WATER SYSTEM HYGIENE & SAFETY
Managing the ‘perennial issue’ of Legionella control
Since the pandemic, incidences of Legionnaires’ disease have been increasing in public buildings, according to the European Centre for Disease Prevention and Control. Carole Armstrong, Marketing manager at Delabie UK, looks at the current trend in healthcare facilities for removing thermostatic mixing valves to see whether this is a sustainable solution to managing the perennial issue of Legionella control.
In 2021 the European Union and European Economic Area saw the highest recorded levels of Legionnaire’s disease, with over 10,700 cases and 704 fatalities, according to the European Centre for Disease Prevention and Control (ECDC).1 Although the Centre said the exact reasons were unknown, they attributed the higher figures to three key factors – firstly, changes in national testing policies and surveillance systems which – in the context of the coronavirus pandemic, were naturally focused on identifying respiratory illnesses. Secondly, the Centre cites an ageing population, with increased susceptibility to pulmonary infections, and, thirdly, they identified as causative the design, infrastructure, and maintenance, of water systems used in buildings. It is this latter that raises alarm bells for healthcare estates and facilities and maintenance teams.
Public buildings ‘mothballed’ These results are, however, understandable. Excluding healthcare facilities and premises providing essential services, many public buildings were mothballed for prolonged periods during the pandemic, and not all facilities had a flushing regime in place. Maintaining water distribution temperatures was not always practical or economical. As a result, Legionella bacteria found a safe haven in the biofilm that forms inside the pipework – a source of nutrients, and a shield against thermal and chemical shock treatments. Over time, the biofilm matrix will break down, releasing free-floating bacteria into the water system. These bacteria pose a significant risk to vulnerable people when inhaled in an aerosol format such as steam. During the pandemic, the entire focus in healthcare facilities was on providing critical care for patients who were seriously ill, or protecting vulnerable patients/ residents from cross-infection. Many areas were reassigned – some seeing incredibly intensive use, while others were sidelined. Even in an environment where Legionella
Sequential thermostatic mixers and taps without NRVs.
control is second nature, it was not always possible to revise risk assessments, amend Water Safety Plans, and adapt flushing regimes to take account of these changes, however temporary.
Post-pandemic recommendations In the post-pandemic era, the ECDC recommendations1
for Legionella control
are reassuringly familiar: n Maintain cold water systems at below 20 °C, and hot water systems above 50 °C*, to prevent bacterial growth.
n Ensure proper water flow and circulation in water systems to minimise the risk of stagnant water.
n Ensure regular maintenance, cleaning, and disinfection of water systems.
n Disinfect hot water systems with high levels of (50 mg/l) chlorine for 2–4 hours after work on the system and water heaters, and before the beginning of every warm season.
It is worth noting that the ECDC article
states: ‘Regular checks for the presence of Legionella bacteria and appropriate control measures can prevent cases of Legionnaires’ disease at tourist accommodation sites, hospitals, long- term healthcare facilities, or other settings where sizeable populations at higher risk may be exposed to aerosols containing the bacteria.’1
Health & Safety Executive Guidance HSG 274 Part 2,2
meanwhile recommends:
‘Temperature control is the traditional strategy for reducing the risk of Legionella in water systems. Cold water systems should be maintained, where possible, at a temperature below 20 °C. Hot water should be stored at at least at 60 °C, and distributed so that it reaches a temperature of 50 °C (55 °C in healthcare premises) within one minute at the outlets.’ Either way, hot water at temperatures
above 50/55°C poses a significant risk of scalding to vulnerable patients, who are also those that are most at risk from
October 2023 Health Estate Journal 75
© Delabie
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