At the moment, lockdown restrictions remain in place across the UK to help minimise the coronavirus’s spread. As business owners, keeping your workforce safe from COVID-19 will be a priority. This may have resulted in some if not all of your staff having to work from home. Consequently, this has led to many premises in the UK being left either minimally or entirely unoccupied during the latest lockdown.
As already warned by both Public Health England (PHE) and the Health and Safety Executive (HSE), it’s a situation that could heighten the risk of legionella growth in a property’s water systems. When inhaled in water droplets, this bacteria can lead to the lung infection, Legionnaire’s disease, which – while uncommon – can pose a very serious health risk.

Why is the risk of legionella more prevalent during the COVID-19 pandemic?
The pandemic has already seen many commercial buildings across the UK – such as office premises, sports centres and hotels – closed or occupied to a lesser degree during periods of lockdown. The lack of use of such properties’ water systems during this time can lead to water stagnation which can increase the likelihood of the legionella bacteria getting into the water supply.
Even if, during the pandemic, you’ve had maintenance staff and engineers present to continue looking after the buildings for which you are a duty holder, periods of illness, isolation and travel restrictions may have hampered their ability to provide their pre-COVID-19 levels of service. This can be another factor increasing risk.
What safety controls should you consider?
It’s important to remember that even during times of COVID-19-related lockdown, organisations are still subject to Acts, regulations and guidance such as The Health and Safety at Work Etc Act 1974 and the Management of Health & Safety at Work Regulations 1999.
If, as a duty holder, you are implicated by your employees contracting Legionnaires’ disease from a contaminated water supply, you are unlikely to be exempt from prosecution simply because the outbreak may have arisen from COVID-19 precautions.
Therefore, it’s in your interest as a duty holder to take reasonably practicable steps to control the risk of legionella growth in your premises’ water systems at this time.
To this end, you may consult the HSE’s more detailed guidance on managing this risk during the pandemic, including the Approved Code of Practice and guidance for controlling legionella bacteria in water systems (L8 ACOP), and the technical documents HSG274 Part 1 and Part 2.
The main focus of your efforts to minimise the legionella risk on your premises is likely to be on its hot and cold water systems. In this area, you must tackle the issue of stagnation.
If your building is temporarily shut down (mothballed), then the HSG274 Part 2 provides guidance on the steps you should take. For example, you should not drain down pipework but should look to remove sources of heat and external thermal gain where possible. You should also lock off and advise potential users of your water systems that they have been taken out of use and that you have put in place a plan for recommissioning the water systems at a later date.
Meanwhile, controls that you might look to adopt if your premises are still partly in use include monitoring temperatures to ensure control of thermal gain in cold water as well as regularly flushing to simulate use. However, simply flushing once a week may not be enough to guard against the legionella risk.
What should you do when lockdown is lifted?
As we have touched on, it’s advisable to spend part of the preceding lockdown period devising a recommissioning plan for your premises’ water systems. The plan that you formulate should acknowledge that there is likely to be a greater risk of the legionella bacteria being present at this stage than at any time prior to the lockdown.
Even the smallest and simplest hot and cold water systems should, at the very least, be flushed through with fresh mains water prior to being brought back into action.
Larger buildings are likely to have more substantial and complex water systems, encompassing tanks, showers, calorifiers and the associated pipework. Suppose this describes the property for which you are a duty holder. In that case, you will probably need to arrange more extensive flushing, accompanied by cleaning and disinfection.
On completion of the disinfection process, you should also implement a sampling plan, encompassing – as a minimum – the premises’ cold water tanks, hot water units and sentinel points. No sooner than 48 hours after disinfection, water samples should be taken both pre and post-flush. These can then be analysed for legionella bacteria.
What should you do if your water sample tests positive for legionella bacteria?
Suppose your water sample tests show that legionella is present in your property’s water system. In that case, it is important not to panic – but also not to ignore this discovery, even if the count seems low.
As a broad rule of thumb, how you interpret your test result will depend on whether the given sample was taken before or after flushing. If you receive a positive pre-flush result but a negative post-flush one, this indicates local contamination. However, a negative pre-flush and positive post-flush result – or both results being positive – may suggest system contamination.
HSG274 Part 2 provides useful guidance on how to interpret water sample results. Regardless, if you have used a contractor to obtain the water samples, you should seek their advice on the next steps.
How best can you manage your legionella risk compliance in your properties?
As well as the measures mentioned above, one of the most important things you can do to manage the risk of legionella on your premises is to have a risk assessment carried out. This should be done once the building is ready to be reopened to your staff and/or the public.
Another key weapon in your legionella risk compliance armoury could be to utilise Legionella Risk Management Software, such as the Legionella Risk Management Module that makes up part of Assets & Compliance Managed Services UK’s Vision modular software. This module is fully configurable and adaptable to the different requirements of different sectors, as well as whether you are a duty holder for one or multiple properties.
The module provides a convenient overview of your entire legionella assessment for what may be an extensive property portfolio so will therefore guide you through the process. This, in turn, will allow you to review important findings and priorities easily and take the required action to control and manage the legionella risk in your buildings.
The Vision software even makes possible remote temperature checking that helps take some of the labour out of your legionella risk compliance efforts.
To find out more about the difference our Vision software could make to your property, compliance and risk management needs – including guarding against the risk of legionella – please call one of our specialist advisors on +44(0) 115 922 0600.