Safety and first aid

Minimising the risk of a Legionella infection at home

Legionella infection – or Legionnaires' disease – is a severe form of pneumonia caused by Legionella bacteria. The bacteria is found in damp or wet environments, ranging from damp gardening soils to spa baths.

Read more about the signs and symptoms of Legionnaires' disease and who is most at risk.

There are a few simple things you can do around the home to avoid or prevent conditions that allow Legionella to grow to high levels.

Using potting mixes and gardening soils

Legionella bacteria can be found in potting mixes, composts, mulches, soil conditioners and gardening soils. This includes bagged material and soils purchased in bulk form, such as a trailer load of mulch.

They can be harmful to your health if you do not take some simple precautions.

When handling these materials:

  • Always wear gloves.
  • Wear a face mask to help avoid inhaling aerosols.
  • Open bagged material with care to avoid inhaling airborne particles in the mix.
  • Keep the mix damp while in use.
  • Wash your hands thoroughly after use.
  • Store potting mix in a cool place, out of the sun.

Domestic evaporative air conditioners

Evaporative units used for home air conditioning are a potential source of Legionnaires' disease. Some simple steps should be followed to maintain your evaporative air conditioner.

Before summer:

  • Disconnect power to the unit.
  • Remove external weatherproof covers.
  • Remove filter pads, clean them thoroughly with a hose and replace with new filters if necessary.
  • Clean and scrub all waterways, including the bleed-off system and sump.
  • Close drains if required and fill with clean water.
  • Disinfect the unit with a biocide (a substance that can control the growth of harmful organisms) such as chlorine-based household bleach.

At the end of summer:

  • Disconnect power to the unit.
  • Loosen any sediment and slime with a brush.
  • Drain all water from the unit’s tank and pipes.
  • Clean the tank and pump with a cloth soaked with a chlorine-based household bleach then flush with clean water.
  • Remove filter pads, hose clean and allow to dry.
  • Dry the internal components, leave drains open and fit covers to exposed units if required.

Air conditioning firms can provide a cleaning and maintenance service.

With all evaporative coolers always make sure the water supply is clean and fresh.

Portable evaporative coolers

Portable evaporative units should be completely drained and cleaned at least once during hot weather, and left dry when not in use.

Refrigerated air conditioners

Units such as domestic refrigerated/reverse cycle integrated and split systems remove heat and moisture from the air without using water. They do not harbour Legionella bacteria.

Domestic hot water systems

  • Domestic plumbing systems must be installed and maintained correctly to ensure the risk of Legionella growth is minimised and to reduce the risk of scalding.
  • Regularly flush hot/warm water pipe lines (for example showers, taps) to prevent water stagnating.
  • Regularly clean shower heads.
  • Consult a plumber if you have any concerns.


  • Fountains can create aerosols by splashing water, and are a particular risk if the water is warm or heated intermittently by submerged lighting.
  • Regular draining, cleaning and disinfection is recommended.

Nebulisers and humidifiers

  • Nebuliser bowls should be rinsed after each use, and the entire chamber and mask washed daily in warm water and dishwashing liquid.
  • All components should be rinsed and allowed to air dry.
  • Nebuliser pumps should be serviced and filters changed regularly, in accordance with the manufacturer’s instructions.
  • Humidifiers should be emptied, cleaned in warm water and dishwashing liquid and rinsed each day.
  • All components should be allowed to air dry.
  • Only distilled water or water that has been boiled and allowed to cool should be used in humidification devices.

Spa baths

Regularly clean and disinfect your spa as per manufacturer’s recommendations to control the growth of Legionella bacteria.

Public Health

This publication is provided for education and information purposes only. It is not a substitute for professional medical care. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your healthcare professional. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified healthcare professional for a diagnosis and answers to their medical questions.

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