Industry insight
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Countering legionella risks in residential environments
The Legionella threat is often overlooked in residential plumbing and heating systems, yet it poses a serious hazard. It’s important for installers to inform their customers about this risk and strive towards its mitigation, especially in larger, older homes. Steps can be as simple as fi tting an eff ective hot water recirculating pump, says Andy Thompson, national sales manager for plumbing and heating at Wilo
L
egionella bacteria cause Legionnaires’ disease, a potentially fatal pneumonia variant. Although everyone can be aff ected, certain factors, like
age, increase vulnerability. This disease is typically associated with large commercial establishments like hospitals and hotels, where bacteria can usually be present in engineered water systems, such as cooling towers and spa pools. However, the threat is closer to home than realised, with Legionella able to thrive in any plumbing and hot water system’s pipework.
The risk tends to rise with the building’s age
and any modifi cations in the plumbing system. The majority of privately-owned houses in England, built before 1919, present such concerns. Although Legionella is dangerous, especially for the elderly, awareness about its initial symptoms is relatively low in the UK as people often dismiss initial mild symptoms as a common cold or fl u. Incidents of the disease are rising across
Europe, resulting in increased scrutiny, as seen in the EU Drinking Water Directive. The World Health Organisation (WHO) categorises Legionella infection as the most burdensome water-borne pathogen in the EU, stating that “since many countries lack appropriate methods of diagnosing the infection…the rate of occurrence is unknown”. The European Centre for Disease Prevention and
Control data shows France, Germany, Italy, and Spain account for 72% of all reported cases. Legionella Control International accredits the 30,000 cases across Europe to more humid conditions alongside an ageing population.
Unseen domestic dangers
With people going on holiday and vacating their properties, the risk of Legionnaires’ disease increases
Left: Andy Thompson, national sales manager for plumbing and heating at Wilo
due to water stagnating in pipework or shower heads, causing an ideal breeding ground for Legionella. However, any unfl ushed water pipes could pose a threat as they provide the perfect breeding ground for bacteria. So, how can installers prevent bacterial growth and rule out the possibility of Legionella development in homes?
Installer’s guidelines
When looking at designing out Legionella risks, installers must follow best practices when undertaking new installations and repairs to existing plumbing systems, such as: ¡ Removing ‘dead ends’ in pipework: Dead ends accumulate stagnant water and provide ideal conditions for Legionella. Any pipework section that isn’t fl ushed regularly is considered a dead end. These pipe sections can be long or short, with sections as small as 25cm still able to become a breeding ground for Legionella. ¡ Boiler temperature: Boilers should not be set below 65°C, particularly in the case of combi boilers or boilers heating a hot water tank system. ¡ Hot water storage systems: These should be maintained at 60°C. ¡ Flush: Regularly fl ushing out the water prevents stagnant water build-up and maintains water movement. Flushing the system with water at 60°C after an extended vacant period will kill any lingering Legionella bacteria.
Intelligent pumps for Legionella control
In addition to best practices, taking regular water samples and protecting water sources from contamination helps minimise bacteria growth risk. The Health and Safety Executive recommends regular professional inspections for commercial properties
10 September 2023
and landlords in both private and public sectors. For private homeowners, installers can help curb Legionnaires’ disease incidents by consistently educating them about the risks. They can also recommend and fi t innovative pumps, such as Wilo’s Stratos-PICO Z, to proactively minimise the disease’s contraction.
Designed for residential and light commercial
properties, such a pump ensures the safety of hot water and drinking water systems. It activates as soon as the system temperature drops below 55°C, and an in-built timer keeps water circulating regularly in the system, leading to less water wastage. This is because the hot water gets to the outlet much faster, so homeowners and tenants do not need to run the tap for a long time before the hot water reaches the outlet. The pump also contains many smart features, including EC motor technology that makes it much more effi cient over AC equivalents, and it has innovative auto thermal disinfection functionality built in. The latter means the pump can ‘learn’ the boiler routine. If ‘thermal disinfection’ is switched on and the pump detects a decrease in temperature in the system, it will automatically run to fl ush hot water around the system and kill bacteria. Alongside smart operating features, installers should look toward using pumps that can solve age- old installation challenges. For example, they are quick and easy to set up because they have a large colour display with simple settings and is available in up to an 8-metre head. Bluetooth functionality means the pump can be paired to an app on installers’ phones, so settings can be checked and changed remotely, rather than needing to crawl into tight spaces, all to help speed up jobs and make the life of an installer easier.
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