While COVID-19 is at the forefront of people’s minds, Legionella is one hazard that may be overlooked as people return to their workplaces.
Is Legionella lurking

The bacteria thrives in water that is left stagnant between temperatures of 20–45°C and with many premises left empty for some time it could increase the risk of an outbreak if water systems have not been used regularly or been properly maintained.

Legionnaires’ disease is a potentially fatal form of pneumonia, and those most at risk include the elderly, the very young, people with immunosuppressed systems and those with underlying respiratory conditions. So, any heightened risk of exposure needs to be taken seriously.

Areas most at risk of Legionella proliferation are hot and cold water systems, heating and air conditioning systems, spa pools, humidifiers and fire suppression systems. Control of Legionella within a water system is primarily tackled by temperature control together with a flushing regime.

Businesses who are reopening must have a Legionella control plan which should firstly identify areas of risk and nominate specific employees to carry out the plan.

The plan itself should include:

  • Flushing of outlets – with extended weekly flushing for premises with simple water systems (such as small shops and hairdressers)
  • Continued chemical dosing of evaporative cooling systems
  • Safely shutting down any water systems that cannot feasibly be controlled (in general, water systems should be left filled with water and not drained down)
  • Where wet cooling systems are being shut down, competent advice should be obtained prior to shut down

Would you like to talk?

If you have any concerns about your business or project please speak with your usual Gallagher representative. Alternatively, get in touch with the team using the below details:


  • Risk Management Team