Legionella Risk Assessments for Landlords: What You Need to Know

A Duty Most Landlords Overlook

When private landlords in England think about safety compliance, gas and electrical certificates usually come to mind first. Legionella risk assessments, by contrast, are frequently forgotten or dismissed as something that only applies to large commercial buildings.

That is a mistake. The Health and Safety Executive (HSE) is clear: landlords of residential properties in England have a legal duty to assess the risk of legionella exposure to their tenants. Whilst the risk in most domestic properties is low, the assessment itself is a legal obligation — and failing to carry one out leaves you exposed.

The risk of legionella in a typical domestic property is low. But the requirement to assess that risk is not optional — it is a legal duty under the Health and Safety at Work Act.

What Is Legionella?

Legionella is a type of bacteria that can grow in water systems, particularly where water is stored at temperatures between 20°C and 45°C. If contaminated water is dispersed as a fine mist or aerosol (for example, through a shower head), the bacteria can be inhaled and cause Legionnaires' disease — a serious and potentially fatal form of pneumonia.

Conditions That Encourage Legionella Growth

• Water stored at temperatures between 20°C and 45°C
• Stagnant water in pipes, tanks, or dead legs (unused sections of pipework)
• Scale, rust, or sediment that provides nutrients for bacteria
• Systems that produce aerosols (showers, spa baths, certain taps)

The Risk in Domestic Properties

For most standard rental properties with a combi boiler and no stored water, the risk is low. The hot water is heated on demand and does not sit in a tank, reducing the conditions in which legionella can thrive.

The risk increases where:

• The property has a hot water storage tank or cylinder
• There are long runs of pipework with infrequent use
• Shower heads or taps have not been cleaned or descaled
• The property has been empty for an extended period (void periods) — something landlords who self-manage their properties must be especially mindful of

Your Legal Obligations

The Legal Basis

The duty to assess legionella risk comes from the Health and Safety at Work etc. Act 1974 and the Control of Substances Hazardous to Health Regulations 2002 (COSHH). The HSE's Approved Code of Practice L8 provides detailed guidance.

What You Must Do

As a landlord, you are the "duty holder" responsible for:

• Assessing the risk of legionella in your property's water system
• Implementing control measures where risks are identified
• Keeping records of the assessment and any actions taken
• Reviewing the assessment periodically — this forms part of your broader landlord responsibilities for repairs and maintenance

How to Carry Out a Legionella Risk Assessment

For most standard domestic rental properties, the assessment does not require specialist equipment or laboratory testing. It is a systematic review of the water system to identify and manage risks.

What the Assessment Covers

1. Identify the water systems. Document how hot and cold water is supplied to the property. Note whether there is a combi boiler (low risk) or a hot water storage cylinder/tank (higher risk). Identify all outlets — taps, showers, outside taps.
2. Check water temperatures. Hot water should be stored at 60°C or above and delivered at taps at 50°C or above within one minute. Cold water should be below 20°C. These temperatures inhibit legionella growth.
3. Look for potential risks. Dead legs (unused sections of pipe), infrequently used outlets, and areas where water can stagnate are the primary concerns. Also check for scale, corrosion, or biofilm in the system.
4. Assess the risk level. For a standard property with a combi boiler and regularly used outlets, the risk is typically low. For a property with stored water, long pipe runs, or infrequently used outlets, the risk may be moderate and require control measures.
5. Identify control measures. Common measures include setting the hot water thermostat to at least 60°C, running infrequently used taps weekly, descaling and cleaning shower heads regularly, and insulating cold water pipes to prevent warming.
6. Record your findings. Document the assessment, the risks identified, and the control measures in place or implemented. Keep this record with your property's compliance files.

Can You Do It Yourself?

For a straightforward domestic property, yes. The HSE does not require a specialist to carry out the assessment in most cases. However, if you are not confident in identifying the components of the water system or assessing the risks, instructing a professional is a sensible investment. A professional legionella risk assessment for a domestic property typically costs £50-£150.

Control Measures for Common Situations

Properties With Hot Water Cylinders

• Set the cylinder thermostat to at least 60°C
• Ensure hot water reaches outlets at 50°C within one minute
• Consider whether the tank size is appropriate for the property's usage — an oversized tank with low usage increases risk
• Insulate the cylinder to maintain temperature

Properties Left Vacant (Void Periods)

When a property is empty between tenancies, water can stagnate throughout the system.

• Before a new tenancy: Run all taps and showers for at least two minutes to flush the system
• During extended voids: Consider visiting the property weekly to flush outlets, or drain the system down entirely if the void will be longer than a month

Shower Heads and Taps

• Clean and descale shower heads at least every three months (or instruct the tenant to do so)
• Replace shower heads that cannot be adequately cleaned
• Ensure spray taps are cleaned regularly

Record-Keeping

Good records protect you. If a tenant were to develop Legionnaires' disease, the first question from the HSE would be whether you carried out a risk assessment and what control measures were in place.

What to Record

• Date of the assessment
• Who carried it out (you or a professional)
• Description of the water system
• Risks identified
• Control measures in place
• Any actions taken or recommendations for follow-up
• Date of next review

How Long to Keep Records

There is no statutory retention period specified for legionella risk assessments, but best practice is to keep them for at least five years and retain the most recent assessment indefinitely while you own the property.

Tenant Responsibilities

You can — and should — provide tenants with simple guidance on their role in legionella prevention:

• Do not adjust the hot water thermostat below 60°C
• Run any taps or showers that are not used regularly at least once a week
• Clean and descale shower heads periodically
• Report any problems with the hot water system promptly
• Inform you if the property will be unoccupied for an extended period

The Bottom Line

A legionella risk assessment for a standard rental property is not a major undertaking. For most properties, it takes less than an hour and confirms what you probably already know — the risk is low. But having the assessment documented protects you legally and demonstrates that you are a responsible landlord who takes tenant safety seriously. It also supports compliance with the Property Portal registration requirements coming to England.

Further Reading

• Gas Safety Certificate: Landlord Guide for 2026 — another essential annual safety check for landlords in England
• Smoke and Carbon Monoxide Alarm Regulations for Landlords — keeping your property compliant with alarm requirements
• Fire Safety Regulations for Rental Property — the full fire safety obligations for private landlords