Legionella risk assessments: a practical guide for landlords

Landlords and building managers in the UK have a legal duty to keep water systems safe, and that includes assessing the risk of Legionella. If you’ve recently taken on a property or haven’t reviewed your water system in a while, you might be wondering where to start.

In this post, we’ll explain how to do a Legionella risk assessment, how often it should be done, and what landlords are expected to do to stay compliant.

Why Legionella matters

Legionella is a type of bacteria that can grow in water systems under the right conditions, particularly in stagnant, warm water (20–45°C). If inhaled via droplets, it can cause Legionnaires’ disease, a potentially fatal form of pneumonia.

Common places for bacteria growth include:

• Hot and cold water storage tanks
• Dead legs or unused pipework
• Shower heads, taps, and hoses
• Air conditioning and cooling towers (in larger buildings)

If you're a landlord or duty holder, you’re legally required to assess and control these risks.

How to do a Legionella risk assessment

A proper Legionella risk assessment involves inspecting the entire water system and identifying conditions that could encourage bacterial growth.

Here's a step-by-step overview:

1. Identify your water system layout

Start by understanding the full water system, where water is stored, how it flows, and where it may stagnate. This includes tanks, pipework, outlets, and any appliances connected to the system.

2. Inspect water storage

Check tanks and cylinders for cleanliness, insulation, and whether lids are securely fitted. Dirty or poorly insulated tanks are a key risk factor.

3. Measure water temperatures

Hot water should be stored at 60°C or above and distributed at a minimum of 50°C. Cold water should be below 20°C. Use a thermometer to test from outlets and storage points.

4. Look for low-use outlets and dead legs

Any taps, showers, or pipework that are rarely used or capped off can cause stagnant water, a perfect environment for Legionella.

5. Review current controls

Are outlets flushed regularly? Are records kept of maintenance and water temperature checks? If not, you may need to implement new procedures.

6. Record your findings

You should document your assessment, even if the property is low-risk. This includes potential hazards, control measures in place, and recommendations.

If you're unsure at any stage, a qualified provider can carry out a professional legionella risk assessment for landlords and help put a plan in place.

How long does a Legionella risk assessment last?

There’s no fixed expiry date, but a general rule of thumb is:

• Every 2 years for low-risk residential settings
• Annually for higher-risk systems or commercial premises
• Immediately after changes to the water system, occupancy, or building use

You should also review the assessment if there's been a water system failure, a period of non-use (e.g. student housing during holidays), or if new tenants raise water-related concerns.

The key is to treat the assessment as a living document, something to be reviewed and updated when conditions change.

Do landlords always need to test the water?

Contrary to popular belief, water testing is not always required. In most domestic or low-risk settings, physical testing (i.e. water sampling) isn't needed unless the system shows signs of potential risk.

Instead, landlords should focus on:

• Maintaining safe hot and cold water temperatures
• Flushing out infrequently used outlets
• Cleaning shower heads regularly
• Ensuring tanks and pipes are in good condition
• Keeping a record of checks and maintenance

However, in some commercial or multi-unit buildings, water sampling may be part of your ongoing control measures.

Can landlords do the risk assessment themselves?

Yes, but only if you’re competent. For small, simple systems (like single-let residential properties), landlords can carry out the risk assessment themselves, provided they understand the risks and control measures.

That said, for larger or more complex buildings, such as HMOs, care homes, or commercial premises — it’s best to use a professional service.

A qualified engineer can identify hidden risks and help set up a robust Legionella control regime.

If you need help, our legionella risk assessment for landlords covers both domestic and commercial systems and includes full reporting, guidance, and follow-up.

What happens if you don’t comply?

Failing to carry out a Legionella risk assessment can lead to serious consequences:

• Legal action or fines under the Health and Safety at Work Act
• Prosecution if someone becomes ill or is exposed to risk
• Loss of rental licence or insurance issues for landlords
• Reputational damage for property managers

Even if you believe your system is low-risk, doing an assessment and keeping a record shows that you’ve taken your responsibilities seriously.

Final thoughts

Legionella risk assessments are a legal requirement, and more importantly, a crucial part of keeping tenants and building users safe. Whether you manage a single property or a full portfolio, understanding how to do a Legionella risk assessment and knowing when to update it is essential.

If you’re unsure where to start or want peace of mind that everything’s covered, reach out to a trusted provider. A professional legionella risk assessment for landlords is the easiest way to stay compliant and protect your people.

Book your Legionella risk assessment

We offer professional Legionella assessments for landlords, letting agents, and facilities managers across London and the South East. Whether it's your first time or a regular review, we’ll guide you through every step.

Schedule your Legionella risk assessment today

References

LegionellaControl.com – How Often Should You Do a Legionella Risk Assessment?

HSQE Consultancy – How Often Should a Legionella Assessment Be Performed Legally?