Legionella Risk Assessment

We provide Legionella Risk Assessment and Legionella Water Testing Services through our Expert Fully Qualified Legionella Services Partner.


Contact us for a quotation. 


Our partner is a full Member of the Water Management Society, and holds a City in Guilds and WMSoc accredited qualification in Practical Legionella Risk Assessment. They also have following memberships and accreditations that ensure their work is both safe, compliant and technically correct. CHAS accreditation, Safe Contractor accreditation and they are members of the Legionella Control Association and BSRIA.

Our partner for Legionella services is fully qualified and conducts Legionella Risk Assessments that are fully compliant with HSE legislation.

The Legionella Risk Assessment Includes:


• An executive summary of your water system, along with a clear overall risk rating system.
• A detailed audit framework for both the management system and control scheme, highlighting hazards.
• A comprehensive recommendations guide that covers site remedial works and water management recommendations.
• Listing of Assets, outlets, sentinel points and dead legs comprehensively, providing further clarity through risk evaluation and risk exposure survey.

Our partner can also provide a microbiological testing service for Legionella. Microbiological sampling and testing utilising a UKAS accredited Laboratory.


Legionella Risk Assessment

What is Legionella?


Legionella is a type of water-borne bacteria that can be found often in harmlessly low numbers in ponds, rivers and lakes. However, the bacteria can rapidly multiply to harmful quantities if they find their way into purpose-built systems where water is maintained at a temperature high enough to encourage growth, e.g. cooling towers, evaporative condensers, hot and cold water systems and spa pools used in all sorts of premises (work and domestic).

There are over 40 different species of legionella bacteria. However, legionella pneumophila is considered the most dangerous as it causes about 90% of the cases of infection. Around 16 different sub groups of legionella pneumophila have been reported as the cause of infection. However, Legionella Pneumophila Serogroup 1 is the most associated with Legionnaires’ disease in the UK.

The two things that Legionella bacteria need to grow and reproduce are:

– a water temperature of 20-45C (68-113F)
– impurities in the water that can support bacterial growth providing a source of nutrients for the organism e.g. rust, sludge, scale, organic matter and biofilms


What is Legionnaires’ Disease?


Legionnaires’ disease is a serious lung infection caused by Legionella bacteria. People contract Legionnaires’ disease by inhaling small droplets of water (aerosols), suspended in the air, containing the Legionella bacteria. The infection isn’t contagious and can’t be spread directly from person to person. Once bacteria begin to infect your lungs, you may also experience symptoms of pneumonia. In some cases, Legionnaires’ disease can lead to further, life-threatening problems. Severe infection can cause some organs, such as your lungs or kidneys, to stop working properly. Another complication is septic shock. An estimated 10% of otherwise healthy people who develop Legionnaires’ disease die due to problems like these.
More info about Legionnaires’ disease here: www.nhs.uk/Conditions/Legionnaires-disease/Pages/Introduction.aspx 


What does the Law require for Legionella Risk Assessment?


It is a legal requirement to conduct a legionella risk assessment according to HSE Document; Approved Code of Practice L8:2013

On p11, point 28 it is stated that:
‘A suitable and sufficient assessment must be carried out to identify and assess the risk of exposure to legionella bacteria from work activities and water systems on the premises and any precautionary measures needed. The dutyholder is responsible for ensuring the risk assessment is carried out. The dutyholder is either: (a) the employer, where the risk from their undertaking is to their employees or others; or (b) a self-employed person, where there is a risk from their undertaking to themselves or others; or (c) the person who is in control of premises or systems in connection with work, where there is a risk from systems in the building, eg where a building is let
to tenants, but the landlord keeps responsibility for its maintenance.’

Point 29 states that:
‘The dutyholder must ensure that the person who carries out the risk assessment and provides advice on prevention and control of exposure must be competent to do so.’
‘A competent person is someone with the necessary skills, knowledge and experience to manage health and safety, including the control measures.’
www.hse.gov.uk/legionnaires/faqs.htm – ‘Risk Assessment’


What does a Legionella Risk Assessment need to Include?


On their website the HSE state that:
‘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.’
www.hse.gov.uk/legionnaires/faqs.htm – ‘Risk Assessment’

Legionella Risk Assessment Plumbing

Is Water Testing for Legionella needed and How Often?


Water testing for legionella is not always needed. It depends on the type of building, type of water system and the findings from the legionella risk assessment.
On their website the HSE state the following:
‘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, i.e. 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’
www.hse.gov.uk/legionnaires/faqs.htm – ‘Testing/monitoring Legionella’


How Often Should a Legionella Risk Assessment be Completed?


‘The record of the assessment is a living document that must be reviewed to ensure it remains up-to-date. Arrange to review the assessment regularly and specifically whenever there is reason to suspect it is no longer valid. An indication of when to review the assessment and what to consider should be recorded. This may result from, e.g.:

(a) changes to the water system or its use;
(b) changes to the use of the building in which the water system is installed;
(c) the availability of new information about risks or control measures;
(d) the results of checks indicating that control measures are no longer effective;
(e) changes to key personnel;
(f) a case of legionnaires’ disease/legionellosis associated with the system.’

Page 14 Para 47 www.hse.gov.uk/pubns/books/l8.htm

The legionella risk assessment should be audited regularly. The frequency of auditing, like all other elements of the legionellosis control strategy, is risk assessment based and guidance is exactly that, guidance. Well maintained and controlled systems may not generate much for an auditor to comment on in the course of a year, whilst another operating to a lower standard or having a high turnover of staff may have lots of issues that when trended suggest that a risk assessment review is required. The Legionella Control Association (LCA) recommend an annual audit frequency, and this is a good starting point which is generally applicable, but should not be confused with a review, which should be prompted by any significant change in system, operation, personnel etc. (para 47 above)

 Further information to inform you about Regulation and Guidance for Legionella Testing:


– COSHH, regulations 7 and 9; HSW Act, sections 2, 3 and 4.
These Regulations require employers to prevent, or where this is not reasonably practicable, adequately control, the exposure of any employees to substances hazardous to health. Employers are also required to maintain, examine and test control measures and, at suitable intervals review and, if necessary, revise those measures. They must also keep suitable records of examinations, tests and repairs of control measures.

– ACOP L8 – The control of legionella bacteria in water systems (para 61 & 67 – 68) states. ‘Once the risk has been identified and assessed, a written scheme should be prepared for preventing or controlling it’. The written scheme information about the water system and the associated risk of exposure. If it is decided that the risks are insignificant and effectively managed in compliance with the law, then there may be no need for further action.
‘It is important to review the risk assessment regularly and specifically if there is reason to suspect it is no longer valid, for example changes in the water system or its use’. The primary focus should be avoiding conditions in which legionella bacteria can colonise and multiply, alongside the avoidance where possible of the creation of spray or aerosols. ‘Testing of water quality is an essential part of the treatment regime’. This can be carried out by service providers, water treatment companies, consultants or by the operator (subject to training and proper supervision). The test requirements depend on the water system.

Routine monitoring of bacteria levels is an important indication of whether control is being achieved. Risk Assessment will enable the identification of the appropriate monitoring for the system. Reliable testing for Legionella is technically difficult and will require specialist laboratory facilities. Interpretation can also be complex, negative results are not a guarantee of a legionella free system and positive results are not always indicative of a failure of control. Legionella are present in almost all natural water sources. Further guidance can be found at


A suitably experienced and competent person should interpret the results of monitoring and testing, carrying out any remedial measures promptly, where needed.

Microbiological monitoring of domestic hot and cold water supplied from the mains is not usually required, unless the risk assessment or monitoring indicates there is a problem. Legionella monitoring should be carried out where there is doubt about the efficacy of the control regime or it is known that recommended temperatures, disinfectant concentrations or other precautions are not being consistently achieved throughout the system.

Where monitoring for legionella is considered appropriate in hot and cold water systems, sampling should be carried out in accordance with BS 7592 – Sampling for legionella organisms in water. The complexity of the system will need to be considered to determine the appropriate number of samples to take. To ensure the sample is representative of the water flowing around the system and not just of the area downstream of the fitting, samples should be taken from separate hot and cold outlets rather than through mixer taps or outlets downstream of TMVs or showers. Samples should be clearly labelled with their source location and if collected pre- or post-flushing.

In both hot and cold water systems, samples should be taken, if considered necessary by the risk assessment. There should be a focus on areas where the target control parameters are not met i.e. where disinfectant levels are low or where temperatures are below 50 °C (55 °C in healthcare premises) for Hot water systems or exceed 20 °C for cold water systems. Also, areas subject to low usage, stagnation, excess storage capacity, dead legs, excessive heat loss, crossflow from the water system or other anomalies.

In cold water systems, samples should also be taken as required from the point of entry (or nearest outlet) if the water is supplied from a private water supply or where the temperature of the incoming mains supply is above 20 °C from the cold water storage tank or tanks. Samples should also be taken from the furthest and nearest outlet on each branch of the system (far and near sentinel outlets).

In hot water systems, samples should also be taken as required from the calorifier hot water outlet and from the base of the calorifier (if it safe to do so, as some systems are under considerable pressure), from the furthest and nearest outlet on each branch of a single pipe system (far and near sentinel outlets) and from the furthest and nearest outlet on each loop of a circulating system (far and near sentinel outlets).

Our specialist Legionella partner has checked this information as of Nov 2017 but if you have any questions about Legionella please email info@safesmart.co.uk and our partner will then get in touch with you directly.


Use the form below to book a Legionella Risk Assessment and/or Legionella Water Testing 



Safesmart LTD

1 Warren Yard
Warren Park
Stratford Road
Milton Keynes
MK12 5NW

T: 08701 273 999
T: 01908 320 152
E: info@safesmart.co.uk