Feature 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 regions3
.
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
2:
https://www.gov.uk/government/statistics/legionellosis-in-residents-of-england-and-wales-2017-to-2023/legionellosis-in-residents-of-england-and-wales-2017-to-2023-report 3:
https://estudogeral.uc.pt/bitstream/10316/115283/1/Legionella_CoolingTowersEDesign_Final.pdf
fmuk 21
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44
