Do landlords legally need a Legionella risk assessment?

Yes. Under the Health and Safety at Work Act 1974 and the Control of Substances Hazardous to Health Regulations 2002 (COSHH), anyone who provides residential accommodation has a legal duty to assess the risk of Legionella exposure. The HSE's Approved Code of Practice L8 makes clear this applies to landlords of all sizes, including those with a single rental property.

How often should a Legionella risk assessment be done on a rental property?

The HSE recommends reviewing the assessment every 2 years, or sooner if there is a change in the water system, a change of tenancy, or a reason to believe the assessment is no longer valid. Many letting agents reassess at every new tenancy as a matter of best practice.

How much does a Legionella risk assessment cost?

A standard assessment for a domestic rental property typically costs £50–£150, depending on the property size and location. Properties with complex water systems — such as HMOs with header tanks or stored hot water — may cost £150–£300. Remedial work, if needed, is charged separately.

Can a landlord do their own Legionella risk assessment?

Technically, yes — the HSE does not require you to use an external assessor for simple domestic properties. However, you must be competent to carry out the assessment. For most landlords and letting agents, instructing a qualified water hygiene company is the safest approach because it provides a documented, defensible record if anything goes wrong.

What is the fine for not having a Legionella risk assessment?

There is no fixed penalty notice. Instead, the HSE can prosecute under the Health and Safety at Work Act, which carries an unlimited fine and up to 2 years' imprisonment for serious breaches. If a tenant contracts Legionnaires' disease due to landlord negligence, the landlord can face both criminal prosecution and civil claims for damages.

Legionella Risk Assessment for Rental Properties: What UK Landlords and Letting Agents Must Do

Why Legionella matters for rental properties

Legionella is a bacteria that grows in stagnant or lukewarm water. When inhaled as fine droplets — from a shower, tap, or even a garden hose — it can cause Legionnaires' disease, a severe form of pneumonia that kills roughly 10% of those infected.

Rental properties are particularly at risk because:

Void periods leave water sitting in pipes and tanks for weeks or months
Tenants may be away for holidays or hospital stays, reducing water flow
Communal systems in HMOs serve multiple outlets with complex pipework
Older properties are more likely to have dead legs, unused taps, or corroded tanks

This is not a hypothetical problem. The HSE investigates Legionella outbreaks every year, and landlords have been prosecuted for failing to manage the risk.

The legal duty

There is no single "Legionella Act." Instead, the duty sits across several overlapping pieces of legislation:

Health and Safety at Work Act 1974 — creates a general duty to ensure, so far as reasonably practicable, the health and safety of people who may be affected by your work activity. Letting property is a work activity.
COSHH Regulations 2002 — require you to assess and control risks from hazardous substances, including biological agents like Legionella.
HSE Approved Code of Practice L8 — "Legionnaires' disease: The control of legionella bacteria in water systems." This is the practical standard. It explicitly states that landlords of domestic rental properties must assess the risk of Legionella in their water systems.
HSG274 Part 2 — the HSE's technical guidance for hot and cold water systems, covering temperature control, flushing, and monitoring.

The key point: you do not need a tenant to become ill before you are in breach. The duty is to assess and manage the risk. Failing to have an assessment at all is the offence.

What about letting agents?

If you manage properties on behalf of a landlord, the management agreement usually makes you responsible for arranging safety checks — including Legionella. Check your agreement. If it is silent on Legionella, you should clarify in writing who is responsible, because the HSE can pursue whoever has day-to-day control of the property.

What a Legionella risk assessment covers

A competent assessor will inspect the property and evaluate:

Water system layout

Where water enters the property (mains supply or stored water)
Whether there is a cold water storage tank (common in older properties)
Type of hot water system (combi boiler, unvented cylinder, vented cylinder with header tank)
Any dead legs — sections of pipework that are capped off or connected to removed appliances

Temperature control

Cold water should be stored and distributed below 20°C
Hot water should be stored at 60°C or above and distributed at 50°C or above at the outlet within one minute
The danger zone for Legionella growth is 20°C to 45°C — water sitting in this range is the primary risk

Water usage and stagnation

Are all outlets used regularly?
Are there any taps, showers, or cisterns that are rarely or never used?
How long is the property typically void between tenancies?

Other risk factors

Condition of showerheads (biofilm buildup)
Scale, rust, or sediment in the system
Presence of a thermostatic mixing valve (TMV)
External water features (hot tubs, garden hoses with spray attachments)

The output is a written report grading the overall risk as low, medium, or high, with specific recommendations. For most domestic rental properties, the risk is low and the required actions are simple.

What you need to do in practice

For the majority of rental properties — a house or flat with a combi boiler and no stored cold water — the risk is low and the actions are straightforward:

For every property

1Get a Legionella risk assessment before the first tenancy, and review it every 2 years or at each change of tenancy
2Keep the hot water temperature at 60°C or above at the cylinder (if applicable) — combi boilers heat on demand and are inherently lower risk
3Remove or regularly flush any dead legs — if a tap or outlet has been capped off, either remove the pipework back to the main run or flush it weekly
4Clean and descale showerheads at least quarterly — or instruct tenants to do so in the tenancy agreement
5Flush the system during void periods — run all taps and showers for at least 2 minutes weekly while the property is empty

For properties with stored water (cold tanks or hot water cylinders)

6Ensure the cold water tank is properly covered, insulated, and free of debris
7Check the tank annually for signs of corrosion, scale, or contamination
8Confirm the hot water cylinder thermostat is set to 60°C — not turned down to save energy

For HMOs and larger properties

9Consider a written water management scheme — the HSE expects a more formalised approach for properties with complex systems
10Keep a temperature monitoring log — spot-check outlet temperatures quarterly and record the results
11Arrange annual inspections of tanks, cylinders, and TMVs

Void periods are the biggest risk

The most common scenario where Legionella becomes a real problem in rental properties is the void period. When a property is empty:

Water sits in pipes at ambient temperature — right in the danger zone
No one is running taps, so there is no flushing
Biofilm builds up inside pipework, providing nutrients for bacteria

Before a new tenant moves in, you should always:

1Run every tap (hot and cold) for at least 2 minutes
2Run every shower for at least 2 minutes
3Flush every toilet
4Run any rarely used outlets (utility room taps, outside taps)

If the property has been empty for more than a month, consider running the hot water system up to 60°C+ and flushing through all outlets at temperature. This is called a thermal flush and kills Legionella bacteria in the system.

Document that you did this. A note in your property management system with the date and what you flushed is sufficient.

Cost of a Legionella risk assessment

Property type	Typical cost
1-bed flat	£50–£80
2–3 bed house	£70–£120
4–5 bed house	£100–£150
HMO (6+ rooms)	£150–£300
Large HMO with stored water	£200–£400

These are one-off assessment costs. Remedial work — replacing a showerhead, lagging pipes, fitting a tank lid — is usually under £100 for a standard property.

For comparison: the cost of a Legionella prosecution is unlimited. Even a civil claim from a tenant who contracted Legionnaires' disease would dwarf the cost of an assessment many times over.

Penalties for non-compliance

Unlike gas safety (which has a clear £6,000 civil penalty), Legionella enforcement operates under general health and safety law:

HSE prosecution under the Health and Safety at Work Act: unlimited fine and up to 2 years' imprisonment
Local authority prosecution under COSHH: unlimited fine
Civil claims from tenants: damages for personal injury, including loss of earnings, medical costs, and general damages for pain and suffering
Coroner's inquiry: if a tenant dies from Legionnaires' disease, the coroner will investigate and the landlord's compliance record will be examined

The HSE has stated publicly that having no risk assessment at all is indefensible. Even if your property is low risk, you need the assessment to prove it.

Tenant communication

You are not legally required to give tenants a copy of the Legionella risk assessment (unlike gas safety certificates, which must be provided). However, you should:

Include a clause in the tenancy agreement asking tenants to run taps and showers regularly if they go away for more than a week
Ask tenants not to adjust the hot water thermostat below 60°C
Instruct tenants to clean showerheads — or schedule it as part of periodic inspections
Inform tenants if any outlets are rarely used and ask them to flush these weekly

This is both good practice and evidence that you have taken reasonable steps to manage the risk.

How to track Legionella compliance across a portfolio

If you manage more than a handful of properties, tracking Legionella assessments manually becomes a liability. You need to know:

When each property was last assessed
When each assessment is due for review
Whether remedial actions have been completed
Whether void period flushing was documented

Spreadsheets work until they don't — a missed cell, a forgotten tab, and suddenly you have a property with no assessment and a new tenant moving in.

Proplio tracks Legionella assessment dates alongside gas safety, EICR, EPC, and every other compliance certificate in one place. You set the date, and Proplio reminds you before it's due. No spreadsheet, no guesswork.

Related guides on Proplio:

This article is for general guidance and applies to England and Wales. Legionella risk management in Scotland and Northern Ireland follows the same HSE framework but may have additional local authority requirements. Always refer to the current HSE Approved Code of Practice L8 and seek professional advice for complex water systems.