Legionella And The Need For Next-Generation Detection: Steps Water Utilities Can Take To Alleviate The Risk
By Greg Rankin
As water systems grow more complex and climate patterns shift, Legionella is emerging as one of the most persistent and underestimated risks in the built environment. The result is that the threat to public health from Legionnaires' disease will likely further escalate unless decisive action is taken, at pace.
There are several factors that may help explain the recent surge in cases of Legionnaires’ disease — a potentially fatal form of pneumonia caused by inhaling Legionella bacteria — across the U.S. in recent years.
Foremost, Legionella thrives between 77°F and 113°F. As climate change continues to alter our environmental conditions, rising temperatures, longer warm seasons and shifting rainfall patterns are creating more favourable conditions for Legionella to thrive in water systems.
At the same time, many distribution systems and plumbing networks across the country suffer from aging pipes, oversized layouts and stagnant dead-ends. These low-flow zones diminish disinfectant residuals, promote biofilm formation and create pockets where Legionella can multiply unchecked. Many legacy plumbing systems also lack modern design features, such as efficient temperature control and disinfection mechanisms, that help prevent bacterial growth.
Combine all these factors, and it becomes clear why Legionella cases are rising sharply across the U.S., with the number of reported cases of Legionnaires' disease having risen by 200% in the past 10 years.1 Other estimates suggest that Legionnaires’ disease now affects tens of thousands of people in the U.S. each year, and the consensus among health experts is that this upward trend is likely to continue.2
Importantly, the risk of Legionella proliferation is even more profound in water utility systems, as research reveals that rising average air and ground temperatures can increase the base temperature of cold water systems, potentially leading to increased Legionella growth in both cold and hot water distribution. Moreover, rapid shifts from drought to downpours, something which is becoming more common in all areas of the world, are known to create favourable conditions for Legionella growth in water distribution systems. At the same time, rising temperatures also increase demand for water sources, placing a new strain on water utilities.
The result is that it is becoming more important than ever for water providers to pay extra diligence to how they assess, test and control the risk of exposure to Legionella bacteria in the face of increasing risk.
So, what is to be done? Foremost, the recommendation is for water professionals to prioritise more frequent and more robust water quality testing for Legionella in distribution systems.
Of course, water management professionals will already be well acquainted with the standard lab-culture method as the oldest and most widely accepted technique for the detection of Legionella bacteria. However, this approach has limitations that can hinder timely responses to potential outbreaks.
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 businesses, employees, and the public. 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 Legionella (VBNC) — which, though dormant, can still be incredibly dangerous due to their ability to resuscitate and cause an infection. The result can be a false sense of security, with the potential for lab results to state a negative outcome when repeated tests confirm non-conformance.
Arguably, then, as the challenges posed by Legionella evolve, there is a clear case for water utilities to reconsider their testing strategies and embrace more innovative, efficient methods.
One such example can be found in the latest generation of rapid Legionella testing, which has been purposefully designed to overcome the limitations of traditional Legionella detection by providing on-site testing without the need for lab facilities. Incredibly easy to use, these tests enable duty holders to inspect water systems in only 25 minutes and provide an accurate and reliable result on the presence or absence of Legionella pneumophila bacteria — the primary cause of Legionnaires’ disease.
The benefits of using this smart and simple method in addition to traditional testing methods are vast. Principally, rapid testing facilitates early detection of Legionella, which is essential in preventing outbreaks. In this way, the ability to gain an immediate picture of Legionella empowers water professionals to react promptly to contamination and take appropriate action, thereby significantly minimising the risk of exposure.
Improved resource allocation is another major benefit for busy water providers, whereby teams can action remediation efforts almost immediately upon detection rather than having to wait on delayed lab results. Further down the line too, these types of tests can be used to support immediate remediation works through the ability to check post-remediation efficacy in real-time as opposed to having to wait for a lab to confirm for nearly two weeks. In this way, by implementing rapid testing methods, water professionals can demonstrate a robust, proactive health and safety that goes even beyond compliance and, in turn, secure peace of mind in knowing they have done the utmost to alleviate what is an increasing Legionella risk.
As climate change and ageing water infrastructure continue to accelerate Legionella growth, the risks facing water systems are rising faster than traditional testing can keep pace. By integrating next-generation rapid testing alongside existing practices, water providers can build a more proactive, resilient approach — one that better protects public health and keeps pace with an increasingly complex risk landscape.
1 https://wwwnc.cdc.gov/eid/article/28/3/21-1435_article
2 https://www.cdc.gov/legionella/php/surveillance/surveillance-report-2018-2019.html
Greg Rankin is the CEO of Hydrosense, which is on a mission to make Legionella detection easier, faster, and more effective than ever before with its rapid Legionella testing solutions. Learn more at https://hydrosense-legionella.com/.