WATER HYGIENE AND SAFETY
Flow-through expansion vessels cut Legionella risk
Amy Sedgwick, Assistant commercial product manager at Groupe Atlantic UK – designer, manufacturer, and distributor, of engineering solutions for hot water generation and commercial and residential heating applications – discusses some of the key ways to prevent the growth and proliferation of Legionella bacteria in healthcare water systems – including via the use of flow-through expansion vessels.
Legionella bacteria can breed in any water system, and can cause a wide range of diseases. When designing and installing a safe hot water system, it is vital to mitigate against the risk of a spread of pathogenic bacteria – particularly in healthcare premises or care homes – using appropriate protective equipment, as recommended by the Department of Health,1
and often also via the use of a flow-through expansion vessel.
Legionella bacteria – sources and risks Legionella pneumophila, the bacterium which causes Legionnaire’s disease, is commonly present in low numbers in natural water sources such as rivers, lakes, and reservoirs, but can also be present in man-made water systems, including hot and cold water systems. Legionella can thrive whether water is stagnant or flowing and – given the right temperature and conditions – can multiply rapidly.2
Once the bacterium has grown and multiplied inside a building’s water system, bacteria may be dispersed in the air in small water droplets (aerosolisation), or through aspiration when drinking infected water. If inhaled, this waterborne pathogen can cause legionellosis (a term which covers all diseases caused by Legionella), including the pneumonia-like Legionnaires disease, or the milder, ‘flu- like’ Pontiac or Lochgoilhead fever. Legionnaires’ disease, specifically, occurs when the bacteria infect the lungs after a person inhales droplets containing Legionella bacteria, and is similar to other types of pneumonia, in that it includes symptoms such as coughing, shortness of breath, fever, muscle aches, and headaches. All of the diseases caused by Legionella can be very dangerous for the clinically vulnerable or elderly and, therefore, guarding against the risk of spreading the bacteria in healthcare and care facilities is an imperative.
A rise in infections
Legionellosis diseases are rare, but recent studies are showing a rise in infections in the UK, particularly in healthcare facilities, with Public Health England3
reporting
over 500 cases in England and Wales in 2019. The disease can be very serious, particularly to those with a weakened or compromised immune system. In the UK, roughly seven in every 100 people (7%) who fall ill with Legionnaires’ disease will die.4
This is significantly higher than the mortality rate for seasonal flu (0.1%) and COVID-19 (between 0.6% and 1.6% according to 2020 studies).5,6 Once Legionella is present within a water system, water droplets carrying the bacteria can be dispersed from any number of devices and functions linked to that system. These could include, but are not limited to: n Hot and cold water storage tanks. n Water heaters. n Water filters. n Manual and electronic taps. n Aerators. n Spas and hot tubs. n Showerheads and hoses. n Pipes, valves, and fittings. n Ice machines. n Centrally installed humidifiers, misters, and atomisers etc.
n Medical equipment (CPAP machines, hydrotherapy equipment, bronchoscopes).
Legionella bacteria in water.
Understanding prevention The key is understanding prevention, and paying particular attention to the design and implementation of any hot or cold water system to prevent the formation and growth of Legionella and other bacteria. Building and estates and facilities managers, and owners and occupiers of hospitals, care homes, and other healthcare facilities – in particular – continuously work to ensure that the quality of water throughout their hot and cold water systems is safe, clean, and properly managed, to reduce the risks of infection. In 2018 a hospital was fined £300,000,7
and a private care home April 2021 Health Estate Journal 45
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