Legionella bacteria is commonly found in water sources. The bacteria multiplies in a temperature between 25 and 45 degrees Celsius when sufficient nutrients are available. The bacteria is dormant when the temperature falls short of 20 degrees and cannot survive above 60 degrees.

Nevertheless, it causes a disease named Legionnaires that is a deadly kind of pneumonia caused by inhaling water droplets contaminated by this bacteria. Any person can develop this disease but smokers, alcohol addicts, elderly people and those with conditions like cancer, kidney diseases and diabetes are more at risk.

Here are some of the places where Legionella bacteria can be commonly found:

  • Cooling towers,
  • Showers and faucets,
  • Hot tubs that are not cleaned regularly or drained after usage,
  • Hot water heaters and tanks,
  • Large plumbing systems and
  • Decorative water features such as fountains.

Prevention or cure?

Despite lots of research the healthcare industry has still not come up with any vaccines that can prevent Legionnaires’ disease. Instead, the key to preventing this condition is by ensuring that water systems and other potential sources are maintained in a good, clean condition in order to reduce the risk of growing and spreading Legionella bacteria.

Many experts recommend people operating water systems undertake routine Legionella training to increase awareness of the potential threats and how they can be avoided. Additionally, a full legionella risk assessment must be carried out and measures must be put into place to control the risk with maximum efficacy.

Using temperature controls is one of the ways in which Legionella can be controlled in water systems. Water services must be operated at temperatures that can prevent Legionella growth. Ideally, hot water storage cylinders must keep the temperature above 60 degrees Celsius and the cold water must be stored below 20 degrees Celsius.

A competent team of experts must be responsible for routine checks. Inspections must also be carried out on weekly basis and the systems must be managed and cleaned in accordance with the risk assessment. Outlets must be identified that are at a risk of developing this bacterium and must be managed accordingly, and in accordance with the assessment of risk.

Stagnant water further promotes the growth of Legionella and so must be avoided. Scenarios that encourage the stagnation of water in a system must be eliminated in order to halt the potential growth of this bacterium. Systems must be designed in order to keep the water source flowing correctly. Utilising materials of construction that do not encourage its growth is also important. Additional controls can also be incorporated in to the control programmes to allow those responsible to keep a track of the disease.

There are other legionella control methods as well that can be utilised to prevent the multiplication of the bacteria. These include copper and silver ionization and chemical biocide treatments. In order to effectively apply any of these methods, the overall treatment programme must focus on every aspect of the installation, and the monitoring and maintenance activities.


Legionella bacteria, since its identification in 1976 has been regularly popping-up in most countries throughout the world. This has generated a need for proper risk assessment in order to contain, or even eliminate the number of cases as much as possible. Even though water treatment experts can be consulted to help with control measures, there are some simple precautions homeowners can take for themselves. Simply search the Internet and you’ll find some great advice and DIY tips that can minimize the risks of exposure to this potentially deadly bacteria.

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