Legionella Risk Assessment Procedure

The aim of a Legionella Risk Assessment should be to assess and record the extent, condition, design and management of all water systems within a property. It should assess and describe the risk of bacterial contamination by Legionella species, the potential for the bacteria to multiply and the potential for this to infect people with Legionnaire's disease.

The risk assessment should allow the site management to instigate remedial actions to decrease any perceived immediate risk and to implement a Legionella risk control programme to manage the risks long term. The Legionella assessment should include not only the physical water system but should also include the management structure, current control systems and execution of these control mechanisms. Without adequate management a Legionella control programme will always fail.

When undertaking a Legionella risk assessment all recommendations should be made with the site's specific requirements in mind, taking into consideration such things as occupancy and usage. It should also take account of such things as budgets and manpower so as to devise realistic options that the site will be able to implement.

When presenting the report it should be done in such a way as to make understanding of the requirements easy. It should provide detailed remedial actions with prioritised risk ratings to enable site to remedy higher risk items first. It should also provide details of ongoing control measures such as temperature monitoring. These should be site specific and should not include generic statements copied from guidance documents. All assets such as storage tanks and calorifiers (water heaters) should be listed as well as providing a detailed list of all outlets. Photographs should be provided to show assets and to highlight any areas of concern or specific problems.

Detailed schematic diagrams should be produced for the systems surveyed and should include all major distribution pipe work, associated plant and outlets. Whilst schemcatic diagrams will be based on a non-intrusive basis it is important to trace as much pipework as possible to ensure such problems as dead legs are not present. This is particularly important in older buildings which may have undergone a number of usage changes, resulting in removal of existing outlets.

A Legionella risk assessment should be truly bespoke and should include the following information:

  • Design and physical condition of hot and cold water systems, tanks, water heaters, thermostatic mixing valves (TMVs), air conditioning and all other systems capable of posing a risk
  • Aerosol generation capability of outlets and water systems
  • Storage and distribution temperatures
  • Any areas of stagnation or dead-legs
  • Biological analysis results
  • Risk of exposure posed by each system
  • Detailed system schematics
  • Remedial works recommendations
  • Any chemical treatment requirements
  • Management regime recommendations

    • Call us now on 0845 2603310 to discuss your requirements with a trained Legionella Risk Assessor

    LCA Logo CHAS Logo Constructionline Logo ISO Logo