UK cases of Legionnaires’ disease are rising. With this, it becomes even more important for facilities managers (FMs) to stay informed about the latest technologies and best practices in Legionella control to help to ensure better protection for the buildings they serve.
Here, Greg Rankin at Legionella testing expert Hydrosense explains how the next generation of rapid testing can help FMs to raise the bar in Legionella control and help maintain a safer environment for all building occupants.
The task for today’s FM is ever‑complex. In this modern age of mounting legislation, environmental concerns and increasing onus on cost‑efficiency, there are a multitude of considerations. Take the washroom, for example; as well as the principal concerns of hot water safety, water efficiency and hygiene, functionality and maintenance are increasingly important. Though, perhaps, not always a foremost priority for some commercial premises, not to be an understated concern amongst this is Legionella control.
Rising Risk
To better understand the need to place sharpened focus on Legionella control measures and practices, let’s first consider the scope of the risk.
As most FMs will already be aware, Legionella is a naturally occurring bacteria widespread in ponds, rivers, and other natural water systems. When this bacterium enters water systems in the built environment, conditions such as water temperature and ineffective disinfection levels, can encourage rapid growth. Common sources of Legionella bacteria in buildings include cooling towers, taps, showers, air conditioning units, and hot water tanks.
Legionnaires’ disease is a potentially fatal lung infection caused by inhaling droplets of water containing Legionella bacteria. If the infection is not contained or treated early on, it can cause confusion, coma, heart failure and ultimately death. According to the World Health Organisation (WHO), the death rate for Legionnaires’ disease in untreated immuno‑suppressed patients could be as high as 40‑80%.1 Moreover, Legionnaires’ disease has been seen to cause health related quality of life impacts to the large majority people who have recovered from it.These include fatigue, neurologic and neuromuscular symptoms, and post‑traumatic stress disorder.
And by all accounts the Legionella risk is rising. In the most recent government statistics, there were 604 cases of Legionnaires’ disease reported in 2023 across England and Wales – the highest annual figure seen to date.2 And the expert consensus is that this upward trend will continue as factors such as climate change, warming temperatures and increasingly complex water systems continue to contribute to the rapidly increasing count.
Importantly, the risk of Legionella proliferation is generally greater in commercial premises due to a myriad of reasons. Foremost, commercial properties often have larger and more intricate water systems, including cooling towers, air conditioning units, and extensive plumbing networks, which provide more opportunities for Legionella bacteria to grow and spread. One study found that cooling towers in particular, commonly found in industrial and commercial businesses, have contamination rates as high as 49% in some regions.3
Also, larger buildings typically found in commercial settings have more extensive water networks, increasing the potential for stagnant water and areas of low water flow, which are conducive to Legionella growth. The scope for periods of low occupancy or disuse brings further risk due to water stagnation, creating ideal conditions and breeding grounds for Legionella growth.
Best Practice Challenges
Of course, the established approach to preventing Legionella growth amongst FMs is 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 flushed out regularly and all outlets should be, as required, de‑scaled and cleaned.
As part of this, Thermostatic Mixing Valves (TMVs) are typically used to allow the water to be stored and distributed at the required temperature to kill harmful Legionella bacteria, but reduce it to a safe temperature at the point of use by mixing it with cold water supply.
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 depends on implementing a robust maintenance programme, including regular flushing 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. The scope for periods of low occupancy or disuse, leading to water stagnation and increased risk of bacterial growth.
The end result is that it is becoming more important than ever for FMs to pay extra diligence to how they assess, test, and control the risk of exposure to Legionella bacteria in the face of changing environmental conditions.
Better Detection, Better Protection
So, what is to be done? Foremost, the recommendation is for FMs to prioritise more frequent and more robust water quality testing for Legionella in distribution systems.
Most FMs will already be well acquainted with the standard lab‑culture method – whereby water samples are collected from water systems on site and sent to an accredited laboratory which will identify the presence or absence of Legionella. 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 FMs and the premises they serve. Water samples can also get damaged in 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 (VBNC) Legionella– 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. The result can be a false sense of security, with the potential for lab results to state a negative outcome when repeated subsequent tests confirm non‑conformance.
Arguably then, as Legionella risk evolves, there is a clear case for FMs to consider including rapid testing as part of the Legionella testing process.
Designed to overcome the limitations of traditional Legionella detection, the latest generation of rapid testing kits enable the detection of Legionella in just 25 minutes and are incredibly accurate at quickly detecting the most common and potentially fatal species of Legionella bacterium – Legionella pneumophila.
Detecting Legionella pneumophila so quickly empowers FMs and all other duty holders to react promptly to contamination and take appropriate action, thereby significantly minimising the risk of exposure and human infection. Not only does using this method for routine testing help reduce risk and minimise potential exposure to building occupants, but it also offers additional information during necessary reviews of the risk assessment.
Safety First
As the frontline defenders against Legionella, FMs are already responsible for implementing and overseeing comprehensive water management plans to include regular risk assessments and ensuring that all water systems are regularly inspected and maintained. By incorporating next generation rapid Legionella testing technology into their safety protocols, FMs have an opportunity to ensure due diligence, minimise legal liabilities, safeguard the health of individuals within their premises and, ultimately, raise the bar in Legionella control.
1: https://www.who.int/news‑room/fact‑sheets/detail/legionellosis
3: https://estudogeral.uc.pt/bitstream/10316/115283/1/Legionella_CoolingTowersEDesign_Final.pdf
