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COVID-19 UK: Safety, Health and Environment Regulatory - HSE guidance on managing legionella risks

  • 1 June 2020 1 June 2020
  • UK & Europe

  • Coronavirus

During the unprecedented situation resulting from the Covid-19 crisis, many premises have faced complete closure or reduced occupancy. With businesses having to turn their mind to new and sometimes unexpected health and safety challenges, the Health and Safety Executive (HSE) has recently published guidance on managing legionella risks during the coronavirus outbreak.

COVID-19 UK: Safety, Health and Environment Regulatory - HSE guidance on managing legionella risks

In this article, we consider the increased risks of Legionnaires' disease during lockdown, the HSE guidance and the measures that need to be put in place to control those risks to ensure safe re-opening.

Lockdown risk factors

Legionnaires' disease is caused by the growth of legionella bacteria in water supplies that are not adequately managed. The disease manifests as a type of pneumonia causing individuals to become seriously ill.

Those must susceptible are over 50, smokers or have underlying health conditions. It has been estimated in Europe that Legionnaires' disease proves fatal in at least 10 per cent of people[1]. It therefore comes as no surprise that those who have been infected with the Covid-19 virus, or who are recovering and have a compromised respiratory system, are at increased risk of contracting Legionnaires' disease.

The risks of legionella bacteria growth during lockdown should be considered by all types of businesses where water is stored or used and where there is a means of creating and transmitting breathable water droplets (aerosols); this includes both hot and cold water systems.

Legionella bacteria are likely to grow in water systems where the temperature of the water in the system, or parts of the system, is between 25 degrees and 50 degrees. In addition, there is greater risk of bacteria growth where water is left to stagnate. Stagnation in water systems can also lead to degradation of water components resulting in by-products or mechanical deterioration from corrosion.

The increased risks associated with lockdown are obvious where buildings have closed and consequently shut down the water supply, or have restricted its use resulting in poor or no flow. The chartered Institute of Environmental Health advises "generally where water is left within a system without movement for more than a week then the risk of growth will increase"[2].

Control measures and re-opening safely

Employers, the self-employed and people in control of premises, such as landlords, have a legal duty to identify and control risks associated with legionella.

The HSE has produced helpful guidance[3] in respect of control measures to be taken during the lockdown and prior to re-opening.

  • Risk assessment - in the first instance you will need to identify and control risks associated with legionella. If there has been continued use of a water system during the lockdown period the existing measures should be maintained to prevent legionella growth. In circumstances where a building closed or there was reduced occupancy during lockdown, risk assessments should be reviewed and legionella risks managed in order to protect people when the water system is reinstated or returned to use.
  • Hot and cold water systems - flush them weekly to prevent water stagnation. If this is not possible work with your competent person or people to ensure systems are cleaned (if required) and disinfected before the building is occupied.
  • Cooling towers and evaporative condensers - there is an expectation operations should have been reviewed in advance and with existing plans in place to ensure continuation of safe systems of work during any shutdown. This includes ensuring that:
    • adequately trained personnel are available to carry out essential checks and monitoring; and
    • chemical supplies are maintained and dosed appropriately.

Speak to your water treatment company for help and if you need to stop operation of any systems.

If cooling towers and evaporative condensers are likely to be out of operation for:

  • Up to a month - isolate fans, but circulate biocidally-treated water around the system for at least an hour each week.
  • More than a month - drain down the systems and clean and disinfect them. Clean and disinfect the systems again before refilling and returning to operation.
  • Commercial spa pools and hot tubs - if commercial spa pools and hot tubs are:
    • Being used, you must maintain the existing control regimes.
    • Not being used, you should drain, clean and disinfect them. You should also clean and disinfect them before reinstatement.

Implications of non-compliance

It is foreseeable that there will be an increased risk of Legionnaire's disease post lockdown in circumstances where buildings have been shut or there has been a reduction in the use of the water supply.

If no action is taken to manage the risks associated with Legionnaires' disease, or actions that have been taken are proven to be ineffective, dutyholders could find themselves in breach of health and safety law. With the HSE's latest indication that it will "carry out work to check that appropriate measures are in place to protect workers from COVID-19", coupled with the inevitable enquiries in response to complaints from employees/members of the public, businesses who fail to take action could find themselves subject to enforcement notices, or worse, facing criminal prosecution and a hefty fine.

Most businesses will have already suffered considerable financial loss due to the pandemic and may face ongoing uncertainty for the future. Enforcement action taken by a regulator, coupled with the reputational implications for breaching health and safety law, would make an already difficult situation drastically worse.

If you would like to discuss any aspect of this article further, please get in touch with a member of our team at

Author: Karen Baumann, Senior Associate.

[1] The European Society of Clinical Microbiology and Infectious Diseases (ESCMID) Study Group for Legionella Infections (ESGLI); Guidance for managing Legionella in building water systems during the Covid-19 pandemic.

[2] The Chartered Institute of Environmental Health Guidance; Legionella risks during the lockdown and reopening safely.



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