Legionnaires’ disease is a potentially fatal form of pneumonia which affects the lungs.

The risk of infection increases with age but some people are at higher risk including:

  • people over 45 years of age
  • smokers and heavy drinkers
  • people suffering from chronic respiratory or kidney disease, diabetes, lung or heart disease
  • anyone with an impaired immune system.

Where does it come from?

The bacteria associated with Legionnaires’ disease are common in natural water sources such as rivers, lakes and reservoirs, but usually in low numbers.

They may also be found in purpose built water systems such as domestic hot and cold water systems.

If conditions are favourable, the bacteria may grow increasing the risks of Legionnaires’ disease.

Outbreaks of the illness occur from exposure to Legionella growing in purpose built systems where water is maintained at a temperature high enough to encourage growth.

How do people get it?

People contract Legionnaires’ disease by inhaling small droplets of water (aerosols) suspended in the air containing the bacteria.

Certain conditions increase the risk from Legionella. For example:

  • the water temperature in all or some parts of the system is between 20°C and 45°C
  • breathable water droplets can be created and dispersed, for example aerosol created by shower heads, water outlets, spa baths
  • water is stored and/or re-circulated
  • there are deposits that can support bacterial growth, for example rust, sludge, scale and organic matter
  • outlets are used infrequently
  • the system contains dead ends or unused pipe work.

Reducing the risk of Legionella

The risk of Legionella causing illness in small domestic properties is exceedingly low.

Possibly the biggest risk is when you have been away from the property for more than a week or there are additional taps, showers or toilets that are not used daily.

Good practice in this situation is simply:

  • run all the taps and shower heads for at least 60 seconds every week to make sure you don’t have water standing still in pipes
  • showers heads and taps should be cleaned of scale and debris every three to six months
  • keep the hot water on your boiler system at a temperature of minimum 50°C to 60°C
  • flush the toilet twice weekly with the lid down to circulate fresh water through the system and empty the cistern
  • report any problems you may have with your hot water system as soon as possible
  • disconnect and empty any hosepipes when not in use
  • if you have a water butt, items that create spray should not be attached to them.


Ensuring your safety

Owners and managers of private rented property have a legal duty of care to ensure that their tenants and visitors can use the property safely.
The Health & Safety Executive is the government body responsible for water hygiene and Legionnaires’ disease. Further advice and information can be viewed on their website. www.hse.gov.uk/legionnaires

Report an error on this page

Report Error

Please fill out the form with details of the error.

  • This field is for validation purposes and should be left unchanged.