Preventing Legionella – Simple ways to keep this serious illness at bay

Legionnaire’s disease is a serious, often fatal, form of pneumonia that is caused by the Legionella bacteria. This microscopic nasty is everywhere and is usually not an issue, unless it is allowed to grow to a significant level outside the body.

Legionella bacteria like to grow in central heating units, air conditioning systems, and water pipes. When they are allowed to become a large enough colony, the bacteria can overwhelm the body’s defenses, particularly in the elderly, the young, and those with compromised immune systems.

A brief history

In 1976, convention-goers to an American Legion convention in Philadelphia, Pennsylvania, USA, began falling ill with a type of pneumonia. Within a week of the end of the convention, 130 people, mostly men, were hospitalised, and 25 died. They ranged in age from 39 to 85.

After that outbreak, Legionella pneumophila was discovered. Previously it had been considered a bacteria that only affected animals. Other significant outbreaks include Lochgoilhead fever in the UK (1988) and more recently in New Zealand, where the outbreak was traced to potting soil (2007).

Preventing Legionella

One of the most common places that Legionella grows is in water pipes. The bacteria loves warm moist environments, especially thriving at temperatures between 20 and 45℃. If Legionaella is allowed to develop in your facility’s waterworks it will create a colony that can quickly infect even the healthiest of people, and it will spread throughout your workforce like wildfire.

There are a few very simple things that you can do to prevent this devastating illness:

Don’t allow water to stand stagnant in pipes and cisterns for long periods.

  • Taps and showers should not be unused for long periods. If your facility closes for any period, such as over the summer holidays or Christmas, ensure all of the taps are run for several minutes before allowing people to use them.
  • Water cisterns should be covered to keep vermin and debris from falling in and contaminating the water.
  • Hot water should be above 50℃, preferably stored at 60℃.


If you have showers in your facility and are returning from holiday or haven’t used your shower in a while, run it for at least 2 minutes at the highest temperature.

If you have any at risk persons, such as elderly, or those with a compromised immune system, run the showers for 2 minutes every day before letting them under the water. It is a simple way to stay safe.



Hoteliers and others are required to comply with laws created to prevent Legionella from spreading. There are guidelines that have been written into law that everyone who provides residential accommodations must follow.  If you have staff that regularly travel for business, especially abroad, recommend that they run the water even longer. Flush the shower and the faucets before using the water for anything.   Ask the staff or landlord what steps they take to prevent Legionella. This is particularly important in resort areas where portions of hotels might be closed for extended periods.   When stepping into a hot tub bath, be sure that there is adequate chlorination and that the area is well-maintained.




One thought on “Preventing Legionella – Simple ways to keep this serious illness at bay

  1. Abi

    This is very interesting and highlights the importance of maintaining pipes and air con units, not just for financial issues but health issues (which is far more important). Thanks for the insight.


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