LEGIONELLA RISK ASSESSMENT
There are a lot of myths around legionella, but it should be noted that the bacteria is actually widespread in most natural water sources such as rivers and lakes. However, there are certain circumstances in which man-made water systems can provide the ideal breeding ground for the bacteria. A risk assessment is simply the process of ascertaining if these circumstances are present, resulting in health and safety risks for staff, residents and site visitors.
What is Legionella?
Legionnaires' disease is a potentially fatal form of pneumonia caused by the inhalation of small droplets of contaminated water containing Legionella. All man-made hot and cold water systems are likely to provide an environment where Legionella can grow. Where conditions are favourable (ie suitable growth temperature range; water droplets (aerosols) produced and dispersed; water stored and/or recirculated; some 'food' for the organism to grow such as rust, sludge, scale, biofilm etc) then the bacteria may multiply thus increasing the risk of exposure. It is a simple fact that the organism will colonise both large and small systems so both require risks to be managed effectively.
How do you get Legionnaires’ disease?
Legionnaires’ disease is contracted by inhaling small water droplets which can be suspended in the air known as aerosols. Aerosols containing the bacteria will pose a risk to susceptible individuals Infection however, is clearly linked to susceptibility. Highly susceptible individuals may get infected even at relatively low doses.
What are the symptoms?
Symptoms of Legionnaires’ disease, pontiac fever and loichgoilhead fever are all similar to the symptoms of very severe flu. Other Symptoms can be felt as: High temperature, feverishness and chills, Cough, Muscle pains, Headache, Pneumonia, Diarrhoea, Signs of mental confusion.
iFluids Engineering uses our expertise knowhow, experience andsupports each client by formulating and implementing water sampling strategies specific to each individual client and budget.
Figure: Factors affecting legionnaire’s Risk
Legionella Sampling Techniques
It is important to highlight that there is no statutory requirement to carry out routine legionella sampling to domestic water systems. However where water temperatures cannot be controlled within the desired range, routine legionella sampling can be a valuable tool in managing the risk of legionella.
Risk Assessment Report Content
Legionella risk assessment should include the following:
- A documented system overview, including pipework schematics and photographic evidence
- Testing of hot and cold water throughout the building at key points
- Water tank surveys
- Flow and stagnation tests
- Inspection for aerosol formation hazards
- Supply of digital thermometers, records and basic training to staff
Legionellosis: Risk management for building water systems. ANSI/ASHRAE standard 188–2015