Legionella Bacteria

What is Legionella Bacteria?

The Health and Safety Executive defines legionella as a collective term for a disease caused by legionella bacteria, that includes the most serious, legionnaires disease, a potentially fatal form of pneumonia. All members of the population are susceptible to this disease, however some groups
are more vulnerable,

these include :-

  • The elderly
  • Smokers and drinkers
  • People suffering from respiratory or kidney diseases
  • Diabetes
  • Lung and heart diseases
  • Weak immune systems

What is the source of Legionella Bacteria?

Legionella is found in natural surroundings including rivers, lakes and man made water features such as fish ponds. Most natural sources are not associated with legionnaires disease out breaks. Legionnaires disease is more closely associated with stored water systems associated with the built environment, these include hot and cold water storage systems and piping associated with the supply to outlets.

Outbreaks of the illness occur from exposure to legionella growing in purpose built systems, where water is stored at temperatures that permit the bacteria to flourish. These will include both hot and cold water systems, evaporative condensers, cooling towers as well water left in undrained hosepipes during the summer months, when elevated temperatures are experienced.

How is Legionella Bacteria contracted?

Legionnaires disease is passed by inhaling infected aerosols, which are small water droplets, suspended in air containing legionella bacteria. This is typically associated with poorly maintained cooling towers, but is also experienced in showers and spa pools. The built in environment is a significant factor in elevating the risk of legionella and its management is essential for managing the risk. The risk assessment includes water temperatures, legionella grows between 20°C and 45°C. It is essential that cold water is stored below 20°C and hot water at temperatures reaching at least 50°C.

Other sources of legionella are nutrients, found within both hot and cold water systems.

These include :-

  • Biofilm
  • Rust
  • Sediment
  • Other organic mater including avian, insect and rodent presence.

Management of Legionella 

All premises subject to business or other economic activity are subject to Legionella Risk Assessment, which should be further managed by Legionella Awareness Management, between risk assessments. All management of such activities should be recorded.

Failure to manage such activities is a criminal offence, covered by Section 3 Health and Safety at Work Act 1974.

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