How can you tell if your Legionella risk assessment is suitable?

by Charlie Brain, on 26-04-2018
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How can you tell if your Legionella Risk Assessment is suitable

In this blog we discuss the ‘Legionella risk assessment’ and whether it is suitable to comply with regulations.

What does the guidance say?

HSE guidance states:

“Carrying out a Legionella risk assessment and ensuring it remains up to date is required under health and safety law” 

The guidance suggests potential circumstances where it ceases to be “up to date”. Unfortunately, we still see instances where organisations fail to adhere to this guidance and find themselves in hot water with the HSE….

A news story on an NHS Trust fined £300,000 for not identifying a change to a water system (one of the six criteria that would trigger a water hygiene risk assessment review). The HSE stressed in their report that organisations should “review their risk control measures whenever there is reason to suspect that they are no longer valid or when there are changes to a water system”.


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Is your Legionella Risk Assessment up to date?

We’ve issued several blogs on Legionella risk assessments, where we’ve raised the “risk of not completing a Legionella Risk Assessment at the right time” and the point that risk assessments need to be reviewed regularly and should be treated as a live document.

To assist with the concept of the ‘right time’ our blog on “Risk Assessment - when do I need one?” covered reviewing and documenting. This was supported with the offer of our free risk assessment review tool as a suggestion of working out and showing which systems/buildings require a review to be undertaken. The tool takes the HSE suggested six change criteria as ‘triggers’ for when a new assessment may be required.


Is a risk assessment “suitable and sufficient”? 

To describe what is meant by “suitable and sufficient”, simply the Legionella risk assessment quality should reflect the risk of the system in question. For example, a typical domestic house maybe classed as a low risk given the limited water systems and associated volumes within the dwelling, as such the risk systems may only require a simple risk assessment resulting in simple control measures. Another way to view the detail required in the Legionella risk assessment, ‘you don’t need to use a canon to kill a mosquito’!!

Conversely, when a building becomes bigger, with more complexities associated with risk systems and the vulnerability of the occupant i.e. Cancer Care building / unit, in this instance a risk assessment that carries a degree of suitability and sufficiency, such as an accredited risk assessment that considers healthcare guidance documents, is going to very much more desired and applicable.

This table considers what may be viewed as “suitable and sufficient” in terms of guidance documents and measures of competency for varying types of buildings…

Type of Building* Documents to  be Considered Measure of Competency
Domestic House LCA Membership
School / Public Building / Office LCA Membership
Care Home

LCA Membership
UKAS Accreditation

General Healthcare
  • ACoP L8 & HSG 274
  • BS 8580
  • HTM04-01

LCA Membership
UKAS Accreditation

Immuno-compromised / Augmented Care Areas
  • ACoP L8 & HSG 274
  • BS 8580
  • HTM04-01

LCA Membership
UKAS Accreditation

* examples of buildings only – not intended to be an exhaustive list!

It is not unreasonable to suggest the systems serving the most vulnerable people to Legionella bacteria should have a Legionella risk assessment that considers all guidance documents available and be accredited. HTM04-01 details the Water Safety Groups need to be satisfied of the competency of the individual risk assessor, this can be achieved through interview.

In the experience of the Water Hygiene Centre, many Legionella risk assessments completed for healthcare buildings have not considered HTM 04-01 or BS 8580 [main claim this, although this is a throw away statement] as such are they “suitable and sufficient”?? Most probably not!

Care Homes, which are becoming more and more comparable to healthcare environments given the support and care being offered in these homes. These homes should be risk assessed against the requirements of HTM04-01. Again, in the experience of the Water Hygiene Centre Legionella risk assessments for Care Homes have not considered HTM04-1. Is this “suitable and sufficient”?


Is your Legionella risk assessment being used correctly?


The Written Scheme 

It is one thing to have a Legionella risk assessment in place, but it is what you do with it that really matters. The risk assessment is critical to the preparation of the Water Safety Plan / Written Scheme, which in turn determines the necessary monitoring regimes required in order to establish the risk systems are operated correctly and in control.

How can an organisation determine a written scheme for one of their buildings without the risk assessment in place to provide the informed status of identified risk systems?


Completing Actions and Remedial Work 

The Legionella risk assessment should also be accompanied by a risk minimisation scheme / action plan which outlines any remedial works required in order to reduce risk to as low as reasonably practicable [ALARP]. These schemes / plans need to have agreed deadlines established between the risk assessor and the organisation who commissioned the risk assessment and will be completing the mitigating works.

Failures identified by the Water Hygiene Centre with such schemes / plans, includes:

  • Deadlines set by the risk assessor with no input from the organisation, as such the deadlines can be either lenient or unachievable. This leaves the organisations open to scrutiny. Your Legionella risk assessment should only offer prioritised recommendations “ideally with an indication of timescales”, and it is up to the organisation to then consider cost and difficulty, updating the minimisation scheme accordingly.

  • The schemes / plans lack detail on risk or supporting evidence i.e. photos. These are then supported by the contractor’s price to fix the remedial works. Are these documents nothing more than a quote?? 

Closure! A sense of achievement!! Once the prioritised recommendations are actioned they need to be closed. This should be evidenced, an auditable trail that can confirm the recommendation has been completed i.e. a photograph, order / job / docket number. 



To avoid a Legionella risk assessment ‘landing you in hot water’ the assessment needs to be considered as a process and not just a document. The commissioning of a suitable and sufficient Legionella risk assessment is the start of a process. The outputs will lead to the minimisation of risk. This should then be routinely reviewed to see if any of the suggested HSE change criteria have been ‘triggered’ [see our free Risk Assessment Review Tool]

Some closing thoughts for you….

  • Do you have a Legionella risk assessment for all risk systems?

  • Is it up to date? (Consider using our free ‘risk assessment review tool’)

  • Is it suitable?

  • Has the risk minimisation scheme / action plan been formally accepted by the Water Safety Group?

  • Is the risk minimisation scheme / action plan being reviewed by the Water Safety Group and is it on schedule?

  • Can you prove completed recommendations have actually been actioned?

Further Reading: Read more about what is a legionella risk assessment, Mistakes to Avoid and Frequency >


Editors Note: The information provided in this blog is correct at date of original publication - April 2018. 

© Water Hygiene Centre 2018

Image by Ken Boyd from Pixabay 

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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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