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Industry insight


The legionella lowdown: what installers need to know


A


s most heating and ventilation installers will already know, legionella is the bacterium that causes Legionnaires’ Disease. It can


be found in a range of man-made water systems including taps, showers, air conditioning units, pools and hot tubs. Though it can survive at temperatures up to 60°C, the bacterium fl ourishes between 20-45°C. Although most healthy people exposed to


legionella will not fall ill, for older people, young children, or those with specifi c health issues or conditions Legionnaires’ can prove fatal. What many installers may not realise, however, is that legionella rates are rising. Attributable to factors such as our warming world, more frequent weather extremes and increasingly complex water systems, recent years have seen a signifi cant surge in Legionnaires’ Disease cases across the world. In 2021, for example, the European Union witnessed the highest annual notifi cation rate of Legionnaires’ to date. In the UK, the total number of legionellosis cases have increased by over 20% between 2017 and 2023. As a result, it is more important than ever for


installers to stay informed about the latest solutions that can help public buildings optimise infection control. Installers play a vital role as custodians of public safety. However, there is an additional, critical consideration: two-thirds of heating and ventilation installers are aged 45 or older, with over a third aged 55 or older. Moreover, the workforce is predominantly male. Given that individuals over 50 face a higher risk of legionella, and males are statistically more vulnerable, installers working on unmanaged water systems may be exposing themselves to signifi cant health risks.


Preventative practices


Of course, the established approach to preventing legionella growth appears fairly simple; hot water should be stored above 60°C and distributed above 50°C, while cold water storage and distribution should be below 20°C. Infrequently used outlets should be fl ushed out regularly and showerheads de-scaled and cleaned. Thermostatic mixing valves (TMVs) play a key


role in this by allowing water to be stored and distributed at temperatures high enough to kill legionella bacteria, while reducing it to a safe temperature for use by mixing it with cold water. However, while TMVs are essential for minimising the risk of scalding, they can inadvertently increase the risk of legionella growth. This is because the blended water downstream of a TMV can create an environment conducive to the bacteria’s multiplication. Ensuring safe TMV use


Greg Rankin, chief executive at legionella testing authority Hydrosense discusses the increasing risk of legionella and the steps installers can take to fulfi l their role as public safety custodians


the transportation process, potentially killing the legionella inside and increasing the risk of a false negative result. Lab culture testing is also unable to detect Viable but Non-Culturable Legionella (VBNC) – which though dormant can still be incredibly dangerous due to their ability to resuscitate and reinfect a water system – also being able to directly infect human cells even in their dormant state. To address these limitations, the latest generation


Left: Greg Rankin, chief executive at legionella testing authority Hydrosense


of rapid testing kits enable the detection of Legionella in just 25 minutes and are incredibly accurate at quickly detecting the potentially fatal Legionella pneumophila. Not only does using this method during installation help reduce risk and minimise potential exposure, but it also off ers additional information during necessary reviews of risk assessment, and provides peace of mind for the customer.


What can installers do?


depends on implementing a robust maintenance program, including regular fl ushing to prevent water stagnation—a known factor for promoting Legionella. Despite this, the consensus is that TMV maintenance, inspections, and servicing are not necessarily always as thorough as they need to be.


Testing times


With this, it may be easy to ascertain why legionella cases can and do still continue to happen across all sectors, as demonstrated by regular headlines surrounding Legionnaires’ outbreaks. The good news in this is that there is scope


to address this and help raise the bar on safety through a more robust and routine legionella testing regime. For the uninitiated, most duty holders will tend


to rely on the lab-culture method - whereby water samples are collected from water systems on site and sent to a UKAS accredited laboratory which will identify the presence or absence of legionella – for legionella testing. However, this approach is timely, cumbersome and has limitations. Foremost, most lab culture tests take 7-10 days


to return results. Yet legionella can double in a day. This large time lag means increased exposure and risk for installers and the premises they serve. Water samples can also get damaged in


Inherently installers may not have been the obvious fi rst port of call when it comes to Legionella testing. However, given the scope of their works in the commercial fi eld and being so close to the front line there an obvious opportunity for this to change. By being proactive about legionella control and


providing on-site testing as part of an installation or maintenance package, installers have an opportunity to help to reduce liability risks for the commercial clients they serve. As awareness around growing legionella rates grows, this will further secure an installer’s reputation as a trusted professional dedicated to helping to protect the public, creating a competitive edge and helping attract more business especially from industries with heightened health and safety priorities.


Lightening the legionella load


There’s no doubt that building managers, owners and other duty holders tasked with keeping on top of ever-mounting legislation, effi ciency and decarbonisation targets and the like, would appreciate any additional support in tackling the developing Legionella risk. By incorporating rapid Legionella testing,


installers have an opportunity to create a competitive edge, boost revenue, help to optimise occupant safety and, in turn, provide peace of mind for their client.


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