Legionella Risk Assessment

A legionella risk assessment is a process used to identify and evaluate the risks of Legionnaires’ disease in a particular environment, and to implement measures to control or eliminate those risks. Legionnaires’ disease is a serious form of pneumonia that is caused by the bacterium Legionella pneumophila, which can be found in natural water sources, such as rivers and lakes, as well as in man-made systems, such as air conditioning systems and hot water tanks.

Every business in the UK, regardless of size, is legally required to conduct a legionella risk assessment to identify potential problems and protect staff, clients, and other stakeholders. Every landlord and business owner must follow this.


Why do I need a Legionella Assessment?

As an employer, or someone responsible for the control of premises (including property owners) which has a water supply, there is a legal duty to risk assess legionella hazards to ensure the appropriate management and control is in place to avoid anyone being exposed to legionella and other harmful waterborne bacteria.

The Approved code of practice (ACOP) L8 is the Health and Safety Executive legislative document covering the control of legionella and is supplemented by the Health and Safety executive guidance HSG274.

These are then enforced under the Management of Health and Safety regulations 1999 which make it mandatory to have a risk assessment in place.

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What is included with the Legionella Risk Assessment?

A competent and trained technician will visit the facility and complete a thorough inspection and assessment of all water supplies, storage and use for the facility including hot and cold water systems, process water and cooling tower plant if applicable.

As part of the legionella risk assessment and review, we assess all areas against strict Legionella compliance and perform all required testing.

If upon inspection or for high-risk processes and plants we identify a need to take samples, we will do so and send the samples to accredited laboratories for analysis of the Legionella bacteria. We take care of all these steps on your behalf and of course with your authorisation.

What is different about our approach?

We review the overall site water systems and benchmark them against the compliance areas for Legionella. We also do as much of the work as we can while we complete the assessment such as removing dead legs that can be removed, flushing taps, descaling, and sanitising shower heads etc and so once we have finished the Legionella assessment, you have a clean bill of health from day 1.

We also provide a free logbook with the risk assessment report, and we physically update the logbook while we do the assessment so that you have all of the records available.

We also provide ongoing support such as descaling taps, replacing taps if needed, sanitising and flushing water tanks and as much pr as little work as you need to achieve compliance.

Wherever possible we will encourage you, the client to do some of the easier work such as flushing taps. We are often engaged in discussions to agree with responsibilities such as Facilities, Engineering or Safety teams that debate if it is their role to complete due to the crossover of responsibilities.

Cooling Water

A Legionella assessment typically includes the following components:

Condition inspection of tanks

✅ Checks of pest activity

✅ Void spaces and roof Spaces where available

✅ Condition and temperature of Thermostatic Mixing valves (TMV)

✅ Temperature checks on all water systems

✅ Site Schematics are developed to display your facility water infrastructure network

✅ Flush all taps and outlets

Identify all dead legs and remove if it does not require system drain down

Dismantle and disinfect / clean showerheads while on site

Full details risk assessment report

✅ Written scheme of examination

✅ Complete site logbook – itemise and filled in during the assessment

✅ Reset thermostats to desired temperature and test until suitable temperatures are achieved

How much does a Legionella Assessment cost?

Unfortunately, it is the usual case with these types of things and the answer is – “it depends.” But we at Orbis do not like to sit on the fence. 

On average, our Legionella Assessments cost approximately £400. The cost examples below should help you understand what to expect for your facility. All costs are also subject to VAT.

In order to identify the sources of potential exposure to Legionella bacteria, the assessor will need to review relevant documentation, such as water system plans and maintenance records, and may also need to conduct site visits and interviews with workers.

Once the sources of potential exposure have been identified, the assessor will evaluate the risks associated with those sources. This may include evaluating the potential for exposure to Legionella bacteria through inhalation, as well as the potential for the bacteria to grow and multiply in the water system.

Based on the results of the risk assessment, the assessor will recommend controls to manage or eliminate the identified risks. These controls may include measures such as maintaining the water system to minimize the growth of bacteria, providing protective equipment for workers, and implementing safe work practices.

NOTE – If you have multiple sites, we can change the cost structure to a project-based approach as opposed to single sites and often results in significantly reduced costs because we change to a daily rate as opposed to a single site cost. Often, we can complete 2-3 small sites within 1 long day for example.

If this is your case, feel free to give us a call or message us and we will chat through the details and availability.

You can drop us a short email at [email protected], fill in a quick form on this page or call us on – 01656 470044.

We will be in touch as soon as possible, usually within 1 hour during office opening times or the next morning.



Legionella is a bacteria found in all-natural water sources and in small levels is harmless. However, as with any other bacteria, give it the right conditions and it will multiply to levels that become harmful when inhaled into the lungs causing a disease referred to as Legionellosis.

Legionellosis is a collective term for the diseases caused by legionella bacteria including the most common and serious Legionnaires' disease which is a potentially fatal form of pneumonia, as well as the similar but less serious conditions such as Pontiac fever and Lochgoilhead fever.

That is the scary bit. But have confidence that water supply and sources that are managed effectively are kept to very low risk.

Legionella Risk Assessments should be conducted regularly to ensure that the risk of legionella bacteria growth and spread is being properly controlled. The frequency of the assessment will depend on the level of risk in the building and the type of water system. For example, higher risk buildings such as hospitals, care homes and hotels may require more frequent assessments.

The Health and Safety Executive (HSE) recommends that a Legionella Risk Assessment is carried out at least annually. However, it may be necessary to carry out more frequent assessments if the building or water system is changed, or if there is a change in the use of the building or an outbreak of Legionnaires' disease.

Yes, it is a legal requirement to have a Legionella Risk Assessment. Under the Health and Safety at Work Act 1974 and the Control of Substances Hazardous to Health (COSHH) Regulations 2002, employers have a legal duty to assess and manage the risk of exposure to legionella bacteria in the workplace.

The specific legislation in the UK is the "The Legionnaires' disease: The control of legionella bacteria in water systems Approved Code of Practice and guidance L8" which details the requirements of the risk assessment, responsibilities and actions that need to be taken to control the risk of exposure to Legionella.

It is important to note that the responsibility for compliance with these regulations lies with the employer or person in control of the premises, whether it is a commercial or a residential building.

You can conduct a Legionella Risk Assessment yourself if you have the necessary knowledge, skills and experience to do so. However, it is important to note that if you are conducting the assessment on behalf of a business, the legal responsibility for compliance with Legionella regulations still lies with the employer or person in control of the premises.

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