Legionella & Fire Fighting Sprinkler Systems


Legionella is a bacterium that is commonly found in natural water sources such as lakes, reservoirs and rivers, usually in small concentrations that pose no threat to public health.

However, once this water enters man-made water systems such as fire fighting sprinkler systems, under certain environmental conditions there is a risk that any legionella bacteria that are present in the water may proliferate, increasing the risks associated with Legionnaires’ disease.

Health & Safety Executive

The UK’s Health & Safety Executive (HSE), in their paper ‘A revised programme of interventions for the control of legionella risks in workplaces’ classify artificial water systems into three risk groups, with level 1 being the highest risk. Fire fighting sprinkler systems fall into risk category level 3. This is for systems that may use water for cooling and misting and commonly allow water to stagnate and generate aerosols.

Fire fighting sprinkler systems do present a legionella risk and should be incorporated into any legionella monitoring and control programme that you currently have in place...

Assessing & Managing Legionella Risks in Fire Sprinklers

There are a number of important guides and regulatory documents that should be referred to when managing the risk of legionella in fire sprinkler systems:

  • The HSE’s Approved Code of Practice (ACOP) L8: Legionnaires’ disease: The control of Legionella bacteria in water systems - This code of practice covers the management and control of legionella risks in water systems.
  • The HSE’s technical guidance document HSG274 Part 3 – The control of legionella in other risk systems – This useful document gives practical guidance for controlling legionella risks in “other” water systems (i.e. not hot and cold water or cooling water systems).
  • The Control of Substances Hazardous to Health Regulations 2002 (COSHH) - This document provides a framework of actions designed to assess, prevent or control the risk from bacteria like legionella and take suitable precautions.
  • The Management of Health and Safety at Work Regulations (MHSWR) - This provides a broad framework for controlling health and safety at work
  • Health and Safety at Work etc. Act 1974 (HSWA) - Your duties as an employer to manage risks in the workplace.

Catching Legionnaires’ Disease from Fire Sprinklers

For human infection of Legionnaires’ disease to occur from fire fighting sprinklers, any legionella bacteria present in the sprinkler system water would have to do three things:

1.    Grow to a level where they are infectious - There is a good chance that legionella will be present in most water systems. However, usually they will be present in small enough numbers not to pose any threat to human health. What has to be ascertained however, is whether conditions in the fire sprinklers could support the growth of legionella populations. Whilst generally the temperature in fire sprinkler systems will remain low enough as not to support the growth of legionella bacteria, it may contain distribution pipework that may become warmer. Other factors to consider are that most sprinkler systems contain stagnant water and have some degree of agitation in storage tanks during regular pump flow tests. Generally, fire sprinkler systems will not normally support the growth of legionella but there is a risk, especially due to poor maintenance of the systems.

2.    Be present in an aerosol - Droplet formation and dispersal can occur in three main situations:

i.      Faulty plumbing
ii.     During the cleaning or maintenance of pumps/system
iii.    The operation of sprinklers

Generally the droplets formed by sprinkler systems are too large, but there remains the possibility that small enough droplets could be formed from larger ones breaking up or evaporating.

3.    Be inhaled by an individual susceptible to infection - The risk of anyone being infected during the operation of sprinkler systems is reasonably low due to the fact that when a fire sprinkler system is triggered, occupiers of the building will have been evacuated and only protected people (e.g. firefighters) will be in the vicinity. However, it is important to note that there remains a risk to those involved in the resting, maintenance and cleaning of such sprinkler systems.

Proactively Managing the Risk

Fire fighting sprinkler systems should be incorporated into any legionella monitoring and control programme that you currently have in place. You should:

  • Prepare a written scheme of control to prevent, monitor and control the risks identified in the legionella risk assessment.
  • Identify, implement, manage and then monitor the precautions and controls you have put into place
  • Appoint a competent person or company to manage the risk.
  • Keep detailed records of all of the above.

How Legionella Control International can help?

With fire sprinkler systems representing a legionella risk that could cause a potentially lethal outbreak of Legionnaires’ disease and result in prosecution, effectively managing the risks involved is vital. As experts in the risk management of Legionnaires' disease, legionella and other water-borne pathogens, we can help devise comprehensive risk management programmes dealing with water safety issues in industrial, commercial, healthcare and institutional facilities. Our services include risk assessments, legionella testing and much more.

To find out how to safeguard your facilities and ensure compliance with the legislation please contact us on 0161 877 0586 (Manchester) or 0203 637 47 48 (London).

Unit B Badex Building
Westbrook Park
Manchester M17 1AY
United Kingdom

Tel: +44 (0) 330 223 36 86
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Kemp House
152 City Road
London EC1V 2NX
United Kingdom

Tel: +44 (0) 203 637 47 48
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Legionella Control International
Unit B Badex Building
Westbrook Park
Manchester M17 1AY
United Kingdom

Manchester: +44 (0) 161 877 05 86
London: +44 (0) 203 637 47 48
Email: info@legionellacontrol.com

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