When conducting the legionella risk assessment it is important to remember that a number of factors are required to create a risk of contracting Legionnaires’ disease or legionellosis. As a result it is extremely important to be able to demonstrate competence when assigning a risk rating to a water system.

The risk rating is derived by assessing the following:-

• The actual and potential risk for Legionella bacteria to colonise and proliferate in the system.
• The actual and potential for the Legionella to be disseminated in an aerosol form.
• The actual and potential for susceptible individuals to be exposed.

Further to this, the effectiveness of the control and preventative measures in place are assessed along with the effects of out of line situations on the risk levels. It is not considered essential to take water samples as part of the risk assessment.

However,

If water samples are tested for legionella and positive results are obtained this would increase the both the actual and potential risk and therefore the risk rating.

Aqua Legion UK do recommend that legionella samples be collected as part of the risk assessment. This will define the presence or absence of legionella as well as the type of legionella and numbers if present. This information can then be used to define the level of risk in more refined detail cost effectively.

However , you should be aware that Legionella positive results have been obtained from the most un-suspecting water systems in the past. Furthermore where surveys and inspections are none destructive, hidden pipework can often create areas for bacterial growth and contamination that cannot be detected through surveys alone.

However,

The absence of legionella bacteria should not lead to complacency!!  The potential for legionella growth may be significant even if legionella bacteria are not identified at the time of survey and therefore its absence may not necessarily reduce the risk rating.

Note: Legionella risk assessments which are based on a score rating should be treated with caution. Score systems can lead to gross misinterpretation of the risk rating assigned to a system. Far too often we see water systems being assigned a high risk due to the score system where the risk is actually low. A classic example of this is a low volume local water heater.

Aqua Legion UK use seven levels of risk – when rating systems.

1. Negligible Risk
2. Low Risk
3. Low Medium Risk
4. Medium Risk
5. Medium High Risk
6. High Risk
7. Immediate High Risk

The assignment of the risk rating is based on a complex combination of factors including our extensive competence, knowledge and real world practical experience.

by using Aqua Legion UK, you can be rest assured that each assessment is individually drafted to create a site and client specific service designed to achieve compliance to HSE guidance.

Would you like us to conduct your risk assessment? Contact us now!

Call 020 8555 3797