Legionella risk assessments for landlords

What legionella is and why it matters

Legionnaires' disease is a potentially fatal form of pneumonia caused by breathing in tiny droplets of water contaminated with legionella bacteria. Man made hot and cold water systems can provide conditions for growth, including the pipes, tanks and showers found in rented homes.

The bacteria multiply particularly between 20 and 45 degrees Celsius. Stagnation, scale, rust and sludge can encourage growth, while showers and spray outlets can release droplets that people inhale. An apparently clean bathroom does not establish that the hidden water system is well controlled.

Older people, smokers and people with certain illnesses or weakened immune systems are more susceptible. An ordinary, regularly used domestic system may present a low risk, but the assessment should consider who could be exposed rather than assuming every home needs identical precautions.

What the law asks of landlords

HSE's landlord guidance covers property rented under a lease or licence shorter than seven years, including a room in an owner's home. It explains landlords' responsibilities under the Health and Safety at Work etc Act 1974 and the Control of Substances Hazardous to Health Regulations 2002, known as COSHH.

The practical task is to identify and assess the risk, introduce proportionate controls and check that those controls work. HSE's Approved Code of Practice L8 explains the framework, while HSG274 Part 2 gives technical guidance for hot and cold water systems. A low risk finding should have a clear basis.

L8 has special legal status: following its advice is not compulsory, but an alternative approach needs to demonstrate compliance. Do not treat guidance as a requirement to buy an annual certificate or apply a commercial monitoring schedule to every small flat. Take professional advice where duties or control arrangements are unclear.

Is there a legionella certificate

There is no statutory legionella certificate equivalent to a gas safety record. HSE does not require landlords to obtain a legionella test certificate. A suitable assessment and effective precautions matter more than a document marketed as proof that a property is safe.

A landlord can assess a straightforward domestic system if they have enough knowledge to understand its layout, identify hazards and decide suitable controls. HSE does not require professional accreditation for this task. Downloading a checklist is useful only if the person completing it understands the answers.

Commission a competent assessor if you cannot identify the storage arrangements, explain temperature controls or judge the significance of little used pipework. Ask about experience with comparable properties, what the visit includes and whether the report will identify actions, priorities and responsibilities rather than simply provide a pass or fail.

What a risk assessment covers

Start with the whole system, from the incoming supply to every relevant outlet. Establish whether cold water is mains fed or stored and whether hot water comes from a combi boiler, cylinder or shared plant. Record areas that could not be inspected and arrange follow up rather than assuming they are satisfactory.

The assessment should describe potential sources of exposure, existing precautions and the people responsible. For a straightforward home, a clear description may suffice; larger systems need a usable schematic showing storage, circulation and outlets so that monitoring points and stagnant branches can be identified.

Turn observations into an action plan. A missing tank lid, an unknown cylinder setting and a redundant shower branch need specific decisions, not just photographs. Allocate each action to someone, set an appropriate completion date and record how completion will be checked.

• Check cold water tanks for suitable covers, cleanliness, insulation and turnover.
• Identify cylinders, heaters, circulation loops and actual operating temperatures.
• Locate showers, spray taps, unused outlets and redundant pipework.
• Consider occupancy, prolonged absences and people especially susceptible to infection.
• Review cleaning, maintenance, previous faults and arrangements for access.

Simple controls for most rented homes

Keep hot water hot, cold water cold and water moving. Where temperature is the control method, HSE guidance uses hot water storage at least at 60 degrees Celsius and distribution reaching at least 50 degrees Celsius within one minute at outlets. Cold water should be below 20 degrees Celsius after running for two minutes.

These checks concern the water system, not just a thermostat dial. A cylinder setting does not prove the correct temperature reaches distant taps. An assessor should choose suitable measurement points, explain how to check them safely and specify a proportionate monitoring schedule. Investigate repeated failures rather than merely recording them.

Scalding also needs control, especially for vulnerable occupants. Thermostatic mixing valves can limit temperatures at selected outlets while hotter water is maintained upstream. Mixed tap temperatures cannot simply be compared with the hot distribution target. Have a competent person check the arrangement and maintain valves to the manufacturer's instructions.

Keep tanks covered and insulation sound, and address heat transfer that warms cold pipes. Inspect tanks and clean where necessary rather than assuming annual cleaning is always required. HSG274 recommends cleaning and descaling shower heads and hoses quarterly, or at a frequency indicated by fouling and other risks. Record the property's agreed approach. For stored systems, HSE describes six monthly checks at the cold tank inlet and at least annual visual tank inspections. The assessor should decide how these checks apply to the installation and identify who can safely reach the tank. Do not ask tenants to enter a loft or interfere with equipment to complete a routine log.

Empty properties and unused outlets

An empty property needs an active water management plan. A spare bathroom or an unoccupied HMO room can also stagnate while the rest of the building remains occupied. List every little used outlet, including outside taps and utility sinks, so the flushing routine does not stop at the kitchen and main bathroom.

HSG274 recommends flushing infrequently used outlets weekly, or as indicated by the assessment. Run them until the outlet temperature stabilises and is comparable with the supply, purging water to drain. A fixed instruction to run every tap for thirty seconds may not replace stagnant water in longer pipe runs.

Reduce aerosol release and avoid exposing the person doing the work to spray. The assessor should explain a safe method, particularly for showers. Record the outlet, date, person and any problem, and arrange cover if the usual contractor cannot attend. A missed visit should trigger follow up.

Before reletting, confirm that flushing and any cleaning or remedial work are complete. Do not casually drain down a complex system: obtain advice on shutdown and recommissioning. Where an outlet is permanently redundant, ask a competent plumber to remove associated dead legs rather than leaving capped lengths of stagnant pipe.

Does water need to be tested

Routine legionella sampling is not usually needed in domestic hot and cold water systems. Temperature monitoring and checking that other precautions work are different from laboratory testing. A sales recommendation for an annual sample does not itself establish a need at every rental property.

Sampling may be appropriate when there is doubt about control effectiveness, temperatures cannot be maintained or other system risks justify investigation. A competent specialist should decide where and when to sample and how to interpret results. One negative sample is not proof that every part of a system is safe.

Where sampling is justified, HSE refers to BS 7592 and analysis by a UKAS accredited laboratory. Agree the response to results before commissioning tests. If legionella is detected, obtain prompt specialist advice on exposure controls, investigation and remedial work rather than relying on repeated samples without fixing the underlying problem.

HMOs, letting agents and higher risk features

An HMO is not automatically a high risk water system, but multiple bathrooms, intermittent occupancy and larger storage volumes can make control harder. Assess the actual installation and use. A shared cylinder serving several floors presents different issues from separate flats with individual combi boilers and no stored water.

Larger systems may need defined sentinel outlets, checks of circulating hot water returns and a planned rotation of representative outlets. Long pipe runs, oversized tanks and poorly balanced circulation can defeat temperature control. Use an assessor experienced in the relevant system rather than transferring a small house checklist without adaptation.

Landlords and agents should agree in writing who commissions assessments, arranges access, checks records and authorises repairs. Using an agent or contractor does not remove the need to ensure precautions happen. Where a freeholder controls communal plant, obtain relevant information and clarify responsibility for the supply and the installation inside each flat.

Give contractors a clear escalation route for missed flushing, inaccessible rooms and failed temperature checks. If specialist equipment such as a spa pool is present, seek system specific advice. It should not be treated as just another bathroom outlet covered by an ordinary domestic assessment.

Practical guidance for tenants

Provide short, property specific instructions at handover. Explain which taps or showers need regular use, how to flush safely after an absence and how shower heads should be cleaned and descaled. Show tenants the reporting route rather than simply attaching a technical report they may not understand.

Ask tenants not to alter cylinder or boiler temperature settings without agreement. Encourage reports of hot water becoming unexpectedly lukewarm, cold water remaining warm, poor flow, faulty showers or outlets that are no longer used. Explain that these observations help identify faults; they do not diagnose legionella contamination.

Agree realistic arrangements for holidays and cleaning, particularly in shared houses where residents may assume someone else handles communal showers. If a tenant cannot safely carry out a task, arrange suitable assistance. Tenant instructions support the landlord's precautions but are not a substitute for maintenance, assessment or access arrangements.

Records and review

Keep the assessment, system description, responsible person's details and action plan together. Add flushing logs, relevant temperature readings, inspection findings, cleaning records and repair evidence. Record what happened when a reading failed, not just the number. A dated note confirming who checked a completed repair makes the record more useful. Store records where a replacement agent or contractor can find them, with the latest version clearly identified.

HSE says landlords with fewer than five employees do not have to record assessment findings, although keeping a record is sensible. Where L8 record keeping requirements apply, retain assessments while current and for at least two years afterwards, and monitoring, inspection and check records for at least five years.

Review regularly and whenever the assessment may no longer be valid. Triggers include altered pipework, changed storage or heating equipment, prolonged vacancy, changed use or susceptible occupants, failed controls and suspected linked illness. HSE does not prescribe an annual or two yearly replacement assessment for every rented home; choose review arrangements that reflect the risks.

At tenancy changes, check that the description, controls and contact details still match the property. An unchanged, effective low risk assessment need not be rewritten simply to renew a certificate. This guide is general information, checked October 2026. Ask a competent assessor about technical uncertainties and a solicitor about disputed legal responsibilities.