Understanding Your Legal Duties for Legionella Control in UK Properties

If you own, manage, or rent out a property in the UK, there’s a legal responsibility you may not realise you have, and it sits quietly inside your water system.

Legionella bacteria can grow in hot and cold water systems and, if left unmanaged, can lead to Legionnaires’ disease, a serious and potentially fatal form of pneumonia. Because of this risk, UK law places clear duties on landlords, employers, and duty holders to carry out a Legionella risk assessment and put suitable Legionella control measures in place.

Yet many people are still unsure what is actually required, what the law says, and whether Legionella testing is mandatory.

This guide breaks it down in plain English, so you understand exactly where you stand and what you must do to stay compliant.

What Is Legionella and Why Risk Assessments Matter

Legionella is a naturally occurring bacterium found in water. It becomes a health risk when it multiplies in man-made water systems, such as:

• Hot and cold water tanks
• Pipework
• Showers and taps
• Cooling towers
• Spa pools

The bacteria spread through tiny water droplets (aerosols) that can be inhaled. This is how people contract Legionnaires’ disease.

A Legionella bacteria risk assessment is designed to identify whether your water system could allow this bacteria to grow and spread, and what needs to be done to prevent it.

In simple terms, a Legionella risk assessment is a specific type of water hygiene risk assessment and water risk assessment focused on preventing this exact hazard.

UK Law and Legionella Risk Assessments

Legionella control is not just “best practice”. It is a legal requirement under several pieces of UK legislation:

• Health and Safety at Work etc. Act 1974
• Control of Substances Hazardous to Health (COSHH) Regulations
• Management of Health and Safety at Work Regulations
• HSE Approved Code of Practice L8 (ACOP L8)
• HSG274 guidance

Together, these regulations require duty holders to assess and control the risk of exposure to Legionella bacteria.

This is where the HSE Legionella risk assessment requirement comes from.

Who Has a Legal Duty to Carry Out a Legionella Risk Assessment?

You are legally responsible if you are:

• A landlord (private or commercial)
• An employer
• A building owner
• A facilities manager
• A managing agent
• Anyone in control of premises (known as the “duty holder”)

Yes, this includes domestic landlords.

Many landlords wrongly assume Legionella rules only apply to hospitals or large commercial buildings. In reality, even a single rental property with a hot water cylinder and pipework must have a Legionella risk assessment.

Landlords and Legionella: Clearing Up Common Confusion

One of the biggest areas of confusion is the difference between a Legionella risk assessment and Legionella testing.

Here’s what the HSE makes clear:

You must carry out a risk assessment.

You are not automatically required to carry out legionella testing.

This surprises many landlords.

For most standard domestic properties with simple water systems, the law requires you to:

1. Assess the risk
2. Identify if control measures are needed
3. Record your findings

Routine legionella water testing is only required where the risk assessment shows it is necessary, for example, in more complex systems or where control measures need verification.

This is why a professional water hygiene risk assessment is so important. It tells you what you actually need to do, rather than guessing.

What Is a Legionella Risk Assessment? (And What Does It Involve?)

A proper Legionella risk assessment is far more than a quick visual check.

A competent assessor will:

1. Identify Potential Hazards

• Areas where water can stagnate
• Dead legs in pipework
• Infrequently used outlets
• Inadequate temperatures

2. Assess Who Is at Risk

• Tenants
• Staff
• Visitors
• Vulnerable individuals (elderly, smokers, those with health conditions)

3. Examine the Water System

• Tanks
• Cylinders
• Pipe runs
• Showers and taps
• Storage temperatures

4. Measure Water Temperatures

Legionella thrives between 20°C and 45°C. Proper control depends heavily on temperature management.

5. Recommend Control Measures

• Flushing regimes
• Temperature adjustments
• Tank cleaning
• Removal of dead legs
• Monitoring requirements

6. Provide a Written Record

This document is your legal evidence of compliance.

This is what the law means by a Legionella bacteria risk assessment.

Legionella Testing: What, When and Why

Many people search for Legionella test or Legionella water testing, believing it is a legal requirement. In most cases, it isn’t.

However, testing is often recommended when:

• The system is complex
• The property is high risk (care homes, healthcare, hotels)
• Control measures need to be verified
• There has been previous contamination
• Water temperatures cannot be reliably maintained

Testing is a tool, not the starting point. The water risk assessment determines whether testing is needed.

How Often Should Legionella Risk Assessments Be Reviewed?

There is no fixed time period written into law. However, the HSE guidance is clear that reviews should take place:

• When there are changes to the water system
• When the building use changes
• If there is reason to suspect it is no longer valid
• Periodically, as good practice (commonly every two years)

This is why you’ll often hear professionals refer to Legionella risk assessments needing regular review.

A report is not a one-time document. It’s part of ongoing Legionella control.

Record Keeping: Your Legal Protection

If the HSE ever investigates, the first thing they will ask for is documentation.

You should be able to show:

• Your Legionella risk assessment
• Records of any actions taken
• Temperature monitoring (if required)
• Flushing records (if required)
• Any Legionella testing results (if undertaken)

Without records, it is very difficult to prove you have met your legal duty, even if you have.

Common Mistakes People Make

These are the issues professionals see time and time again:

• Assuming domestic properties are exempt
• Thinking that a plumbing check counts as a risk assessment
• Paying for unnecessary Legionella testing without a risk assessment
• Filing the report away and never reviewing it
• Not keeping evidence of control measures

All of these can lead to non-compliance.

Why Professional Help Matters

While the law allows landlords to carry out their own water risk assessment, the HSE also states that the person must be competent.

Competence means understanding:

• Water systems
• Legionella growth factors
• Legal guidance (ACOP L8 & HSG274)
• Appropriate control measures

This is why many landlords, managing agents, and businesses choose to use specialists like L8 Protection.

How L8 Protection Can Help

At L8 Protection, Legionella control is what we do every day.

We provide:

• Fully compliant Legionella risk assessments
• Clear, practical action plans
• Support with ongoing water hygiene risk assessment and monitoring
• Advice on whether Legionella testing is actually required
• Ongoing compliance support and reviews

Our assessments don’t just tick a box; they give you confidence that your property, tenants, and business are protected and legally compliant.

Book Your Legionella Risk Assessment with L8 Protection

If you’re unsure whether your property is compliant, or you know your Legionella risk assessment is overdue, now is the time to act.

Legionella control is a legal duty, not a box-ticking exercise. Having a clear, up-to-date Legionella risk assessment in place protects your tenants, your staff, your visitors, and your legal position.

At L8 Protection, we make the process straightforward. Our specialists carry out fully compliant assessments, explain exactly what (if anything) you need to do next, and support you with practical, sensible guidance,  without unnecessary testing or costs.

Whether you manage a single rental property, multiple sites, or commercial premises, we’re here to help you stay safe and compliant.

Get in touch with L8 Protection today to schedule your Legionella risk assessment and take the uncertainty out of Legionella control.