BrodexTrident Blog

What is legionella? A guide for facilities management companies

What-is-legionella-guide-for-facilities-management companies.png

In the UK, safeguarding against legionella bacteria is so serious that having a legionella risk assessment of your facilities is a legal requirement - and for good reason. Legionella’s pathogenic nature means that it can lead to harmful diseases, such as Pontiac fever, Lochgoilhead fever and the most serious Legionnaires’ disease.

This article explores the bacteria’s historical background, its microbiological structure and the laws surrounding it.


Legionella was first mass-detected in 1976 when an outbreak caused 34 deaths and sickened a further 221 people in Philadelphia. At this time, the disease was a mystery and the epidemic was of great concern in the US. It wasn’t until almost a year later, in 1977, that the causative bacterium was discovered and acquired its name as legionella.

Today, cases of legionella and its associated illnesses are closely monitored and reported. In the UK, the government tracks each instance of Legionnaires ’ disease and monthly reports containing qualitative and quantitative data are publicly made available online.

What is legionella?

Legionella is a pathogenic, rod-shaped bacterium and there are currently 50 different species so far identified. The bacteria itself does not transfer between one person to another, however, it is commonly found in soil and drinking water and is usually transmitted to humans via aerosols. The most common species of legionella is L.pneumophilia, which is responsible for many of the respiratory illnesses caused by the bacteria, including Legionnaires’ disease.

Legionella is widespread throughout nature, and is common to many rivers, lakes and soils in the environment. In synthetic and man-made systems, however, their numbers can spiral dangerously out of control. The bacteria tends to multiply most rapidly in temperatures between 20-45 °C.

Download the free legionella compliance and liabilities for FM companies guide  here >


The law states that all duty holders, including landlords and employers, must understand the danger that legionella poses to humans and control these risks. The Health and Safety at Work Act (1974) is particularly relevant, and duties under this act extend to controlling legionella. Responsible persons must:

  • identify any risks associated with legionella;
  • manage and monitor these risks;
  • prevent risks via specific measures like temperature control;
  • maintain records of assessments and methods.

Anyone that fails to control legionella risk and breaks health and safety legislation will face sentencing and potential imprisonment, not to mention damage to their reputation. The government has recently taken steps that make this process a lot more serious by introducing sentencing guidelines. The guidance states that persons can be prosecuted without anyone even being injured, if it is clear that risk is not being managed. Following the release of the guidelines in February 2016 there has been a sharp increase in fines being issued by courts, with 116 fines worth of at least £100,000.


Whilst it is the duty holder’s responsibility to abide by health and safety law and keep bacteria under check, if they feel they are not competent enough, they can pass the responsibility for legionella compliance to another more knowledgeable person or organisation.

The control of legionella involves a series of steps, usually starting with a risk assessment to determine the likelihood of legionella and any compromised areas within the building. Following this, control methods such as water chlorination, temperature control and disinfection of showers can be undertaken, if they are needed.

Keeping legionella at bay is not an easy task; it requires a thorough understanding of the bacteria and its accompanying risks, the control methods to safely prevent it and knowledge of how to abide by legislation. It’s therefore common practice to appoint a professional water treatment company who has the industry expertise as well as the equipment to keep you and your clients safe and compliant.

To help you achieve legionella compliance for your clients, we put together a comprehensive guide designed especially for FM companies and FM professionals. Donwload your free copy of the 'Legionella compliance and liabilities for FM companies' guide through the link below.

New Call-to-action


Recent Posts

Subscribe to Blog Updates