What is a Legionella Risk Assessment? | Complete UK Guide
Legionnaire’s Risk Assessment
Legionnaire’s disease is a serious and potentially fatal form of pneumonia caused by inhaling tiny water droplets contaminated with Legionella bacteria. Any hot or cold water system can provide conditions for Legionella to grow if not properly managed, therefore a Legionella Risk Assessment is is one of the most crucial steps in identifying and controlling the risk of the legionella bacteria while remaining compliant with legislation and guidance, including COSHH, L8 ACoP and HSG274.
Whether you’re a landlord, business owner or estates or facilities manager, understanding and implementing these assessments are an extremely important step when it comes to making sure your water systems are safe to use by your staff, tenants and other people.
In this guide, we'll take you through everything you need to know about Legionella Risk Assessments, including who requires one, what’s involved and how often it should be reviewed to ensure your water systems aren’t at risk of legionnaires disease.
Contents
What is a Legionella Risk Assessment?
When is a Legionella Risk Assessment required?
Is a Legionella Risk Assessment a legal requirement?
Is Legionella Testing a legal requirement?
Who is responsible for a Legionella Risk Assessment?
What happens during a Legionella Risk Assessment?
What happens once a Legionella Risk Assessment is complete?
How often should a Legionella Risk Assessment be reviewed?
What occurs if you don’t have a Legionella Risk Assessment?
Choosing a competent Legionella Risk Assessor
1. What is a Legionella Risk Assessment?
A Legionella Risk Assessment is a detailed inspection of a property's water systems to identify conditions that could allow Legionella bacteria to grow and spread. Through highlighting the potential water safety risks, the assessment highlights the recommended actions that need to be taken to reduce levels of bacteria where required. It’s designed to prevent Legionnaires’ disease which is known for causing serious illness, with people developing symptoms that can develop from a lung infection into life threatening pneumonia.
Whilst some strains of Legionella bacteria are worse than others, Legionella pneumophila is the most severe form associated with human disease. Therefore this assessment ensures your water is safe to use and won’t make anyone unwell through preventing the presence of this harmful bacteria.
2. When is a Legionella Risk Assessment required?
A Legionella Risk Assessment is required for a number of reasons:
You have a water system in a building or workplace and need to ensure it is safe for occupants.
You own or manage properties such as offices, schools, hotels, care homes, leisure centres, warehouses or residential buildings.
You are a landlord and need to assess and control the risk of Legionella within your rental property.
You take ownership or responsibility for a new building.
A new water system has been installed.
Significant changes have been made to the water system, such as alterations to pipework, storage tanks or water heaters.
The use of the building has changed, resulting in different water usage patterns.
Parts of the building have been vacant or unused for an extended period.
Water temperatures consistently fall outside the recommended control limits.
There is evidence of stagnant water, scale, corrosion, sludge or biofilm within the system.
A previous Legionella Risk Assessment has identified actions that need reviewing.
It has been a significant period since the last assessment or review.
There has been a suspected or confirmed case of Legionnaires' disease associated with the premises.
3. Is a Legionella Risk Assessment a legal requirement?
Yes. UK health and safety legislation legally requires duty holders to assess and control the risk of Legionella bacteria where water systems could present a risk to health in their properties or businesses. Several key regulations and guidance documents underpin this requirement:
ACoP L8 ( Approved Code of Practice):
The Approved Code of Practice (ACoP) L8 is the primary guidance document for controlling Legionella bacteria in water systems. It requires employers and those responsible for premises to make sure a viable assessment is carried out to identify and assess the risk of exposure to Legionella bacteria from work activities and water systems on the premises, with potential precautionary measures needed.
Download more info here : https://www.hse.gov.uk/pubns/books/l8.htm
HSG274
HSG274 provides detailed technical guidance on how to manage and control Legionella risks in different types of water systems. It supports ACoP L8 by outlining practical measures for maintaining safe hot and cold water systems.
COSHH Regulations
The Control of Substances Hazardous to Health (COSHH) Regulations require employers and duty holders to assess risks and control exposure to hazardous substances, helping you discover where they are and how to mitigate the risks.
Health and Safety at Work Act 1974
The Health and Safety at Work Act places a duty on employers and those in control of premises to protect the health, safety and welfare of employees, visitors and other building occupants.
These regulations collectively ensure that risk assessments are not only necessary but are carried out to a high standard by an experienced specialist to protect public health.
4. Is Legionella Testing a Legal Requirement?
Whilst conducting a legionella risk assessment is a strict legal requirement, routine legionella testing is not automatically required by law. Generally you only need to test the water if the initial risk assessment flags up potential risks, the water temperature is inadequate or there is suspected bacteria. However on sites with complex water systems, particularly those with cooling towers or swimming pools, we recommend testing every 3 months.
5. Who is responsible for a Legionella Risk Assessment?
Anyone who owns, manages or is responsible for a building with a water system has a duty to assess and control the risk of Legionella bacteria. In most cases, this means carrying out a Legionella Risk Assessment to identify potential hazards and ensure appropriate control measures are in place.
Those typically responsible for a Legionella Risk Assessment include:
Landlords: Landlords of both residential and commercial properties have a legal responsibility to assess and manage the risk of Legionella within their water systems. This helps protect tenants, visitors and contractors from potential exposure to Legionella bacteria.
Business Owners: Employers and business owners must ensure that water systems within their premises do not pose a risk to employees, customers or visitors. This applies to a wide range of workplaces, including offices, hotels, gyms and hospitality venues.
Facility Managers: Facilities managers are often responsible for the day-to-day management of water systems within larger or more complex buildings. Regular Legionella Risk Assessments help ensure water systems remain compliant and properly maintained.
Duty Holders and Responsible Person:
Under UK health and safety legislation, the duty holder or responsible person is ultimately accountable for managing Legionella risks. This individual must ensure suitable assessments are carried out, risks are controlled and appropriate records are maintained.
6. What happens during a Legionella Risk Assessment?
We recommend that a competent professional inspect the entire water system and identify any factors that may encourage the growth of Legionella. Although managers and landlords are legally able to undertake a Legionella risk assessment, the necessary training, expertise, and experience are important to ensure the assessment is carried out effectively and to a high standard.
A legionella risk assessment typically includes:
Water system inspection
Reviewing areas where Legionella might grow including: cold water storage tanks, hot water systems, pipework, showers, taps, calorifiers, cooling equipment
Identifying visible risks such as stagnant water, dead legs in pipework and scale and corrosion
Testing water temperatures
Reviewing how water is stored and used
Look at existing control measures, maintenance records
Compiling a report which identifies: risk levels, required remedial works, monitoring requirements, ongoing management recommendations
7. What happens once a Legionella Risk Assessment is complete?
Once a Legionella risk assessment has been completed, the findings should be reviewed and any identified risks addressed through appropriate control measures. A competent professional will evaluate the results, determine the actions required, and oversee the implementation of measures designed to reduce the risk of Legionella proliferation within the water system.
These actions may include remedial works, system modifications, temperature control measures, the removal of dead legs or areas of stagnation, and the introduction of routine monitoring and maintenance procedures. Where necessary, a programme of regular inspections, testing, and record-keeping will also be established to demonstrate ongoing compliance and effective risk management.
8. How often should a Legionella Risk Assessment be reviewed?
The basic rule of thumb is that it's sensible to review your Legionella Risk Assessment every two years, or more frequently so it reflects the current condition and usage of your water system. There is no fixed legal requirement stating that how often you review your risk assessment, it depends entirely on the individual circumstances. ACOP simply discloses that Legionella risk assessment should be seen as a living document which must be reviewed regularly to make sure it remains up to date.
An updated risk assessment may be required if:
The water system is altered
Building usage changes - installing a new pool
Monitoring results indicate problems
Control measures fail
New guidance becomes available
A case of Legionnaires' Disease is linked to the premises
Many organisations choose to review assessments every two years as good practice, although requirements can vary depending on risk.
9. What happens if you don’t have a Legionella Risk Assessment?
Failing to assess Legionella risks can have serious consequences. These may include:
Enforcement action from the HSE
Improvement notices
Prosecution
Significant fines or reputational damage
Increased risk of Legionnaires' Disease outbreaks
Most importantly, failing to manage Legionella risks could place building occupants at risk of serious illness or even death if complications occur.
10. Choosing a Competent Legionella Risk Assessor
Not all Legionella risk assessments are equal. The quality of the assessment depends on the knowledge, experience and competence of the assessor carrying it out.
When selecting a provider, look for:
Relevant qualifications and training
Extensive industry experience
A thorough understanding of ACoP L8 and HSG274 guidance
Independent recommendations and positive client feedback
Detailed, site-specific reporting
Professional accreditations and recognised industry standards
A competent assessor will provide a clear, practical assessment tailored to your property and water system, rather than relying on generic recommendations.
At VW Compliance, our experienced assessors deliver comprehensive Legionella risk assessments that identify potential hazards, provide practical recommendations, and support ongoing compliance with current legislation and guidance. By taking a proactive approach to water hygiene management, organisations can reduce risk, protect occupants, and demonstrate their commitment to health and safety.
If you are unsure whether your property requires a Legionella risk assessment, our team can provide expert guidance and help ensure your water systems remain safe, compliant, and effectively managed.
