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020 4532 7773If you own or manage a property in London, you may have come across the term Legionella risk assessment and wondered whether it applies to you. The short answer for most landlords and building managers is yes. But there is still a great deal of confusion about what a risk assessment actually involves, how often it needs to be done, and what happens once it has been carried out.
This guide sets out the basics clearly, so that anyone responsible for a residential or commercial property can understand their obligations and know what to expect from the process.
Legionella is a type of bacteria found naturally in freshwater environments such as rivers and lakes. In low concentrations it does not typically pose a health risk. The problem arises when it enters man-made water systems, where the right combination of temperature, stagnation and nutrients can allow it to multiply to levels that are dangerous to human health.
When water containing Legionella bacteria is turned into a fine mist or spray and inhaled, it can cause Legionnaires disease, a serious form of pneumonia that can be fatal, particularly in older adults and people with underlying health conditions. It can also cause Pontiac fever, a milder flu-like illness.
Legionella growth is most likely when water temperatures sit between 20 and 45 degrees Celsius, when water is stored or recirculated rather than flowing freely, and when there is sediment, scale or other organic matter in the system that the bacteria can feed on. These conditions are not uncommon in the water systems found in many London properties.
A Legionella risk assessment is a formal evaluation of a property's water system to identify whether conditions exist that could allow Legionella bacteria to develop and what measures need to be put in place to manage that risk.
The assessment looks at all parts of the water system, including cold water storage tanks, hot water cylinders, pipework, showers, taps and any other outlets. It also takes into account factors such as water temperature, flow patterns, any dead legs or sections of redundant pipework, and the overall condition and maintenance history of the system.
The findings are written up in a formal report that identifies any risks present, categorises them by level of concern, and sets out the recommended remedial actions. Where the assessment identifies an immediate risk, action should be taken promptly. Where the risks are lower, they are typically addressed as part of an ongoing water safety plan.
The assessment should be carried out by a competent person with the appropriate knowledge and experience of water hygiene and Legionella control. At London Water Treatment, our Legionella risk assessments are carried out in line with ACOP L8 and BS8558, with full written documentation provided on completion.
The legal requirement for a Legionella risk assessment comes from the Health and Safety at Work Act 1974 and the Control of Substances Hazardous to Health Regulations 2002. These place a duty on employers and those in control of premises to assess the risk from Legionella and put appropriate control measures in place.
For commercial properties, the requirement is straightforward. If you own or manage a commercial building with a water system, you are required to have a Legionella risk assessment and to manage the risks it identifies.
For residential landlords, the position is slightly different but the requirement is still real. The Health and Safety Executive's guidance is clear that landlords of domestic rental properties have a duty to assess and manage Legionella risk. This applies whether you are a large portfolio landlord or someone renting out a single flat. The assessment for a simple domestic property is generally less involved than for a large commercial building, but it is still a requirement and not something that can simply be ignored.
Where a property is vacant, the requirement does not go away. In fact, as covered in our earlier post on Legionella risk in vacant properties, an empty building can present a higher risk precisely because the water system is not being used regularly.
There is no fixed interval in ACOP L8 that specifies exactly how often a Legionella risk assessment must be repeated. The requirement is that assessments are reviewed regularly and updated whenever there is reason to believe the current assessment may no longer be valid.
In practice, most water hygiene professionals recommend reviewing the assessment every two years as a baseline. However, a review should also be triggered by any significant change to the water system, a change in how the building is used or occupied, a period of extended vacancy, any indication that the water system is not performing as expected, or any suspected or confirmed case of Legionnaires disease linked to the property.
For properties with more complex water systems or higher risk profiles, more frequent monitoring and review may be appropriate.
Once the risk assessment has been completed and the report delivered, the next step is to act on the findings. Where remedial work has been identified, this should be carried out in a timely manner. Where the assessment has confirmed that the system is in good order, the findings still need to be documented and kept as part of the property's water safety records.
For many properties, particularly those with cold water storage tanks, the assessment may recommend a tank clean and disinfection, a chlorination of the pipework, or ongoing monitoring of water temperatures and outlet usage. These are standard follow-on actions that form part of a proper water safety plan.
If the assessment identifies a more significant issue, such as evidence of Legionella in a water sample, a more thorough remediation programme will be required, including disinfection, resampling and a review of the control measures in place.
Our team at London Water Treatment can support every stage of this process, from the initial risk assessment through to tank cleaning, chlorination and ongoing monitoring.
If you are a landlord or building manager in London and you do not currently have an up-to-date Legionella risk assessment for your property, arranging one is straightforward. We offer same-day Legionella risk assessments across London for both residential and commercial properties, with full written reports provided on completion.
Whether you manage a single rental flat, a portfolio of residential properties or a large commercial building, our team can carry out a thorough assessment and give you the documentation you need to demonstrate compliance.
To book a Legionella risk assessment or to find out more about what is involved, contact our team at London Water Treatment today. Call us on 020 4532 7773 or visit our Legionella services page for full details.
