Legionnaires’ disease

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Key facts

  • Legionella is classified as a 'hazardous substance' and you are required to undertake a risk assessment, and any subsequent remedial actions, in order to protect both your staff and customers.
  • If you have five or more employees, you need to record both what assessment and actions you undertook.

Note: the risk of Legionella bacteria breeding in a property’s water system increases significantly if the property remains unused for a prolonged period. Therefore, if your property was required to close due to COVID-19 restrictions, it is recommended that you either drain the water system or flush the system prior to reopening. Read the Gov.uk guidance on safe water systems for organisations, particulary when reopening after COVID-19 lockdown.

Legionnaires' disease is a potentially fatal form of pneumonia caused by Legionella bacteria. While these bacteria are common in natural water systems, they usually occur in numbers too small to cause health problems. However, in the right conditions these bacteria can multiply quickly and cause a significant health risk.

These conditions are where water is maintained between 20–45C, is stored or recirculated, where there is a source of nutrients in the water (including rust or scale) and where there are aerial water droplets. This means that water tanks, spas or hot tubs, air conditioning units and showers are the most common places for the bacteria to breed.

Legionella is classified as a 'hazardous substance' and, therefore, you are required to undertake a risk assessment, and any subsequent remedial actions, in order to protect both your staff and customers.

If you have five or more employees, you need to record both what assessment and what actions you undertook. While it is not a legal requirement to record the assessment and actions if you have fewer than five employees, it is always recommended that you do so in case you are challenged at a later date.

If you have self-catering property or a B&B with a normal residential water system, this risk assessment will be straight forward as the risk of Legionnaires’ Disease should not be high. A full specialist assessment is generally only needed if you have a large commercial property or you are uncertain of the property’s water system.

The main things to check for are:

  • make sure that any debris is not getting into the system (e.g. ensure any water tanks have a tight-fitting lid)
  • make sure that the Hot Water Cylinder is set on at least 60C
  • make sure there is no redundant pipework in which water could become stagnant
  • make sure showerheads are regularly cleaned and disinfected.

If you have machinery that contains water, such as air conditioning units or a spa/hot tub, then special attention needs to be made to ensure that this is regularly serviced and cleaned.

If you operate a property where the water system is not in regular use (e.g. a self-catering property that has long void periods or closes over winter) then additional precautions need to be undertaken to make sure that the water in the system does not stagnate. If your property is going to be vacant for a significant period, you should either drain or flush the system before the guests arrive.

Further information on Legionella and how to control it in water systems is available on the Health and Safety Executive website.