Preventing Legionella outbreak after lockdown – Part 2

Legionella Test

The coronavirus pandemic has changed our lives, with around 20% of the global population having experienced lockdown, everyone is feeling the impact. However, as the lockdown starts to ease, we need to take the necessary steps to ensure that there isn’t a second peak. Alongside this, we need to be careful about how buildings under lockdown can be safely reopened for public use.

At the end of March, a quarter of UK businesses stopped trading in a bid to prevent the outbreak from spreading. This means that plumbing and heating systems in empty restaurants, offices, hotels, hairdressers and many other public use buildings are left dormant. Stagnant water in these buildings can pose a serious health hazard when businesses start to re-open, which is why the APHC (Association of Plumbing and Heating Contractors) has already warned landlords, property owners and employers about the potential spread of Legionnaires’ disease.

In this blog, we will discuss what is Legionnaires, how it builds in stagnant water and what measures can be taken to prevent an outbreak. You can read the first blog in this series here.

What is Legionnaires’ disease?

Legionnaires’ disease (also known as Legionellosis), is a strain of atypical pneumonia and is caused by Legionella bacteria.

The symptoms of Legionnaires’ disease include coughing, shortness of breath, vomiting, diarrhoea, high fever, muscle pains, and headaches. Because the symptoms of Legionnaires are similar to those associated with coronavirus, the two can be easily confused.

Legionella grows in stagnant water supplies and multiplies in temperatures between 20-45°C. The bacteria are dormant below 20°C and cannot survive above 60°C. Humans contract Legionnaires by breathing in water droplets or particles that contain the bacteria.

Cooling towers, humidifiers, hot water systems, room-air humidifiers and central air conditioning systems are all sources of Legionella, and with many buildings under lockdown, the risk of the bacteria developing in the water systems is much greater. However, by carefully designing and maintaining the water systems, the risk of Legionnaires outbreak can be prevented.

Who is responsible for assessing the risk of Legionnaires’ disease?

It is the responsibility of landlords and employers to assess and control the risk of exposure to Legionella bacteria. They have a legal duty to carry out risk assessments, remedial work and take precautionary measures to protect employees and the general public against Legionnaires’ disease.

In order to avoid an outbreak of Legionnaires after the lockdown eases, it’s essential that all plumbing and heating systems that haven’t been used are thermally flushed and all water is completely drained from the pipework (you can read our blog ‘Legionella after Lockdown Part 1: Flushing the System’ to learn how to carry out these works).

Also, to ensure that the building is Legionella safe in future, proper specification and maintenance of pipes, valves and fittings is key.

testing tap water

Prevent Legionella with Thermostatic Mixing Valves

One way to reduce the risk of Legionella growth is by installing a Thermostatic Mixing Valve (TMV) before water outlets. TMVs allow the hot water to circulate at a constant high temperature (above 70°C), which stops the bacteria from breeding in the system, while ensuring safe water temperature from outlets. These specialised valves blend both hot and cold water to a preset temperature which can be no more than 48°C, hence preventing scalding accidents.

In 2012 it became a legal requirement to install TMVs in all commercial and domestic new builds or properties undergoing a ‘change of use’. The key to a successful installation is choosing the right TMV, as domestic, commercial and public buildings have different requirements to healthcare buildings.

easifit thermostatic mixing valve

TMVs in domestic, commercial and public buildings

Domestic, commercial and public buildings must use TMV2 certified valves that fall under the TMV2 scheme, such as the Easifit and Ausimix TMVs from our Reliance Valves brand. Under this scheme, TMVs must maintain a safe and stable temperature of under 48°C at all times and quickly shut off in the event of hot or cold water failure.

TMVs in healthcare buildings

Healthcare buildings must adhere to more stringent regulations, and require a TMV3 certified valve, such as Reliance Valves’ Heatguard TMV3-8, Ausimix and the Heatguard Dual. TMV3 accredited valves follow more rigorous testing processes with periodic checks six to eight weeks after installation.

These checks include a thermal element endurance, hot spike and stability test, and a response on temperature adjustment and fail stop valve check. If the valves aren’t checked within the required timeframe they may be marked as non-compliant and no longer be suitable for use.

You can learn more about TMVs in our Safety first with TMVs blog.

TMV valve

Anti-Legionella valves

Another way to prevent the growth of Legionella bacteria is by installing Anti-Legionella valves. Commonly used in conjunction with expansion vessels on commercial boilers, these valves stop water from stagnating in ‘dead legs’ of the pipework. The term dead leg, or dead end is typically used to describe a run of pipework that is no longer in use or a pipe that has become isolated from the regular flow of water.

Specifically designed to maintain water circulation with a standard single connection to the expansion vessel, these valves divert a portion of the flow into the vessel, continually renewing the water content. This makes it difficult for Legionella bacteria to breed and multiply in these parts of the water system.

To ensure maximum safety it is advisable to only use WRAS approved Anti-Legionella valves and carry out annual servicing.

FBSP Anti-Legionella Valve

Safeguarding people after lockdown

It is the responsibility of all landlords, employers or building owners to ensure that their buildings are safe for use. And ensuring that plumbing and heating systems are properly specified, designed and maintained before re-opening these facilities is key to protecting both employees and customers.

As plumbing and heating installers, it’s crucial to educate your customers about the potential health hazards associated with a stagnant water supply and take the appropriate preventive measures to protect end-users.

If you have any questions about how to thermally flush the entire system, or how our valves can help to ensure the safe delivery of water, get in touch with our team of experts who are happy to support and provide advice.

For the problem solvers, the urgent fixers, the everyday heroes and the truly up against it, we’re with you all the way.

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View our high performance Anti-Legionella Valves that prevent Legionella from breeding in cold water systems. 

Lee Halstead Headshot

Lee Halstead

Technical Sales Engineer - JG Speedfit/Reliance/SharkBite & JG Underfloor

About the author

As a seasoned professional in plumbing and heating, having earned City and Guilds Plumbing Craft and Advanced Craft certifications in 1991, I have dedicated myself to mastering the craft.

For over two decades, I operated as a self-employed plumbing and heating engineer, serving both residential and new build sectors.

In 2015, I transitioned into the role of a Technical Sales Engineer with RWC. In this capacity, I have leveraged my extensive field experience and technical knowledge to provide invaluable support and build strong relationships with customers. As a spokesperson for RWC, I am thrilled to share my expertise and promote the cutting-edge products and services we offer in the plumbing and heating industry.