HMO Legionella Risk Assessments in London
Understand the hot and cold water system, identify conditions that can allow Legionella bacteria to grow, and record proportionate controls for the way your shared property is occupied. Send the HMO layout, stored-water details, vacancy pattern and access notes for a suitable assessment quotation.
Who must manage Legionella risk in an HMO?
The legal duty sits with the landlord or person who controls the rented premises and its water system. The Health and Safety Executive explains that the Health and Safety at Work etc. Act and COSHH provide the framework for assessing and controlling exposure to Legionella. Using a managing agent or contractor can allocate practical tasks, but the parties should record clearly who is responsible for decisions, routine controls, repairs and review.
HMO management duties also require the manager to keep the water supply and drainage system in good, clean and working condition. That includes accessible tanks or cisterns used for domestic water. A Legionella assessment supports this wider management work; it does not replace HMO licensing, plumbing maintenance or the licence conditions issued by the relevant London borough.
A proportionate assessment may conclude that a simple, well-used domestic system is low risk. That is a valid outcome when it is based on the real installation and sensible controls. The aim is not to manufacture defects or sell unnecessary sampling, but to show how the dutyholder reached the conclusion and how the risk will remain controlled.
- Who owns and manages the property?
- Who controls the hot and cold water system?
- Who carries out routine flushing and checks?
- Who will authorise repairs and close actions?
Which HMO water-system features need closer attention?
Regular use and good water turnover usually keep domestic risk low. HMOs can nevertheless develop less predictable patterns as residents change, rooms become vacant and bathrooms are shared. The assessor should trace the features that affect bacterial growth and exposure rather than relying on a generic room count.
Stored hot or cold water
Tanks, cylinders and calorifiers need to be understood, including their condition, lids, temperatures, capacity and whether water is turned over as intended.
Little-used outlets
Empty letting rooms, spare bathrooms, outside taps and disused fixtures can allow water to stagnate. Identify who flushes them and how that work is recorded.
Showers and aerosols
Shared showers create fine water droplets that can be inhaled. Usage, cleanliness, scale, flexible hoses and the routine for cleaning showerheads all matter.
Temperature control
Water that is neither reliably hot nor cold can support bacterial growth. The assessment should consider generation, storage, distribution and safe temperature monitoring.
Dead legs and alterations
Redundant pipework, capped branches and poorly planned extensions can retain stagnant water. Recent conversion work may have changed the system without updating records.
Occupancy and vulnerability
Resident turnover, long absences and people who may be more susceptible to illness affect how controls, communication and prompt fault reporting should be managed.
A low-risk finding still needs context. Record why regular use, direct mains cold water, instantaneous or low-volume hot-water provision and simple pipework keep the risk low. Then identify the changes that would require the conclusion to be reviewed.
What should an HMO Legionella assessment cover?
The appointment scope should reflect the property. A useful assessment combines available records, a visual inspection of accessible components, discussion with the person managing the building and proportionate checks. It should make limitations obvious rather than presenting assumptions as confirmed facts.
Do you need sampling or a Legionella certificate?
HSE guidance says microbiological sampling for Legionella is not usually required for domestic hot and cold water systems. Sampling is reserved for specific circumstances and should have a clear purpose. It must not be added automatically to make a simple assessment appear more thorough.
Temperature monitoring is different. It can help show whether the water system and its control measures are working as intended, but a single set of readings is only a snapshot. Results must be interpreted alongside the system layout, how the HMO is used and the controls that will continue after the visit.
Health and safety law does not require a standard landlord Legionella test certificate. A written risk assessment report is valuable because it can show what was inspected, what was found and what needs to happen next. It cannot certify that no Legionella bacteria exist or remove the dutyholder's ongoing responsibility.
If a council, buyer, insurer or managing agent asks for a “certificate”, forward the exact wording. They may actually need a current risk assessment, an action-closure record, temperature evidence, a maintenance document or a laboratory result following a specific concern.
Practical controls for a domestic-type HMO system
The assessment decides which controls are appropriate. HSE highlights temperature and water movement as reliable foundations for most domestic systems. The controls below are examples, not a substitute for understanding the installation or managing scalding and other water-safety risks.
Manage temperatures
Keep cold water cold and hot water appropriately hot. HSE gives storing water in a calorifier at 60°C as an example control; distribution and outlet safety need competent consideration.
Maintain water movement
Flush the system before letting after stagnation and include little-used outlets in a suitable routine. Avoid creating spray and scalding exposure while flushing.
Keep components clean
Clean and disinfect showerheads as required, control scale and debris, and ensure accessible cold-water tanks have secure, close-fitting lids.
Remove redundant pipework
Ask a competent plumbing professional to address dead legs, unused branches and defects that prevent the system from operating as intended.
Give residents clear instructions
Explain how to report poor hot-water performance, discoloured water, faulty showers or unused outlets, and tell residents not to alter agreed control settings.
Close actions visibly
Keep invoices, photographs, temperature records and contractor notes with the assessment so the property file shows that recommendations were completed.
Plan for empty rooms, student changeovers and renovation
HMOs can be partly occupied while individual rooms remain empty, so overall building occupancy does not prove that every outlet receives regular use. Create an outlet list for empty rooms, ensuite facilities, spare bathrooms, external taps and any isolated kitchenette. Allocate the flushing work to a named person and keep a simple dated record.
HSE advises that hot and cold outlets should generally be used at least once a week to maintain water flow. A suitable flushing regime or other measure may be needed during a longer closure. If the whole system is drained, disinfected or recommissioned, use competent advice appropriate to the system rather than improvising a generic procedure.
Before reoccupation, check that agreed controls have resumed, faults are resolved and residents know how to report water problems. A report written before a long vacancy may need review because the operating conditions on which it relied have changed.
- List every outlet affected by low use
- Name the person responsible for the regime
- Record dates, exceptions and access problems
- Review controls before residents return
There is no automatic annual or two-year expiry date
HSE does not prescribe an annual or biennial review cycle for domestic rented property. The dutyholder should review the assessment periodically and whenever there is reason to think it may no longer be valid. A diary reminder can still be useful, but it should not replace change-led review.
System alterations
Review after replacing a cylinder, adding bathrooms, altering pipework, changing a tank, fitting new showers or completing a significant conversion.
Occupancy changes
Long vacancy, seasonal use, a different letting pattern or a resident who may be more vulnerable can change the assumptions in the original assessment.
Control failures
Repeated temperature shortfalls, missed flushing, scale, poor water turnover or unresolved maintenance indicate that the current control scheme needs attention.
New information
A relevant complaint, laboratory result, suspected illness, contractor observation or council request should be evaluated rather than filed without review.
What to send for a relevant quotation
Start with the full address and postcode, then describe the property rather than sending only the words “HMO certificate”. State the number of storeys, letting rooms, residents, showers and communal bathrooms. Explain whether hot water comes from a combi boiler, cylinder, calorifier or another arrangement, and whether cold water is stored.
Identify empty rooms, little-used outlets, tanks, plant areas and anything that cannot be accessed safely. Send the previous risk assessment, any water-system diagram, maintenance records, temperature concerns, refurbishment details and the exact request from the council, lender, buyer, insurer or managing agent.
The quotation should confirm whether the work is an assessment and report only or also includes agreed monitoring. Sampling, tank cleaning, disinfection, plumbing repairs, access equipment and action verification are separate unless expressly included.
- London postcode and HMO layout
- Occupancy, vacancies and deadline
- Hot-water and stored-water details
- Showers, little-used outlets and access
- Previous reports, faults and alterations
- Exact third-party request or licence wording
Other HMO records that may be managed alongside water safety
A Legionella risk assessment does not inspect gas appliances, electrical installations, carbon monoxide alarms or fire precautions. Use the relevant assessment or certificate route for each part of the property file.
Check the current HSE and HMO management guidance
This guide explains the enquiry and decision process for London HMOs; it is not legal or medical advice. Use the official sources for the underlying duties, technical guidance and current wording.
HMO Legionella risk assessment FAQs
Does every HMO need a Legionella risk assessment?
The landlord or person in control of rented premises must assess and control the risk of exposure to Legionella. That duty applies to HMOs, but the assessment should be proportionate. A straightforward domestic-type system with regular water use may be low risk, while stored water, long pipe runs, several showers, vacant rooms or little-used outlets can justify closer attention.
Is an HMO Legionella certificate a legal requirement?
Health and safety law does not require landlords to obtain a standard Legionella test certificate. The requirement is to assess the risk and control it. A written assessment report is useful evidence because it records the system, findings, actions, responsibilities and review triggers, but it should not be described as a council-issued certificate or a guarantee that bacteria are absent.
How often must an HMO Legionella assessment be renewed?
HSE guidance does not set an annual or two-year renewal date for domestic rented property. Review the assessment periodically and when circumstances change, including alterations to the water system, refurbishment, long vacancy, different occupancy, new control measures, recurring temperature problems or evidence that the existing controls may no longer be effective.
Does a Legionella risk assessment include water sampling?
Not as a routine part of a domestic assessment. HSE guidance says Legionella sampling is not usually required for domestic hot and cold water systems and is needed only in specific circumstances. Temperature checks are different from laboratory sampling. Tell the assessor about any previous result, suspected case, persistent control failure or sampling request before the scope is agreed.
Can an HMO landlord complete the assessment personally?
A landlord who understands the water system, can identify the relevant risks and can put suitable controls in place may assess a simple domestic arrangement. Use competent external help if the system is unfamiliar or complex, responsibilities are divided, records are poor, risk controls have failed or you are not confident that you can make and document a suitable assessment.
What should an HMO Legionella assessment report contain?
A useful report should identify the dutyholder and property, describe accessible parts of the hot and cold water system, record relevant risk factors and limitations, state the controls already in place, list proportionate actions with priorities, identify who will manage them and explain when the assessment needs review. It should distinguish assessment work from sampling and remedial plumbing.
What should happen when an HMO is empty or partly vacant?
Water should not be allowed to stagnate. HSE guidance advises managing extended vacancy with a suitable flushing regime or, for a long closure, considering other measures such as draining the system. Little-used hot and cold outlets should generally be used at least weekly to maintain flow. The safe method must reflect the system and avoid exposing anyone to aerosols or scalding.
What details are needed for an HMO Legionella assessment quotation?
Send the full London address and postcode, number of storeys and letting rooms, occupancy and vacancy pattern, how hot water is produced, whether cold or hot water is stored, the number of showers, known little-used outlets, tank or plant access, previous reports or complaints, the reason for the assessment and the date the report is required.
Request an HMO Legionella risk assessment in London
Include the postcode, HMO layout, occupancy and vacancy pattern, hot-water arrangement, stored-water and shower details, access contact, existing reports and deadline. We will confirm the suitable enquiry route.