How to manage and reduce Legionella risk in a mixed property portfolio

by Charlie Brain, on 22-07-2025
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As is well discussed in our previous blogs and is “mostly” known by organisations in the UK, Legionella bacteria must be managed in all buildings where there is a foreseeable risk of exposure.

This blog aims to explore how organisations can effectively manage Legionella bacteria in mixed property portfolios.

ACoP L8 Guidance

To cover the basics, all organisations must, as stated in ACoP L8;

 

(a) identify and assess sources of risk;

(b) prepare a written scheme for preventing or controlling the risk;

(c) implement, manage and monitor precautions;

(d) keep water safety records of the precautions;

(e) appoint a competent person.

 

In some instances, that can be fairly straightforward, especially when only a single building is being managed, but there are some additional considerations and pitfalls when it comes to managing several buildings, particularly when they differ in more ways than one.

 

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Different buildings will always require different management

How they could vary are;

  • The size and complexity of the water/ risk systems

  • How often the building and water systems are used

  • The susceptibility of the occupants exposed

  • Being managed by different persons, i.e. by a different organisation on your behalf

  • The location of the building

For an organisation that has more than one building to manage, there are elements of the management that will cover all of them. Typically, an organisation will have a single policy, training may be managed centrally, and the persons undertaking the required management and technical tasks may be the same.

 

Assessing the need for a Legionella Risk Assessment

The first task an organisation may undertake is to identify which buildings should be considered for risk assessment. This can be achieved by undertaking a property risk screen. A property risk screen would categorise a mixed property portfolio by risk. It would consider occupant susceptibility, the number of occupants, duration of potential exposure, and types of water and risk systems.

 

Risk Assessment  Remedial Works  Legionella  LRA 700x525Prioritising mixed properties by foreseen risk would allow an organisation to undertake Legionella risk assessments in a manageable way. It may also show which properties may not require a risk assessment and/or elaborate control measures.

Once a Legionella risk assessment has been completed, this will hopefully begin to steer an organisation in the right direction for managing the risk. The risk assessment should indicate the inherent risk of a building; this will do 2 things;

  1. Ensure the control measures (including resources) are proportionate to the risk

  2. Understand what the full exposure could be if controls fail.

Understanding which are the “riskier” buildings will help organisations “cut their cloth” accordingly and allocate reasonable resources.

“Cutting the cloth” is understandably very difficult for an organisation to do, but a good risk assessment will enable appropriate action to be taken. Smaller buildings with simple water systems will require less management, especially where there are no highly susceptible occupants. Mains cold water, for example, requires less management than cold water storage tanks. Point-of-use water heaters, in contrast, require less maintenance than large circulating hot water systems.

Residential Accommodation v Healthcare

Blog-ACoP-HSG274-correct-sizeThe HSE also provides advice on residential accommodation. Where an organisation, such as a local government, manages large public buildings and a housing stock, there are simpler management tasks outlined in HSG 274, part 2, such as simpler checks.

Where an organisation has a mixed occupant susceptibility across their property portfolio, such as an NHS Trust with hospitals and office blocks, Legionella management would naturally differ. Less resources could be spent on staff buildings compared to patient use buildings. The additional control measures listed in the HTMs do not have to be applied to non-healthcare buildings, where the HSG documents are less demanding.

 

Legionella Written Scheme of Control and

Water Safety Plans

Satisfying the Legionella written scheme of control requirement of ACoP L8 is another sometimes tricky task. There must be a document that states what risk systems are within a building and how an organisation will manage those risks. Developing a written scheme document for each building may be too difficult to manage and keep track of, so a more holistic water safety plan, supported by asset registers, for the organisation may be more manageable.

Perhaps the most challenging part of Legionella management across a mixed property portfolio is planning preventative maintenance and maintaining a water safety record.

How to create a logbook?

Once the control measures are identified by the Legionella risk assessment and confirmed through the written scheme, a logbook of maintenance tasks will typically be formed. Maintenance tasks will vary from;

Perhaps the more traditional approach was to have hard copy log books at each site, thus being filled in after a task had been completed. But the requirement to audit these records and keep track of them becomes very difficult.

The perhaps more modern approach is to embrace technology and utilise electronic logbooks and software that can store records and be accessed centrally. This would allow different parties, such as contractors, to access records at all times. Some record-keeping software also allows for the analysis of data, dashboards, and handy reports to make Legionella management easier.

 

There is no escaping the fact that the more varied your property portfolio is, the trickier it will be to manage. Striving for simplicity and consistency has its limits. If all buildings were the same, they would be naturally easier to manage (think a UK-wide purple hotel chain and a worldwide fast-food burger outlet). Perhaps the key to it is to bring consistency to the inconsistencies where you can; develop overarching documents, use the same risk assessor, use the same training company, use the same logbook format, and use the same record-keeping structure. There are technologies and tools to help you.

Feel free to reach out if you have any questions about this blog or if you would like to consult with one of our experts for further advice on water hygiene.


Editor’s Note: The information provided in this blog is correct as of the date of original publication – July 2022.

 

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About the author

Charlie Brain

Charlie started the Water Hygiene Centre as a trainee risk assessor back in 2010, since then he has developed professionally from risk assessor, project manager and is now a Senior Consultant. During this time he has taken ownership of our risk assessment method and development of our bespoke reporting platform and has been key in our UKAS accreditation to 17020.

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