Legionella Disease A Block Management Guide

The law is clear that if you are a Landlord, Freeholder or Block Manager you will need to ensure that the properties you manage are safe and free from health hazards (HSE)

Duties under the Health and Safety at Work etc Act 1974 (HASWA) extend to risks from Legionella bacteria and the Control of Substances Hazardous to Health Regulations 2002 (COSHH) provide a framework of actions designed to assess, prevent or control the risk from bacteria like Legionella

For practical guidance on how to manage and control the risks in water systems, we suggest reviewing this document initially “Approved Code of Practice (ACOP): Legionnaires’ disease: The control of Legionella bacteria in water systems”

Here are important facts about Legionella and Legionnaire’s disease;

  1. Legionnaire’s disease is a potentially fatal form of Pneumonia caused by Legionella Bacteria.
  2. Legionnaires disease is contracted through the inhalation of small droplets of water (aerosols) suspended in the air; most commonly through showers, air-conditioning units, taps, sprinklers and other outlets that cause an aerosol.
  3. The symptoms of Legionnaires disease include: high temperature, cough, muscle pains, headache, pneumonia, diarrhoea, and signs of mental confusion. As a result of these symptoms being so similar to a severe flu, many cases of legionella can go undetected or missed diagnosed.
  4. Although legionella is a potentially fatal form of pneumonia and everyone is susceptible to infection, the risk from the disease increases for people over 45, smokers and heavy drinkers, people suffering from respiratory disorders, diabetes, lung and heart disease or anyone with an impaired immune system.
  5. This bacteria growth in certain conditions and with the right environmental conditions, any water system could be a source of growth for Legionella.

Legionella bacteria thrives if:

  • temperatures are between 20°C and 45°C (The human body temperature is 36.1-37.2 therefore ideal for legionella bacteria growth)


  • there are sources of nutrients such as rust, scale or organic matter


  • there is no or little water flow therefore the water stagnates


6. As a Block Manager, or someone in control of the premises (i.e. Landlord or Freeholder), you are responsible for Health and Safety and therefore need to take steps to reduce the risks of Legionella. These steps are;

Identify and Assess the Risk

This is 1st step to managing the risk of Legionella. It is a legal requirement to assess the potential risk of Legionella exposure in a property or block, and also to control this risk

This is achieved through a Legionella Risk Assessment, which must be conducted by a competent person, who has sufficient knowledge and experience in order to complete this assessment correctly and thoroughly

Manage the Identified Risk

Once the risk of Legionella in the property has been identified and assessed, the next step is to begin the process of managing that risk

The Health & Safety Executives ACOP L8 requires that the Duty Holder appoint a Legionella ‘Responsible Person’ to take day-to-day responsibility for controlling Legionella bacteria and Legionnaires’ disease

This means any action points from a risk assessment as assessed and resolved, ensuring appropriate contractors are appointed to maintain the system and completing routine monitoring of the system as necessary

Prevent and Control

The spread of Legionnaire’s disease is very much preventable and the best way to do this is reduce the amount of stored water

The HSE describe a typical ‘low risk’ example as a small domestic-type water system, where daily water usage is sufficient to turn over the entire system; where cold water is directly from a mains supply (therefore no storage cold water tank) and where hot water is fed from instantaneous heaters, such as a combination gas fired boiler. However in many blocks there are large cold water tanks that collect the main fed water and then pump it up to individual apartments when required, these are water tanks must therefore be carefully monitored and maintained. One easy way to monitor these tanks is completing a routine temperature test to ensure the water temperature does not go above 20 degrees

Indeed, the best approach to prevent the risk is by eliminating the conditions that allow Legionella bacteria to grow and disperse, therefore for example, this means removing any identified “dead legs” where water can stagnate

Keep Records

The final important step to complete is ensuring along with a risk assessment, records of routine monitoring and appropriate testing are maintained to illustrate evidence of the actions taken to eliminate or reduce the risk

A logbook similar to the type used for routine fire alarm testing, is a good method of capturing this testing information


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