Legionella and the need for next generation detection

As Legionella continues to hit the headlines, Greg Rankin CEO at Hydrosense advises on the steps health and safety professionals can take to alleviate what is becoming a growing – and largely still underestimated – public health risk

Early into 2026, we have already witnessed significant Legionella outbreaks across the US, including a deadly cluster in Ector County, Texas, cases linked to a major apartment complex in Harlem, New York City, and an outbreak associated with a Las Vegas casino.

While the specific circumstances behind each incident may differ, one truth that remains abundantly clear is that Legionella cases are rising at an alarming rate across the US.

The result is that the threat to public health from Legionnaires’ disease – a potentially fatal form of pneumonia caused by inhaling Legionella bacteria – will likely further escalate unless decisive action is taken, at pace.

But the big question is – what exactly?

A rapidly rising risk

Before answering that question, it is important to first explain the several factors attributed to Legionella’s recent ascent.

As most health and safety (H&S) professionals will already know, Legionella thrive in warm, stagnant water with the optimal temperature range for growth between 77°F to 113°F.

 As climate change continues to alter environmental conditions, rising average temperatures, prolonged warm seasons and shifting rainfall patterns are contributing to more favorable conditions for Legionella growth within building 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 may be easy to see why Legionella cases in the US have seen a 1,000 per cent increase in the past two decades alone and in an upward trajectory that experts predict will continue if not addressed.

The result is that it is becoming more important than ever for H&S professionals to pay extra diligence to how they assess, test and control the risk of exposure to Legionella bacteria in the face of increasing risk.

For many though, there remains a certain lack of clarity and standardization about what best approach to take.

Best practice, beyond compliance

Of course, most H&S experts will be well acquainted with the widely-adopted ASHRAE Standard 188 developed by the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), which provides a framework to implement comprehensive water management programs that proactively control risks related to the growth and transmission of Legionella in building water systems, including regular monitoring and maintenance.

Many states and cities also stipulate their own specific standards, especially in jurisdictions with recent outbreaks or stricter health requirements.

From our extensive experience in the Legionella field, though, we believe that current recommended practice simply doesn’t go far enough and there is scope to do much more to raise the bar on safety through a more robust and proactive approach to water safety.

For example, one of the most critical weaknesses exposed by many recent outbreaks is the lag between contamination and confirmation.

Traditional Legionella testing methods rely on laboratory culturing, which takes up to ten days to deliver results.

Yet Legionella can double in a day.

In a large building or cooling system, that delay can mean the difference between early intervention and widespread exposure.

Water samples can also get damaged in the transportation process, potentially killing the Legionella inside and leading to a false negative result.

In addition, culture-based testing cannot detect viable but non-culturable (VBNC) Legionella, which, though dormant, can 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 H&S professionals 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 H&S professionals to react promptly to contamination and take appropriate action, thereby significantly minimizing the risk of exposure.

Improved resource allocation is another major benefit whereby it’s possible to action remediation efforts almost immediately upon detection rather than having to wait on delayed lab results.

Further down the line, these tests can also support immediate remediation by enabling real-time verification of post-remediation effectiveness, rather than waiting nearly two weeks for laboratory confirmation.

In this way, by implementing rapid testing methods, H&S professionals can demonstrate a robust, proactive health and safety approach 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.

Making Legionella control water-tight

If the recent flurry of Legionella outbreaks seen this year has taught the H&S world anything, it is that we cannot afford to underestimate the scope of Legionella risk.

In the context of what is becoming a increasingly complex public health concern, effective management and control can only be achieved by going beyond compliance with proactive monitoring, rigorous control measures and a culture of continuous oversight that is truly water-tight.

For further information, please visit: https://hydrosense-legionella.com/

About Hydrosense

Hydrosense is on a mission to make Legionella detection easier, faster, and more effective than ever before with its innovative, world-leading rapid Legionella testing solutions.

Ideal for industries that require more stringent action levels, Hydrosense overcomes the limitations of traditional lab-culture testing with its innovative Hydrosense Legionella testing kits.

This includes the Hydrosense PRO range, which can detect the presence of Legionella pneumophila serogroups 1-15, and the Hydrosense ONE range, which can detect the presence of Legionella pneumophila serogroups 1 only.

Easy to use, accurate, and with results delivered in just 25 minutes, the result is the early detection of problems, speedy remedial action, and a reduction in potential exposure and the associated risks.