Legionella Temperatures – Understand What Temperature Kills Legionella

December 22nd, 2022

Last updated: January 18th, 2023

Legionella is a very serious risk within business premises and workplaces, and it is vital to be very cautious and diligent regarding legionella. Though the cases are rare and average out at around 300 per year in the UK, that is partially down to the stringent regulations that are in place. These should not be ignored.

Legionella causes Legionnaire’s disease, which can be fatal, and companies do not want to be found neglecting their responsibilities as this can result in fines of up to £20,000 or even imprisonment.

A Legionella risk assessment is a crucial part of your protection and is a legal responsibility of businesses. The risk assessment should be carried out by a “competent” person, but the definition of competence is vague. HSE describes this as “someone with the necessary skills, knowledge and experience to manage health and safety, including the control measures.”

If you are in any doubt, getting a third-party that you can trust to handle your Legionella control is a safer option, ensuring you always have professional advice and high standards on your premises, protecting staff, customers, and yourself.

One of the crucial parts of Legionella control is temperature, and this should always be factored into any risk assessments and considerations. In this guide, we’re looking at how temperature impacts Legionella bacteria and how it can thrive under certain scenarios, and die under others.

What Temperature Kills Legionella?

Some Legionella bacteria starts to die at 50 degrees, but this is not a total failsafe and there may be some of the bacteria that still survive through this temperature. This means that the hotter the temperature, the better the kill rate.

So, for example, if water is at around 50 degrees for two hours then the vast majority of the bacteria would die. However, raise the temperature to 60 degrees and it would take a matter of minutes for the same bacteria to die. At 70 degrees it is virtually instantaneous.

This means that all hot water supplies need to be stored at the lowest 60 degrees Celsius.

The “risk zone” for temperature starts again at 50 degrees but in healthcare environments such as care homes and hospitals, the risk zone is considered 55 degrees Celsius.

Hot water supplies are not the only way to store water. If you are storing cold water supplies then they must never go above the temperature of 20 degrees Celsius. Below this temperature the bacteria will not die, but they will become dormant and unlikely to cause any harm.

Understanding what temperature allows Legionella bacteria to thrive will show you why this is the case…

What Temperature Does Legionella Grow?

The most dangerous temperatures for Legionella sit between 20 and 45 degrees Celsius. This is the temperature in which the bacteria will naturally have the right conditions to grow. If they are able to multiply then it is very easy for the water system to become fully infected and require significant action, including testing and treatment.

If you have any concerns whatsoever about legionella living within your water system it is crucial that you carry out tests and take action if the results show the bacteria living in this zone.

What Government Guidelines Say About Legionella

The official guidelines are crucial when it comes to meeting your responsibilities.

Hot water supplies must be kept at a very minimum of 60 degrees Celsius. Cold water should never rise above 20 degrees Celsius.

Though Legionella will grow most effectively within a range of 20 to 45 degrees Celsius, this extra buffer is in place to help ensure that the bacteria are killed off wherever possible.

Robinsons Facilities Services are available to help with your Legionella issues. Our team are trained, accredited and experienced in all aspects of Legionella control and can work with you to manage exposure and minimise the risk to your employees and visitors. This can ensure your ongoing compliance, so give us a call today and we can sit down with you and discuss your Legionella control and how we can help with it. We specialise in Legionella risk assessments as well as training and testing.