Legionella Risk Assessment: Landlord Obligations

If you rent out a place with running water, you are expected to assess and control legionella risk, but for a normal BTL you do not need a fancy certificate or lab tests -- a simple, competent risk assessment is enough.

"This guide provides general information about UK landlord tax obligations. It is not financial or legal advice. Tax treatment depends on your individual circumstances and may change. Consider consulting a qualified accountant or solicitor for advice specific to your situation."

1. Legal basis and what "risk assessment" actually means

Law and guidance

• Duties come from the Health and Safety at Work etc. Act 1974 and the Control of Substances Hazardous to Health Regulations (COSHH).
• HSE's Approved Code of Practice L8 and leaflet INDG458 explain what you must do in practice.

For domestic rentals, HSE's view is

• You must assess the risk of exposure to legionella and control it.
• In most normal houses and flats, the risk is low because water is used regularly and systems are simple.
• You do not need an "in-depth, detailed assessment" or automatic annual lab testing.

A legionella risk assessment for a standard let should

• Identify the water system layout (mains direct, cold storage tank, hot water cylinder, combi boiler).
• Check for conditions that could promote growth:
• Water temperatures in the 20-45C range.
• Stagnation (little-used outlets, dead legs).
• Scale, sediment and biofilm in tanks or pipework.
• Identify who could be at risk (older or vulnerable tenants).

2. Who can do it, how often, and what you do in voids

Competent person

• ACoP L8 says the dutyholder must appoint a "competent person" (responsible person) to manage legionella risk.
• For a simple domestic system, that can be you as landlord if you have "sufficient authority, competence and knowledge of the installation" and have read the HSE guidance.
• You do not have to use an external assessor, and HSE explicitly says there is no requirement for a 'Legionella certificate'.

Frequency

• There is no fixed legal interval in L8 or INDG458.
• Good practice:
• Do an assessment at the start of a new tenancy or when you first let.
• Review if anything changes: new boiler, cylinder, major plumbing, long void, change to more vulnerable occupiers.

Void periods

If a property is empty, water can stagnate. HSE-aligned practice is:

• Flush all outlets (hot and cold taps, showers) at least weekly, or at minimum before a new tenant moves in.
• Run hot water until it comes through at 50C+, and ensure stored hot water is kept at 60C at the cylinder.
• Flush any little-used outlets (eg en-suite showers) regularly even in tenanted periods.
• You should record that you have done this (quick log entry) so you can prove you took reasonable steps.

3. What to record, HMOs vs single lets, and typical costs

Record keeping

INDG458 and ACOP L8 say you should document the risk assessment, control scheme and checks.

For a standard house or flat, a simple one-page record is fine:

• Property address, date, assessor (you).
• System type (combi / cylinder / cold tank).
• Identified risks (eg old cold water tank, seldom-used shower).
• Control measures (temperature settings, regular use/flush, tank inspection).
• Review date and any actions taken.

HMOs

• HMOs have more complex water systems and more showers, so risk is higher.
• You must do a legionella risk assessment as part of your overall risk assessments (fire, general safety) under the HMO Management Regulations.
• For HMOs with stored water, longer pipe runs, or vulnerable tenants, using a specialist water hygiene consultant is often worth it.

Costs if you use a professional

• Single domestic property: typically GBP 90-200 if you pay directly.
• Through a letting agent managing many units: often GBP 50-100 per property.
• There is no legal need to buy these reports if you can do a competent assessment yourself.

4. If legionella is found, and what landlords get wrong

If legionella is detected or risk is high

For standard domestic properties, routine water sampling is not normally required; it is more relevant to complex systems like cooling towers or large communal systems.

If you do find Legionella or have a high-risk system, ACOP L8 / HSG274 say you should:

• Take immediate control measures: raise temperatures, flush, clean/disinfect tanks, remove dead legs.
• If necessary, shock chlorinate the system using a contractor.
• Review and improve your written control scheme.
• Inform and advise tenants, especially vulnerable ones.

Common misunderstandings

"I need an expensive annual certificate." HSE is very clear: there is no legal requirement for a commercial "Legionella certificate" in normal domestic lets; simple risk assessment and basic controls are enough.

"Someone has to take water samples every year." Routine sampling is not required in typical rented houses/flats; it is aimed at high-risk systems like cooling towers, large hot water systems in hospitals, etc.

"Because the risk is low, I can ignore it." HSE does not proactively inspect homes, but if there is a case of Legionnaires' disease linked to your property, you must show you assessed and controlled the risk, or you risk prosecution under HSWA/COSHH.

"Only agents are responsible; I can delegate it." You can ask an agent or consultant to act as your competent person, but the legal duty as dutyholder remains with you as landlord.

Practical, low-effort control for a normal BTL

• Prefer mains-fed combi boilers or unvented cylinders; avoid old, open cold water tanks if you can.
• Set hot water so the cylinder stores at 60C and outlets reach 50C+ quickly.
• Remove unused pipework and outlets where possible; flush little-used outlets regularly.
• At each new tenancy:
• Flush all taps and showers.
• Note system type and any obvious risks.
• Record the date and confirm to the tenant that the system has been checked and how to use it safely.

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