Water hygiene · UK pillar guide
Legionella Risk Assessment: the definitive UK guide
Water-system risk assessment for rented homes — done honestly. Everything a landlord needs on one page — the law by nation, the process, pricing guidance, and every area we cover.
Straight answer
Legionella risk assessment report
Landlords everywhere in the UK must assess and control legionella risk in their properties' water systems — but there is no statutory 'legionella certificate' and no fixed annual renewal. What the law expects, per HSE guidance, is a suitable risk assessment kept up to date; for a simple domestic property in any UK area that's a straightforward review of tanks, pipework and outlets.
Landlords must assess and control the risk of exposure to legionella in their properties. For most ordinary domestic lets the assessment is simple, and the law does not require a certificate, an annual renewal, or testing of the water.
Water hygiene
What does the law actually require?
That landlords assess and control the risk of legionella bacteria in their property's water systems — a duty arising under the Health and Safety at Work etc. Act framework and applying to residential lettings UK-wide. HSE guidance (the ACOP L8 framework and HSG274) defines what suitable assessment and control look like; for a simple domestic property the answer is genuinely simple.
What the law does not require is the thing most commonly sold: there is no statutory legionella certificate, no prescribed annual renewal, and no rule that the assessment must be bought from a specialist. A competent landlord can assess a straightforward domestic system themselves; many choose professional documentation for assurance — a preference, not a mandate.
Water hygiene
Why is there no annual certificate?
Because the duty is risk-based and most domestic rentals are low risk: mains-fed cold water, combi boilers with no stored hot water, short pipe runs and regular use leave little for legionella to exploit. The HSE has publicly warned about companies implying that landlords need mandatory annual legionella certification — the warning exists precisely because the mis-selling is common.
The lawful rhythm is review-on-change: reassess when the water system changes, when the pattern of use changes, or when evidence suggests controls aren't working. A five-year-old assessment of an unchanged low-risk flat can be perfectly current; last year's assessment is stale the day the hot water system is replaced.
Water hygiene
What does a suitable assessment cover?
A trace of the system from where water enters: any stored cold water and its tank condition, the cylinder or combi arrangement, pipe runs including dead legs and redundant sections, and the outlets — with showers noted particularly as spray-formers. Temperatures are checked against the classic thresholds (hot storage at 60°C or above, cold staying cold), stagnation points identified, and existing controls recorded.
The written output should read like a description of your actual property, not a template: system type, risk points found, controls in place or recommended, tenant advice issued, assessor and date. Proportionality is the quality marker — a combi flat written up as low-risk with simple controls is a good report, not a lazy one.
Water hygiene
Which properties are genuinely higher risk?
The risk factors are specific: water stored between roughly 20°C and 45°C, open or poorly covered cold-water tanks, long or complex pipework with dead legs, outlets that go unused for weeks, and spray-forming fittings. Properties that accumulate several — older houses with tank-fed systems, HMOs with shared showers and sporadically occupied rooms, holiday lets with long voids — justify professional assessment and a firmer review rhythm.
Void periods deserve their own mention because they manufacture risk in otherwise fine properties: water standing in an unused system is the textbook condition. Flushing every outlet thoroughly before a new tenancy, and noting it, is the single highest-value habit in domestic water hygiene.
Water hygiene
What controls matter day to day?
Hot water stored hot (60°C or above at the cylinder), cold kept cold, showerheads cleaned and descaled, redundant pipework insulated or ideally removed, and outlets flushed after any period of disuse. Tenant advice completes the set: run little-used taps and showers before normal use after absences, keep showerheads clean, report water system problems promptly — a short written note that is itself an evidenced control.
Laboratory sampling sits deliberately last: it's a tool for complex or higher-risk systems and for investigating suspected control failures, not a default line item for ordinary rentals. If a quote for a one-bed combi flat includes routine sampling and an annual renewal plan, the report is serving the seller.
FAQ
Every common question, answered
What is a legionella risk assessment?
A review of a property's water system — tanks, cylinders, pipework, outlets — to identify where legionella bacteria could grow and what controls are needed. For most simple domestic rentals the assessment is straightforward.
Is a legionella risk assessment legally required for rentals in your area?
Landlords across the UK have a duty under health and safety law to assess and control legionella risk. There is no statutory certificate and no fixed annual renewal — HSE guidance (ACOP L8) frames the duty as a risk assessment kept up to date, which for simple domestic systems can be a simple review.
Do I need an annual 'legionella certificate'?
No such statutory certificate exists, and the HSE has publicly warned against companies selling mandatory-sounding annual legionella certification for ordinary rentals. What you need is a suitable risk assessment, reviewed when circumstances change.
How often should the assessment be reviewed?
When there is reason to think it is out of date — for example changes to the water system, a change of use, or evidence controls aren't working. Periodic review is good practice; the law sets no fixed interval for domestic rentals.
What makes legionella risk higher in a property?
Stored water between about 20°C and 45°C, stagnation in little-used outlets or dead-leg pipework, open cold-water tanks, and spray-forming outlets like showers. Combi-boiler properties with mains-fed cold water are generally low risk.
What simple controls reduce legionella risk?
Hot water stored at 60°C or above, cold water kept cold, flushing outlets after void periods, descaling and cleaning showerheads, and insulating or removing redundant pipework. The assessment records which of these apply to your property.
Who can carry out the assessment in your area?
A competent person — which for a simple domestic system can be the landlord themselves if they understand the water system, or a contractor for assurance and documentation. Complex systems with tanks and long pipe runs justify professional assessment.
How long does a legionella risk assessment take?
Typically 30 to 60 minutes on site for an ordinary house or flat: the assessor traces the water system, checks temperatures and storage, and photographs the evidence for the written report.
What should tenants be told about legionella?
Simple advice: run showers and taps that haven't been used for a week or more before normal use, keep showerheads clean, and report water system problems. Giving this guidance in writing is an easy control measure to evidence.
Does an empty property increase legionella risk?
Yes — stagnant water in an unused system is the classic risk factor. Flushing all outlets thoroughly before a new tenancy starts is the standard control after a void period.
What does the written assessment include?
A description of the water system, identified risk points, the control measures in place or recommended, tenant advice, and the assessor's details and date — your evidence that the duty has been considered properly.
What if I ignore legionella duties?
The duty sits under the Health and Safety at Work etc. Act framework, so serious failures can be enforced by the HSE or your local council and prosecuted, with fines set by the courts. In practice, risk to tenants and insurance exposure are the immediate concerns.
Do I need laboratory water sampling?
Rarely for ordinary domestic rentals. Sampling is a tool for higher-risk or complex systems, or where controls appear to be failing. A standard rental in your area is normally evidenced by the risk assessment alone.
Are legionella duties different for HMOs?
The underlying duty is the same, but shared facilities, larger stored-water systems and licence conditions from your local council raise the bar in practice — HMO landlords more often use professional assessments and periodic reviews as licence evidence.
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