment Ireland Ltd, all our water tank cleaning and disinfection work are carried out as per the guidelines by HPSC National Guidelines for the Control of Legionellosis in Ireland and UK HSE’s ACOP L8.

Our water hygiene engineers are fully trained and qualified who follow specific method statements and procedure to ensure the work complies with health and safety guidelines.

The following is an overview of the work carried out when inspecting and cleaning a water tank.

  • An engineer will visit your site and conduct a survey to identify any additional health and safety precautions required.
  • Isolation of the cold water storage tank and any pump sets.
  • Fully drain the tank and undertake a physical clean to impeccable aesthetic standards.
  • Manually scrape clean the internal surface to remove debris, dirt, sediment. At this stage, any signs of damage, corrosion, scale, flaking, black spotting, and deficiencies (e.g. missing rodent screens, cross-flow vents etc) are noted.
  • Chemical cleaning using silver-based hydrogen peroxide – the use of this chemical halves the volume of water needed to be ‘dumped’ than using conventional methods.
  • Use of alternative chemicals such as chlorine where applicable.
  • Where required, full system disinfection including all assets and pipework, measuring chemical levels at every outlet to ensure successful disinfection.
  • Tests carried out for TVC, E.Coli, coliform and Legionella by an INAB accredited laboratory (see Microbiological sampling).
  • Issuance of disinfection certificate and sample results for your logbook.

Keep Your Water Systems Compliant

Your water tanks need to be in optimal condition to ensure legionella compliance, so it is vital that they are periodically inspected, cleaned and disinfected.

Over 20 years of experience in the field has presented our engineers with a wide range of site issues, so you can be reassured we will recommend the most effective solution for your needs.

We are experts in legionella control and take immense pride in using our knowledge to deliver excellent results to our clients. We have the necessary expertise and training to carry out any work easily with minimum disruption to our business.    

Our services cover all types of tanks from routine domestic attic tanks to large cold storage and sectional tanks. We can perform both water tank inspections and tank cleaning services as part of our services to prevent legionella growth.

If you have questions about Legionella control in cold water storage tanks, we can help! Contact our team to know how we can help you.