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Legionella Risk Assessment

Legionella Risk Assessment

A Legionella risk assessment is a site-specific document that details the findings of an examination of the entire water system within the property. The purpose is to identify if there are any parts of the system that might support or enable the growth of the Legionella bacteria and therefore present a risk to building users.

Contact Acorn today to arrange your personalised risk assessment.

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What does a Legionella Risk Assessment cover?

The assessment takes into account the following factors:

  • Water Temperature
  • Water Stagnation
  • Potential for Aerosol Formation
  • Heat Gain / Loss Potential
  • Condition of the Water
  • Condition of all water systems
  • The Susceptibility of persons exposed on site.

How often do I need a Legionella Risk Assessment?

(HSG 274 (part 2), page 53)The risk assessment should be reviewed regularly and whenever there is reason to believe the original assessment may no longer be valid, for example:

  • Where there have been changes to plant, the water system or its use
  • Where there have been changes to the use of the property
  • Where new information about risk or control measures have become available
  • Where temperature monitoring indicates that control measures are no longer effective



The risk assessment would include all hot and cold water services. All information would be recorded on audit forms and collated within a single document. This document will be supplied to the client in either PDF or physical folder format.

Temperature measurements would be completed, checked and evaluated. The following standards should be met:

  • Hot water stored at 60°C and above.
  • Hot water at outlets to be a minimum of 50°C within one minute of running
  • Cold water stored below 20°C
  • Cold water at outlets to be a minimum of 20°C within two minutes of running

A colour schematic drawing will be produced showing a layout of water systems within the property.

All areas requiring remedial action would be covered in the recommendations section of the report. A written quotation for these works will be made available to the client upon request.

How Can We Help?

Frequently Asked Questions

Yes, by managing systems where legionella is most likely found. Secondly, contacting a professional who can complete treatment on sources where the risk of legionella is high is also advised.

Legionnaires’ disease can be contracted when water droplets containing Legionella bacteria enter a person’s lungs.

There is currently no cap on fines for Legionella. However, examples show companies being fined nearly £2 million after failing a legionella test

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