Legionella risks during the coronavirus outbreak

Updated 29/05/20

Legionnaires’ disease is a type of pneumonia which can cause serious illness in persons who are susceptible such as those over 50 years, smokers, and those with underlying health conditions.

The disease is caused by the growth of Legionella in building water systems which are not adequately managed. Closure of buildings, parts of buildings or their restricted use, can increase the risk for Legionella growth in water systems and associated equipment including evaporative air conditioning systems and other equipment if they are not managed adequately. *

If your building was closed or has reduced occupancy during the coronavirus (COVID-19) outbreak, water system stagnation can occur due to lack of use, increasing the risks of Legionnaires’ disease.

You should review your risk assessment and manage the legionella risks when you:

  • reinstate a water system or start using it again
  • restart some types of air conditioning units

If the water system is still used regularly, maintain the appropriate measures to prevent legionella growth. **

Questions to ask yourself

  • Has your building been closed or had reduced occupancy during the coronavirus outbreak? If so, water system stagnation can occur due to lack of use, increasing the risks of Legionnaires’ Disease.
  • Have you reviewed your Legionella risk assessment? You will have to document how you will protect staff, visitors and others from Legionella growth when your site is re-opened.
  • Have you checked your local Council’s and national guidelines about Legionella?
  • Do you need expert advice? Get advice from an experienced water treatment advisor, public health or environmental health authorities.
  • Was your water system drained before closing the premises during lockdown? The procedures you will need to follow to safely flush and restart your water system and air conditioning system varies depending on how your systems were managed during closure.  For information on safely flushing and restarting your water system, please download the full guidance on managing Legionella in building water systems created by the European Society of Clinical Microbiology and Infectious Diseases (ESGLI).
  • Do you need to get the water tested for Legionella? If so, this can take several weeks due to high demand.
  • If you are going to flush water systems that haven’t been used for several weeks, ensure you have the correct personal protective equipment to protect you from aerosols.


Really helpful guidance on managing Legionella in building water systems during the Covid-19 pandemic

UK government’s guidance on Legionnaires’ Disease during Covid-19 pandemic

Health and Safety Executive’s advice on Legionella risks during Covid-19 outbreak


Health and Safety Executive’s advice on Legionella risks in the workplace


Legionella control and mothballed buildings


* ESGLI Guidance for Managing Legionella in Building Water Systems during the Covid-19 Pandemic, 2020

** HSE advice on the risks of legionella during Covid-19 outbreak, 2020


Accessibility Options

The following options may make it easier for you to use this website

Change the contrast of colours and text

Change the size of the size of the text

Toggle the display of images