Legionella Risk Assessments 
 

Who can undertake the risk assessment for legionella?

As an employer or a person in control of premises, you must appoint person or persons responsible for helping you manage your health and safety duties, eg take responsibility for managing risks. A competent person is someone with the necessary skills, knowledge and experience to manage health and safety, including the control measures. You could appoint one, or a combination of:

• yourself

• one or more workers

• someone from outside your business

If you decide to employ contractors to carry out your risk assessment or other work, it is still the responsibility of the competent person to ensure that the work is carried out to the required standards. Remember, before you employ a contractor, you should be satisfied that they can do the work you want to the standard that you require.

How do I carry out a Legionella risk assessment?

The purpose of carrying out a risk assessment is to identify and assess any risks in your water system. The responsible person should understand your water systems and any associated equipment, in order to conclude whether the system is likely to create a risk from exposure to legionella, and should be able to identify whether:

• water is stored or re-circulated as part of your system

• the water temperature in some or all parts of the system is between 20–45 °C

• there are sources of nutrients such as rust, sludge, scale and organic matters

• conditions are present to encourage bacteria to multiply

• it is possible for water droplets to be produced and, if so, whether they could be dispersed over a wide area, eg showers and aerosols from cooling towers

• it is likely that any of your employees, residents, visitors etc are more susceptible to infection due to age, illness, a weakened immune system etc and whether they could be exposed to any contaminated water droplets

Your risk assessment should include:

management responsibilities, including the name of competent person and a description of your system;

• potential sources of risk;

• any controls in place to control risks;

• monitoring, inspection and maintenance procedures;

• records of the monitoring results, inspections and checks carried out;

• arrangements to review the risk assessment regularly

If you decide that the risks are insignificant, your assessment is complete. You may not need take any further action at this stage but you should review the assessment regularly in case anything changes in your system.

If I am not storing hot or cold water in my system, do I need to carry out a risk assessment?

Yes. There may be other factors within your system that increase the risks of legionellosis, eg deadlegs, showerheads and/or long runs of pipe work containing warm water. A risk assessment should also consider anyone who could be potentially exposed to any legionella bacteria in your system, and particularly groups that are at a higher risk of contracting legionellosis. However, once you have completed your risk assessment you may decide that the risks are insignificant. If you do, you need take no further action other than to review the assessment regularly in case anything changes in your system.

How do I control the risks from legionella in my water system?

The key point is to design, maintain and operate your water services under conditions that will either prevent or adequately control the risk from legionella bacteria. It is important that you either have, or have access to, competent help to fulfil these obligations.

If you identify a risk that you are unable to prevent, you must introduce appropriate controls. You should introduce a course of action that will help you to control any risks from legionella by describing:

• your system and its component parts eg developing a schematic diagram

• who is responsible for carrying out the assessment and managing its implementation

• the safe and correct operation of your system

• what control methods and other precautions you will be using

• what checks will be carried out to ensure risks are being managed and how often

You should where appropriate:

• ensure that the release of water spray is properly controlled

• avoid water temperatures and conditions that favour the growth of legionella and other micro-organisms

• ensure water cannot stagnate anywhere in the system by keeping pipe lengths as short as possible or by removing redundant pipe work

• avoid materials that encourage the growth of legionella (The Water Fittings and Materials Directory references fittings, materials, and appliances approved for use on the UK Water Supply System by the Water Regulations Advisory Scheme)

• keep the system and the water in it clean

• treat water to either control the growth of legionella (and other microorganisms) or limit their ability to grow

Find out more about what is Legionnaires' Disease is.

Who can be appointed to test or monitor legionella?

Testing of water quality may be carried out by a service provider, such as a water treatment company or consultant, or by the operator, provided they are trained to do so and are properly supervised. The type of test required will depend on the nature of the water of the system. HSG274 Legionnaires' disease Technical guidance provides further details for both evaporative cooling systems and hot and cold water systems.

How do I test or monitor legionella from my water system?

Where monitoring for legionella is considered appropriate, the sampling method should be carried out in accordance with BS7592 and the biocide, if used, neutralised where possible. Water samples should be tested by a UKAS-accredited laboratory that takes part in a water microbiology proficiency testing scheme such as that run by Public Health England. The laboratory should also apply a minimum theoretical mathematical detection limit of <= 100 legionella bacteria per litre of sample for culture-based methods.

How often should I test water for Legionella?

It depends on the system that you have and the outcome of your risk assessment. For open systems, such as cooling towers, evaporative condensers and spa pools etc, routine testing should be carried out at least quarterly. However, there may be circumstances were more frequent sampling may be required.

For hot and cold water systems, which are generally enclosed, ie not open to the elements and significant contamination in the same way as cooling towers, microbiological monitoring is not usually required. But there may be circumstances where testing for legionella is necessary eg where there is doubt about the efficacy of the control regime or where recommended temperatures or disinfection concentrations are not being consistently achieved. Further guidance is available in HSG274 Part 2 (PDF)

How do I interpret legionella test results?

Consider what the results mean in the context of your water system. Your subsequent specific actions will depend on your risk assessment. Further information about what action to take when certain levels of legionella are identified can be found in HSG274 Part 1 (paras 1.114 – 1.129 and table 1.10) for evaporative cooling systems (PDF) ; and HSG274 Part 2 (paras 2.119 – 2.125 and table 2.2) for hot and cold water systems (PDF) .

Is it necessary to clean and disinfect my water system?

It is important to maintain the cleanliness of your water system. The mechanisms and frequency for doing this will depend on the system you have and whether cleaning or disinfecting is being done routinely or because of a problem identified during monitoring. The frequency and method of routine cleaning and disinfecting should be identified within your risk assessment. This will take account of factors such as whether the system is open or closed, the type and level of contamination, and the population that could be exposed.

Who can be appointed as the 'responsible' person?

The responsible person will take day-to-day responsibility for managing the control of any identified risk from legionella bacteria. Anyone can be appointed as the responsible person as long as they have sufficient authority, competence, skills and knowledge about the installation to ensure that all operational procedures are carried out in a timely and effective manner and implement the control measures and strategies, ie they are suitably informed, instructed, trained and assessed.

They should be able to ensure that tasks are carried out in a safe, technically competent manner. If a dutyholder is self-employed or a member of a partnership, and is competent, they may appoint themselves. The responsible person should be suitably informed, instructed and trained and their suitability assessed. They should also have a clear understanding of their duties and the overall health and safety management structure, and policy in the organisation.

An automated temperature monitoring system is a digital solution that continuously tracks water temperatures in real time using sensors. It replaces manual checks with accurate, automated data collection to help maintain compliance and reduce risks such as Legionella.

Residential Properties & Similar:

Where the system is relatively simple, the assessment itself won't take very long to complete. We still need to process and quality check the document before sending it to you.

Individual cost £125 + VAT

Multiple properties (i.e. more than 5) £75 + VAT

Commercial Properties, Offices, Doctors/Dental Surgeries & Similar:

These systems that are slight more complex in that there are more water outlets and areas to assess will take more time on site to complete.

Estimated Cost £325 + VAT - please contact us if you have multiple sites as our costs per premises will be less.

Schools, Colleges, Universities, Hospitals and Other Healthcare Premises:

These bigger and more complex sites require an individual estimate being supplied due to the range in sizes and numbers of buildings. Please contact us via phone or our contact form to receive a quotation.

Please contact us using our number or contact form to get an accurate quote.