Legionellosis is a collective term for diseases caused by legionella bacteria including the most serious Legionnaires' disease, as well as the similar but less serious conditions of Pontiac fever and Lochgoilhead fever. Legionnaires' disease is a potentially fatal form of pneumonia and everyone is susceptible to infection. The risk increases with age but some people are at higher risk including:

• people over 45 years of age
• smokers and heavy drinkers
• people suffering from chronic respiratory or kidney disease
• diabetes, lung and heart disease
• anyone with an impaired immune system

Legionella bacteria are widespread in natural water systems, e.g. rivers and ponds. However, the conditions are rarely right for people to catch the disease from these sources. Outbreaks of the illness occur from exposure to legionella growing in purpose-built systems where water is maintained at a temperature high enough to encourage growth, e.g. cooling towers, evaporative condensers, hot and cold water systems and spa pools used in all sorts of premises (work and domestic).

You can get Legionnaires' disease if you breathe in tiny droplets of water containing bacteria that causes the infection. It's usually caught in places like hotels, hospitals or offices where the bacteria have got into the water supply. It's less common to catch it at home. Many cases of Legionnaires disease in the UK are associated with foreign travel.

You can get Legionnaires' disease from things like:

• air conditioning systems
• humidifiers
• spa pools and hot tubs
• taps and showers that are not used often

You cannot usually get it from:

• drinking water that contains the bacteria
• other people with the infection
• places like ponds, lakes and rivers

• a cough
• difficulty breathing
• chest pain
• a high temperature
• flu-like symptoms

If you believe that you maybe suffering from Legionnaire's disease you should seek urgent medical assistance.

If you are an employer, or someone in control of premises, including landlords, you must understand the health risks associated with legionella. This section can help you to control any risks.

As an employer, or a person in control of the premises, you are responsible for health and safety and need to take the right precautions to reduce the risks of exposure to legionella. You must understand how to:

• identify and assess sources of risk
• manage any risks
• prevent or control any risks
• keep and maintain the correct records
• carry out any other duties you may have

The following resources will be helpful:

• Legionnaires disease - a brief guide for duty holders
• Legionnaires disease - the control of legionella bacteria in water systems
• Evaporative cooling systems
• Hot and cold water systems
• Spa pools
• Other risk systems

It is likely that for complex system you will need to appoint a competent person to help you. The Legionella Control Association can help you find a competent contractor.

A person who has control of a non-domestic premises where there is a notifiable device (cooling tower or evaporative condenser which passes water through a stream of air) must notify the Council in writing, unless the device:

• contains no water that is exposed to air
• has its water supply disconnected
• has its electrical supply disconnected

Any changes to the notified details must be brought to the attention of the Council, as must details of cease of use.

To Notify the Council of:

• A New cooling tower or Evaporative Condenser,
• The change in the details of the person in control, or
• the decommissioning of a cooling tower or evaporative condenser

Please use our Cooling Towers Form

Register of cooling towers and evaporative condensers (PDF, 26KB)

Storage tanks

Ensure incoming and stored water remains at a temperature of less than 20 °C, e.g. if necessary site storage tank in a cool place and provide insulation.

Testing a cold water storage tank

Sentinel outlets

Check water temperature at sentinel outlets on monthly basis.

• Test a cold water sentinel outlet
• Testing a hot water sentinel outlet

Hot water pipes

Check flow and return temperatures at calorifiers.

Testing outgoing water is at least 60°C

Sampling Videos

Sampling Techniques for Legionella Examinations