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💧 Stored Water · Void Rooms · Licensing

Legionella Risk Assessment for HMOs & Shared Houses

HMOs sit exactly where domestic Legionella risk stops being trivial. A single family home with a combi boiler and daily use is genuinely low risk — the HSE says so. A three-storey shared house with a loft tank, six en-suites, a room empty between tenancies and a shower nobody used all summer is a different system entirely. We assess the second and we will tell you honestly if you are the first.

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We Tell You If You Don't Need Us

If your property is a simple domestic system with daily use, we will say so. There is no legal requirement to hold a Legionella “test certificate”.

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Built for Void Periods

The gap between tenancies is when risk actually rises. The control scheme covers it, with log sheets.

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Something to Give the Council

A dated written assessment and a control scheme — what licensing officers ask for when they ask at all.

Why HMOs Sit in the Middle

Not Every Let Needs This. Some Genuinely Do.

This is a part of the compliance market with a poor reputation, and it is worth being blunt about why. Companies have sold domestic landlords annual assessments and “certificates” they do not need, and the HSE has publicly said as much. The duty is real; the way it is often sold is not. What decides the answer is the water system, not the label on the property.

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    The duty exists, and it is not the same as needing a consultant. As a landlord you have a duty under the Health and Safety at Work etc. Act 1974 to ensure the risk from Legionella is assessed and controlled. For a simple, low-risk domestic system the HSE accepts that you may be able to carry out that assessment yourself. What you must not do is ignore it.
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    There is no such thing as a required Legionella certificate. If a company is offering you a certificate as a legal requirement for a domestic let, that is a sales device, not a legal duty. We do not sell one.
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    Stored cold water changes the picture. A loft tank — common in older converted HMOs — holds water that warms in summer, may be uncovered or full of debris, and turns over slowly. That is the clearest single reason a shared house moves out of the low-risk category.
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    Void rooms and long voids are the real HMO risk. Student properties standing empty from June to September, or an en-suite in a room let sporadically, produce exactly the stagnation Legionella needs. The first shower after a long void is the moment of highest risk in the whole year.
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    More outlets means more dead legs. Every en-suite added during a conversion adds pipework, and every reconfiguration leaves blanked-off runs behind. Converted HMOs accumulate these, and they are invisible without tracing the system.
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    Licensing teams increasingly ask. Some councils request evidence of Legionella assessment as part of HMO licensing or during inspection. It is not universal, and it varies by authority — but if yours asks, a dated assessment and a control scheme is what satisfies it.

What we work through with you

Whether your system is genuinely low risk — asked first, honestly · Cold water storage, if any: temperature, lid, condition, turnover · Hot water generation and outlet temperatures · Dead legs left by conversion work · En-suites and little-used outlets · Void-period flushing regime · Shower heads and hoses · Outside taps and garden supplies · What tenants need to be told and how · A written control scheme and log sheets you or your agent can run.

On Site

What We Assess in an HMO

The visit follows the water from where it enters the building to every outlet it can reach.

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Cold Water Storage

Loft and airing-cupboard tanks: temperature, lid and screen, debris, insulation and how quickly the water turns over.

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Hot Water & Outlet Temperatures

Cylinder or combi, distribution temperatures, and how far the furthest outlets drift from the target.

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Dead Legs From Conversion

Blanked-off pipework left behind when bathrooms were added or moved. Traced and mapped, because you cannot flush what you do not know about.

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En-Suites & Little-Used Outlets

The rooms let intermittently, the second bathroom, the outside tap — every outlet a flushing regime has to cover.

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Showers & Aerosol Points

Head and hose condition, scale, and descaling intervals. Showers are the main route by which the bacteria reach a person.

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Void Regime & Records

What happens between tenancies, who does it, and whether there is a log to show it happened.

In Practice

What We Most Often Find

Recurring across student houses, professional shares and converted bedsit HMOs.

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An Uncovered or Debris-Filled Loft Tank

Still supplying the property, warm in summer, and not checked since installation.

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A Summer-Long Void With No Flushing

Standard in student lets. The September move-in shower is the highest-risk moment of the year, and it is entirely preventable.

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Dead Legs From an Old Bathroom

Pipework capped off during a conversion, still connected, still holding water at room temperature.

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An Assessment and Nothing Else

A report bought years ago, no control scheme, no logs. The assessment on its own does not discharge the duty.

The Stakes

The duty is real even where the risk is low

A landlord's duty to assess and control Legionella risk arises under the Health and Safety at Work etc. Act 1974, and where the property is managed as part of a business, COSHH and ACOP L8 come into play as well. The HSE's position is that many simple domestic systems are low risk and can be assessed simply — but low risk is a conclusion you reach by assessing, not an assumption you make instead. Where a property has stored water, long voids or a converted system, the risk is genuinely higher and so is the expectation on you.

Tell Us About the Premises. Fixed Fee in 2 Hours.

Property type, rough size, number of storeys and what it is used for is enough for us to quote. Survey within days, and your written report within 48 hours of the visit.

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Frequently Asked Questions

Do I legally need a Legionella risk assessment for my HMO?
You have a legal duty to ensure the risk is assessed and controlled — that comes from the Health and Safety at Work etc. Act 1974, and from COSHH and ACOP L8 where the property is part of a business operation. What that duty requires in practice depends on the system. For a simple, low-risk domestic system the HSE accepts that a landlord may carry out a simple assessment themselves. An HMO with a stored cold water tank, multiple en-suites or long void periods is not that simple system, and a proper assessment is the sensible course.
Is there such a thing as a Legionella certificate?
No, not as a legal requirement. There is no certificate a domestic landlord is obliged to hold, and the HSE has publicly cautioned about companies selling them. What the law asks for is that the risk is assessed and then controlled — an assessment document plus a control scheme that is actually being followed. We do not offer a certificate, because there is nothing to certify.
Will my council ask for one as part of HMO licensing?
Some do and some do not, and the requirement varies between authorities and between licensing schemes. Where it is asked for, a dated written assessment and a control scheme is what satisfies it. Because the position varies locally, it is worth checking your own council's licensing conditions — our free HMO licensing lookup covers the councils across our service area.
What is the biggest risk in a student HMO?
The summer void. A property standing empty from June to September leaves water sitting in the pipes at room temperature for months, and the first shower taken in September produces an aerosol from water that has been stagnating the whole time. Flushing every outlet before re-occupation, and periodically during the void, is the single most valuable control in student housing — and it is cheap, because it costs time rather than money.
Do I need to test the water?
Usually not. The primary controls are temperature and turnover, not sampling. Testing has a role where the control scheme is not achieving its target temperatures, where there is an unusual system, or after a suspected case. A provider whose first offer is water sampling rather than an assessment of your system is selling the wrong thing first.
Can I do the assessment myself?
For a simple domestic system with no stored water and regular use, the HSE's guidance indicates that you may be able to. Where the property has a cold water storage tank, a complex or converted layout, multiple little-used outlets or extended voids, it becomes considerably harder to do competently — and the point of the assessment is to identify things you would not otherwise know were there, such as dead legs behind a wall. Tell us about your system and we will give you a straight view on which side of that line you are.
What do you actually hand over?
A written assessment describing the system as we found it, a schematic, the identified risks with recommendations, and a control scheme: which outlets to flush and how often, which temperatures to check and where, tank inspection intervals and shower descaling schedules — laid out as a calendar with log sheets, so you or your letting agent can run it in minutes a month.
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