Legionnaires’ Disease is a respiratory disease, very similar to pneumonia, caused by the known as the Legionella bacteria. It is thankfully quite rare, since in 2016 there were only 345 cases in England and Wales – a much higher number of cases in America though, it has an approximately ten per cent mortality rate and steps must be taken to manage and control it.

If you are the responsible figure for managing Legionella risk in your building or office, or you own or manage a company or an organisation, then you should consider consulting with a professional Legionella consultant. Aside from consulting with an expert, here are a few facts that you must know about Legionnaires’ Disease and Legionella.


It’s everywhere

The Legionella bacterium can be present in any kind of water system and when the right conditions are provided, it can cause Legionnaires’ Disease.


Grows in warm water

Legionella can grow and harbour in any water system if the water is between twenty and forty-five degrees in any part of the system.


You can get infected by breathing it

You cannot contract Legionnaires’ Disease by drinking affected water; the water must be dispersed in the air as droplets. People may become infected by breathing in these droplets.


Certain places have a higher risk

This is why certain organisations with cooling towers, spa baths, sprinkler systems and showers carry the highest risk.


Are you part of the vulnerable group?

Around 75% of all reported instances are people over 50 years old, and around 70% are men. There are some risk factors that make you more vulnerable: excessive alcohol consumption, lung diseases, smoking, immunosuppression, renal diseases and chronic respiratory issues.

Anyone can potentially contract Legionnaires’ Disease but certain people are at a much higher risk. These include men and older people, smokers and heavy drinkers, people suffering from an existing respiratory condition and those with an impaired immune system


Thus, extra care is needed

This is why care homes and hospitals must be particularly vigilant


Incubation period

The disease has an incubation period between two and ten days. The symptoms initially include headaches, fever, loss of appetite, malaise and lethargy. Certain patients may report muscle pain, confusion and diarrhoea.


Keeping it under control

Legionella control involves four major principles: water must be kept hot – above fifty degrees; water must be kept cold – below twenty degrees; water must be kept clean; water must remain in movement.


Monitoring controls are required by law

The control and monitoring of Legionella is regulated through the Approved Code of Practice (ACoP) L8 passed by the Health & Safety at Work Act 1974. Every single organisation has a responsibility to comply with it.



While many companies outsource the management of Legionella, ultimately they have the final responsibility. This is why is still vital to understand the process and have good systems readily available.


Consequences and penalties

The penalties for not controlling the risk of Legionella adequately can go from a mere warning or fine all the way to corporate manslaughter charges, therefore this should be taken extremely seriously.



Just like with the new coronavirus, the vaccines against Legionella were a hot topic for a while. There has been progress when it comes to its management and prevention but nowadays we do not have a vaccine available against Legionellosis.

If you are unsure whether your knowledge of Legionella is insufficient or you would like to get practical tips for preventing the risk, you should consider learning more about Legionella risk assessment programs. We also offer free consultations so it’s well worth speaking to us, even if you think your systems are ok.