WATER SYSTEM SAFETY
Addressing ‘Unholy Trinity’ of Legionella threats
Dr Richard Bentham, associate director at Built Water Solutions – a specialist water treatment company in Clarendon, South Australia, and Associate Professor, Public Health Microbiology, at the College of Science and Engineering at Flinders University in Adelaide, Muhammad Atif Nisar, a Postgraduate Research Student, and Dr Harriett Whiley, senior lecturer, Environmental Health, at the same educational establishment, discuss addressing the ‘Unholy Trinity’ of factors that can lead to Legionella colonisation and spread.
Water systems are an integral part of any large building. They are a critical component of a healthcare facility. Safe water is a given for operation of your facility. Nevertheless, statistics from across the globe show Legionella colonisation in the majority of healthcare facilities. The data also shows cases of disease associated with hot, warm, and cold water supplies. The past two years have seen a flurry of activity in healthcare in response to the COVID-19 pandemic. Necessarily this has meant prioritising ‘essential services’, and naturally this has resulted in diverting attention from other services, and in some cases redundancies. The ‘tidal’ nature of the pandemic impacts on healthcare has meant multiple re- opening and recommissioning of services From a building water system perspective, the situation caused by the pandemic is not new. The issues surrounding water safety have not been changed by the pandemic. It is a magnification of the existing status quo. The three enemies to be tackled are the same, and, unless addressed, will persist when (hopefully) the COVID-19 pandemic is a memory.
As the title (used by the authors in the original article when it appeared in the IHEA’s Healthcare Facilities magazine, ‘Obstruction, stagnation, and fermentation: The unholy trinity of healthcare water systems’) suggests, the three enemies are obstruction, stagnation, and fermentation. That is: restricted flow, low flow, and loss of temperature control. These three factors are the ‘Unholy Trinity’. They are a trinity because they are intimately linked and combine to create ideal conditions for Legionella and other bacteria to grow in hot, warm, or cold water systems.
A bathroom becomes office space in a hospital with pipes capped off at the wall.
The Unholy Trinity is operational and effective in supporting Legionella colonisation even in systems that are continuously or routinely disinfected. Disinfection is outside the scope of this article – but suffice to say if you don’t have control of the trinity, you don’t have a hope of effective disinfection.
Current control strategies One of the pitfalls of regulation is that it often precedes the evidence. In a crisis it is essential to act rather than wait for the evidence. Actions taken that appear to have resolved the crisis are then worked into regulations and guidelines. Once enshrined in law these actions become ‘facts’ regardless of their evidence base. The scientific basis for these ‘facts’ may be very weak or none-existent. This is not
This article, entitled ‘Obstruction, stagnation, and fermentation: The unholy trinity of healthcare water systems’, was first published in the Spring 2021 edition of Healthcare Facilities, the official magazine of the Institute of Healthcare Engineering, Australia. HEJ thanks the three authors, the magazine’s publishers, Adbourne Publishing, and the IHEA, for allowing its reproduction here in slightly edited form.
only true for Legionella and building water systems, but for many other disciplines as well.
Our regulations are peppered with
‘de-facto facts’ – things we accept as true without any evidence. A simple and obvious example from the Legionella discipline is ‘Legionella does not multiply below 20˚C’. This may be true, but there is no published scientific evidence to substantiate this ‘de-facto’ fact. You will also find there is no evidence to show that less than 10 cfu/mL of Legionella in potable water is safe.
Compliance without controlling the problem One of the upshots of this is gap in translation of evidence into regulations is that compliance may be achievable without reaching the end goal of controlling the problem. Another is that energy is expended on activities that may not be effective. In short, compliance may not be enough to protect health, and this has been proven on many occasions in the past. Control strategies based around
November 2021 Health Estate Journal 23
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