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Preventing Legionella and Legionnaires’ disease

Legionnaires’ disease is a lung infection which you can get from inhaling droplets of water that contain the Legionella bacteria.

Legionnaires’ disease is uncommon, but it can be very serious and some people are at a higher risk, so it’s very important to ensure that all water supplies at work and at home are safe.

What causes Legionella bacteria to occur?

Legionella bacteria can grow if a water system:

  • is poorly managed
  • is not used for a week or more and the water is stagnant
  • has lime scale
  • has a water temperature between 20c and 50c.

How do you catch Legionnaires’ disease?

You can only catch Legionnaires disease if you breathe in tiny droplets of water that contain the Legionella bacteria.

It’s usually caught from water that has created an aerosol such as in an air conditioning system, humidifiers, spa pools and hot tubs, and from taps and showers that are not used often including a garden hose or from the aerosol created when washing the car windscreen. 

Legionnaires’ disease cannot be caught by drinking contaminated water. 

What are the symptoms?

Symptoms of Legionnaires’ disease include a high temperature, pneumonia, coughs, difficulty breathing and muscle pains.

The symptoms can be very severe and may require hospital treatment, including breathing assistance.

Who are the most at-risk groups?

Although anyone can become ill from exposure to Legionella, some groups are at higher risk, these include:

  • those over 45 years of age,
  • smokers
  • people suffering from chronic respiratory or kidney disease
  • those with an impaired immune system.

How to prevent Legionella in the workplace

Workplaces must have in place a suitable risk assessment for Legionella and appropriate controls in place to mitigate the risk.

Common controls include:

  • monitoring water temperatures to ensure the temperature at the outlet is below 20C or above 45C,
  • cleaning or treating water systems,
  • removing unused parts of water systems,
  • regularly running water through less used outlets
  • regularly reviewing your risk assessment and monitoring procedures.

More information about the requirements for businesses can be found on the Health and Safety Executive website.

How to prevent Legionella at home

It’s less common for Legionnaires to be contracted at home where water outlets are used each day.  

If you have outlets that you use less frequently, make sure you run these through regularly in a well-ventilated space to prevent water from being stagnant in the pipes too long. This includes running your showers when you come back from a summer holiday or your garden hose. You should also ensure water tanks are kept clean.

What should you do if you believe you’ve contracted legionnaires disease?

Legionnaires Disease is treated with antibiotics so, if you think you have it, you should contact your doctor as soon as possible. 

If you are confirmed as suffering from Legionnaires, your doctor will need to notify the UK Health Security Agency (UKHSA). The UKHSA will contact you to discuss any possible exposures you had – if you believe you know where you contracted the illness you should let the UKHSA know so that this can be investigated.