Legionnaires’ disease and returning to work

Shop door being opened

Returning to the workplace? Have you thought about Legionnaires’ disease?

Following Government announcements many businesses are re-opening their premises following the Covid-19 lock-down. Many offices, shops, factories, leisure centres, salons etc. have been completely uninhabited for several months.  

As businesses begin the transition back to the workplace, there are many considerations to make to ensure peoples’ safety.

One of the potentially less obvious risk is Legionnaires’ disease. Legionnaires’ disease is a respiratory disease caused by inhaling droplets of water that contain legionella bacteria. With the right conditions any water system could be a hub for legionella bacteria growth.

Your workplace is at risk of legionella if they have a purpose built water system such as:

  • Air conditioning units
  • Hot and cold water system
  • Decorative fountains
  • Cooling Tower or condenser
  • Emergency showers
  • Spa pools


Identifying the risk

All systems like the above should be assessed to see if they pose a risk however some systems will be more likely to carry the bacteria.  

Environments that have a higher exposure include:

  • Where the water temperature is between 20-45 degrees Celsius in all or some parts of the system
  • Where water is re-circulated or stored as part of the system.
  • Where there are sources of nutrients in the equipment such as scale, sludge, rust, biofilms or organic matter.

Additionally, certain scenarios will pose a greater risk to people:

  • If it is possible for water droplets to be produced and if they can then be dispersed, e.g. showers or aerosols from cooling towers.
  • If it is possible for any visitors, employees, residents etc. to be exposed to any contaminated water droplets


Managing the risk

Once the potential areas of risk have been identified a person must be appointed to help meet your health and safety duties and control the risks of being exposed to Legionnaires’ disease. This role may include managing any contractors you employ to carry out the water treatment work if necessary.

If you have identified a risk you are unable to prevent, you should implement a course of action that will help with managing the risk by introducing control measures, such as:

  • Properly controlling the release of water spray
  • Keeping the system and the water in it clean
  • Treating the water to limit the growth of legionella or control the growth if that is not possible
  • Monitoring any measures implemented
  • Keeping a record of any actions taken so they can be properly monitored.

The HSE has provided full guidance on identifying, managing and preventing risk of Legionnaires’ disease. Please visit the HSE website for more information.


Source: HSE, Are there Legionella risks in my workplace? https://www.hse.gov.uk/legionnaires/workplace-risks.htm