FLUID CONTROL Locking down Legionella risk on site
Amid rising concern about globally increasing cases of legionella, Greg Rankin, chief executive at rapid Legionella testing expert, Hydrosense explains why construction industry professionals must begin to take a much more proactive approach to reducing the risk
I
t’s widely established that the construction industry is one of the most dangerous job sectors in the world with risks from heavy machinery, working at height, hazardous materials and moving objects contributing to a significant number of injuries and fatalities every year.
What is, undoubtedly, less considered amongst these dangers is the risk of Legionella. Indicative of this, research reveals that over two thirds of construction sites do not have water safety measures in place prior to commencing works.1 And yet the reality is that Legionella - a bacterium that can cause a serious form of pneumonia known as Legionnaires’ disease - presents a very serious threat, especially for construction projects.
A perfect storm
Inherently, construction activity usually disrupts water systems, creating ideal conditions in which Legionella and other waterborne pathogens can thrive and proliferate. Key concerns include the scope for dirt, debris and other material to enter and contaminate water systems. And because systems are often disrupted for long periods of time during construction, stagnation occurs - one of the leading factors contributing to the growth of biofilm and Legionella bacteria. Stagnation also provides an opportunity for water in the pipes to reach ambient temperatures, and for residual disinfectant levels to drop, further exacerbating risk. At the same time, it’s widely established that people over 45 years old are particularly susceptible to Legionnaires’ disease. In the context of an aging construction workforce where the average UK construction worker is now aged over 502
becomes even more profound.
Place this altogether in the context of rapidly soaring Legionella rates and it’s easy to see why the Health & Safety Executive [HSE] clarifies that ‘work involving water or old / poorly maintained water systems might expose construction workers to Legionella’. This comes as one recent prominent study into the occupations at increased risk of acquiring Legionnaires’ disease found construction workers had 1.82 times the rate compared to non-construction occupations.3
Proactive protection and prevention
, the Legionella risk therefore
To address this, the HSE sets out specific obligations that construction sites must adhere to including the development of a site-wide Legionella Management Plan (LMP) that meets the requirements of the Approved Code of Practice L8 and HSG274 guidance. It also recommends the Assess, Control, and Review (ACR) model for managing health hazards, including Legionella, during construction and renovation. From our experience though, there is a real opportunity to raise the safety bar even higher by adopting a more dynamic testing regime - one that starts with routine, rapid on-site testing. The reality is that construction sites are uniquely complex, ever-changing environments. Traditional laboratory tests can take up to ten days to produce results, and during that window contractors and subcontractors are exposed to unnecessary risk. On top of that, water samples can be damaged during transport, sometimes killing the Legionella and leading to false negatives. Traditional lab-based tests also can’t detect Legionella in a state known as Viable but Non-Culturable (VBNC). Although dormant, these bacteria remain dangerous because they can resuscitate and infect human lung cells.
This means that a supposedly “negative” result can create a false sense of security, only to be contradicted by follow-up testing that reveals the true picture.
The latest generation of rapid testing kits is designed to overcome these limitations. They can detect Legionella in just 25 minutes and are highly accurate in identifying Legionella pneumophila, the species most commonly linked to outbreaks of Legionnaires’ disease. Detecting the bacteria so quickly empowers construction duty holders to take immediate action, significantly reducing the risk of exposure and infection. This approach doesn’t just minimise risk during day-to-day operations; it also provides valuable data for ongoing risk assessments, while offering peace of mind for the contractor, building operator and their responsible person.
Importantly too, construction sites are dynamic
environments where evolving activities such as demolition, excavation, re-pressurisation and such can all contribute to the Legionella risk. Rapid testing allows for frequent monitoring and adaptation to changing conditions.
Real-word risk
It is not hyperbole to say that Legionella remains one of the most significant yet largely overlooked health and safety risks facing the construction sector.
Just this May, its consequences became clear when a leading contractor was forced to halt a major development after Legionella bacteria were detected in the water supply.4
Beyond
the immediate dangers to worker health, the incident has since triggered lengthy delays, costly downtime and a financial hit running into the millions. And the unfortunate reality is that this is far from an isolated incident, as similar disruptions continue to surface across the industry globally. The recommendation then is for construction
professionals to take matters into their own hands by taking advantage of the new opportunity to establish faster, more immediately actionable, and more frequent Legionella testing. In a sector where reputation is everything, in this way proactively managing water safety is not just about compliance - it’s about protecting people, safeguarding projects and building better standards.
1.
https://www.mdpi.com/1660- 4601/17/6/2168
2.
https://ccemagazine.com/news/ construction-industry-workforce-crisis- 10000-workers-needed-by-2029/
3.
https://pmc.ncbi.nlm.nih.gov/articles/ PMC11167715/#:~:text=Among%20 occupations%20that%20may%20 not,%25%20CI%201.6%20to%202.1)
4.
https://www.constructionnews.co.uk/ buildings/legionella-setback-for-delayed- galliford-try-health-centre-22-05-2025/
6 BUILDING SERVICES & ENVIRONMENTAL ENGINEER NOVEMBER 2025
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