Legionnaires’ disease is a type of pneumonia. It can only be contracted by the deep inhalation of tiny water droplets, called aerosols, which are contaminated with legionella bacteria.

This disease primarily affects people who have increased susceptibility due to predisposing factors, such as age (50 years +) smoking, existing illnesses, etc. Men are more susceptible than women. Legionella infected aerosols can be produced from water systems which create spray, such as showers, cooling towers, spray taps, decorative fountains and Jacuzzis.

On average there are 200-250 reported cases of Legionnaires’ disease in the U.K. each year.


  1. The first identified outbreak was in 1976 among people attending the Pennsylvania State Convention of the American Legion, where 221 people were infected. 34 died. An apparently new bacterium was isolated from lung specimens.
  2. Retrospective examination of stored specimens from previously unsolved outbreaks showed some were also caused by the bacterium now known as Legionella pneumophila. The disease was therefore not new but newly recognised in 1976.
  3. Organisms are found widespread in rivers, lochs, mud, soil and man made water systems.
  4. To date 37 Species recognised.
  5. Lp Sero group 1 is most associated with Legionnaires Disease in UK.
  6. Legionella bacteria growth is favoured in the temperature range of 20 – 45ºC


All employers with 5 or more employees must commission a Legionella risk assessment on their water systems every 2 years or sooner if significant changes are made to existing systems. Failure to comply with the legal requirements surrounding Legionella can result in prosecution. If the Health and Safety at Work Act 1974 applies to your business premises, then you are required by law to commission a legionella risk assessment on its hot and cold water systems.

For information on your legal obligations surrounding your hot and cold water systems the following legislation outlines what is required:

We provide appropriate Legionella risk assessments for a wide range of businesses including:-

A Risk Assessment is an important step in protecting your staff and your business, as well as complying with the law.

For a full risk assessment, simply get in touch with our team and we'll be more than happy to help!