FAQ: Legionella risk assessments

Could I incorporate a water risk assessment within a normal general H&S risk assessment?

The simple answer to this question is “yes”, a water (legionella) risk assessment can form part of the risk assessment, as required by the MHSW and COSHH Regulations.

However, the water risk assessment has to be suitable and sufficient to cover the specific measures associated with Legionella, which are outlined in ACoP L8 (Control of Legionella Bacteria in Water Systems), but briefly should identify:

  • Suitable conditions for Legionella growth, eg. water temperature of 25 to 45oC.
  • Means of dissemination eg. Showers, as the disease is contracted by the inhalation of legionella contaminated water droplets.
  • Presence and nature of the people of exposed.  Older and infirm people are more prone to contracting Legionnaires disease.

In addition, a water risk assessment typically includes the schematic drawings of the water systems present, asset register, measures to control the risk, monitoring programs etc.

Legionella risk assessments should be carried out at least every two years or when there is a significant change / usage of the water system, and should be undertaken for all commercial buildings, which contain a water system, not just buildings where cooling towers are present.

In all these instances relevant training will need to be detailed for those appointed when using these systems. The level of training will be dependent on the system and the risk of outbreak, however it is good practice to provide employees with toolbox talks to understand the potential hazards associated.

In most organisations, as a result, these assessments are often compiled by individuals who are specialists within this field. In turn organisations often choose to compile specific risk assessments in line with the overall H&S policy. It is also important to state that the person who is assigned this task must be competent; have sufficient experience, expertise and training with the systems in question.