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Legionella FAQs

Monitoring Legionella Risk Assessments Resullts On Office Computer

What is Legionnaires' Disease?

Legionnaires’ disease is a potentially fatal pneumonia caused by legionella bacteria. Infection is caused by breathing in small droplets of water contaminated by the bacteria.

Who can catch Legionnaires' disease?

Everyone is potentially susceptible to infection but some people are at higher risk e.g. those over 45 years of age, smokers and heavy drinkers, those suffering from chronic respiratory or kidney disease, and people whose immune system is impaired.

Where is legionella found?

Legionella bacteria can be found in natural watercourses such as rivers and ponds. Since legionella is widespread in the natural environment, it may contaminate and grow in man-made water systems such as cooling towers and hot and cold water services.

The bacteria thrive at temperatures between 20 and 45 degrees, particularly if there is a supply of nutrients such as rust, sludge, scale, algae and other bacteria.

How do I comply with latest HSE guidance?

The first thing to do is a Legionella Risk Assessment, to consider the risks from legionella that may affect your staff or members of the public, and then take suitable precautions to control and prevent the risk.

What can be used to control legionella bacteria?

Temperature is usually used in hot and cold water systems, by keeping hot water at above 60 degrees and ensuring it is above 50 degrees at the outlets. Cold water should be kept at below 20 degrees.

There are other methods which can be used if temperature is not an option, such as copper/silver ionisation and chlorine dioxide.

Cooling towers / systems are often treated with biocides. There are other treatment strategies available such as ultra violet (UV) irradiation.

Do I need to take Legionella samples?

This depends on the risk assessment and control methods being used. In some circumstances it will be required, however it needs to be done at a UKAS accredited laboratory and will require specialist help. Dantek can provide advice on sample frequency and locations, and what to do if Legionella is detected.

Where can I get more information?

  • Call Dantek for expert advice and support.
  • Order a copy of the Approved Code of Practice and guidance Legionnaires’ Disease: The control of legionella bacteria in water systems L8.
  • Contact the Water Management Society (WMS):

What information do I need to get a quote for a risk assessment?

Often a site visit by one of our sales team is the best way to establish exactly how much a risk assessment will cost. However; we are often able to provide a guide price if you know roughly the size and type of building. For example how many floors, what it is used for, whether there are any cold water storage tanks, number of calorifiers and if there are any cooling towers. One of our sales team would be happy to talk through on the phone any requirements and enquiries.

What do Landlords need to do about Legionella control?

The law clearly states if you are a Landlord and rent out your property then you have a duty under Health and Safety Law to consider the risk posed by Legionella bacteria. The ACoP L8 (3rd edition) also states Landlords must assess the risk from exposure to legionella to their tennants.

In most cases the risk assessment is simple and straight forward, however for more complex systems or if the Landlord is not able / competent to carry out the assessment they can use a specialist Water Treatment Company like Dantek, to carry out the legionella risk assessments and advise on any actions required.

Do make contact if you are a Landlord and are unsure about what to do about Legionella control or if you would just like some further advice about the prevention and contol of legionnaires disease.

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