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Countering Legionella Risks in Residential Environments

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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 fitting an effective hot water recirculating pump.

Understanding Legionella and its dangers

Legionella bacteria cause Legionnaires’ disease, a potentially fatal pneumonia variant. Although everyone can be affected, 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 modifications 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 flu.

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 due to water stagnating in pipework or shower heads, causing an ideal breeding ground for Legionella. However, any unflushed 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 flushed 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 flushing 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 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 fit innovative pumps, like Wilo's Stratos-PICO Z, to proactively minimise the disease's contraction.

This Wilo pump, designed for residential and light commercial properties, 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 efficient 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 flush 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. The Stratos-PICO Z, for example, is quick and easy to set up because it has 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 tocrawl into tight spaces, all to help speed up jobs and make the life of an installer easier.

The threat posed by Legionella demands that installers take responsibility in protecting customers against the disease. Wilo's Stratos-PICO Z gives both installers and their clients assurance that steps have been taken to prevent Legionella in residences.