Many people associate Legionella with large commercial buildings that have complex HVAC systems – such as hospitals or spas – but it may be more of a problem in domestic properties than you realise. 

A few years ago, the now defunct Public Health England carried out some research that indicated Legionella is on the increase in dwellings, lurking in up to 1.5 million households in the UK. Researchers think that this well-known bacteria could be to blame for hundreds of cases of unidentified infection each year. 

The bacterium Legionella pneumophila causes Legionnaires’ Disease, a potentially life-threatening illness that presents symptoms such as fevers and organ failure. On average, there are 400-450 cases each year in the UK, with a mortality rate of approximately 10%, however, 2019 saw 503 cases. 

Outbreaks can be prevented through proper system design and maintenance, and management by the householder, landlord, and operative. 
It’s worth bearing in mind that Legionella loves:

• Warmth – Legionella bacteria thrive in temperatures from 20°C to 45°C. Hot water cylinders should store water at 60°C or higher and distribute it at 50°C or higher to ensure any bacteria is killed off before it has a chance to multiply. Make sure pipes are insulated to prevent heat transfer. Thermostatic mixer valves should be installed to protect against scalding, but they should be fitted as close as possible to outlets to prevent stagnation
• Stagnation – buildings that are out of use, for example, rental properties or holiday lets, pose an increased risk if outlets such as showers are used infrequently. Stagnation can be easily prevented by flushing out taps and shower heads on a weekly basis and keeping outlets free from grime and scale
• Cosy corners – stagnation can quickly occur in dead legs if systems have been modified over the years. Plumbers can help by removing redundant pipework and storage tanks to ensure all parts of the system are free flowing
• Sludge and scale – debris such as rust, sludge, scale, and biofilm feeds bacteria growth. A thorough cleaning and flushing will remove sediments, and water system disinfection will minimise risk where contamination is suspected, or prior to a new occupancy
• Super spreaders – when contained in a water system, Legionella does not pose a risk to human health. It is once it become airborne through shower heads, taps, or hot tubs that it becomes a problem. Identifying at-risk outlets is key to occupant safety. 

The law

Legal obligations and best practice are set out in the Approved Code of Practice for Legionnaires’ disease: The control of Legionella bacteria in water systems (ACoP L8) from the Health and Safety Executive (HSE) and HSG274 Legionella Technical Guidance. 

ACOP L8 is not legislation, but it does hold special legal status. In the event of a prosecution for a breach of health and safety law, the defendant will have to provide evidence of compliance, or the Court could find them at fault. 

Landlords, including private sector, local authorities, housing associations, hostels, and housing co-operatives, have a legal responsibility to keep their tenants safe from hazards and risks relating to the property. 

As the ‘duty holder’ they must undertake a Legionella risk assessment or, if they do not feel competent to do so, they can appoint someone else to do so on their behalf, for example, a plumbing operative. 

If duty holders and operatives follow guidance provided by the HSE then they should be doing enough to comply with the law.

Learn about Legionella

Legionella should not be overlooked in domestic settings. Quality training, delivered by industry experts, is the best way for plumbers to:

• become familiar with HSE guidance
• feel confident that they know their responsibilities
• take necessary action to prevent Legionella growth
• provide appropriate treatment to combat risks 
• advise customers on how to protect themselves, their families, and tenants. 

Legionella awareness courses for operatives train plumbers to undertake Legionella risk assessments and provide effective disinfection services, including treatments such as bleach, chlorine, and silver hydrogen peroxide.

Expert training providers with specialist industry experience will provide best value, delivering flexible, tailored training to suit individual needs. The best way to mitigate the risk of Legionella and ensure compliance is through quality training.