Legionella risk assessment: what landlords actually need
Legionella is the compliance topic with the biggest gap between what the law says and what landlords get sold. The duty to assess the risk is real. The 'legionella certificate' a letting agent insists you buy every two years is not. Here's what HSE actually requires, what you can do yourself, and when paying a professional makes sense.
By the FixQuotes editorial team
- Published
- Reading time
- 6 min read
Key takeaways
- Landlords have a legal duty to assess and control legionella risk in rented property, under the Health and Safety at Work etc. Act 1974 and COSHH.
- There is no such thing as a legally required legionella certificate, and water testing is not usually needed in domestic rentals. HSE says both, in terms.
- Most domestic rentals are low risk because water turns over constantly. A simple assessment, which a competent landlord can do themselves, is usually enough.
- No law sets a fixed renewal interval. The common 'every two years' rule is industry custom; HSE requires a review when circumstances change.
- The controls cost almost nothing: flush the system after a void, store hot water at 60°C, remove dead-leg pipework, and keep shower heads clean.
Do landlords legally need a legionella risk assessment?
Yes — but it's smaller than it sounds. Anyone who rents out residential property (even a room in their own home) has a duty to ensure the health and safety of tenants, which includes assessing and controlling the risk from legionella bacteria in the water system. The duty sits under the Health and Safety at Work etc. Act 1974, with the Control of Substances Hazardous to Health Regulations 2002 providing the control framework, and the Approved Code of Practice L8 giving the guidance. HSE's page on landlords' legionella responsibilities is the authoritative plain-English statement of it.
What the duty is not: a certificate scheme. HSE says directly that health and safety law does not require landlords to obtain or produce a 'legionella test certificate'. It also says most landlords can assess the risk themselves and do not need to be professionally trained or accredited to do it.
The reason the duty is light in practice: the risk in most domestic rentals is genuinely low. Hot and cold water gets used every day, so it doesn't sit stagnant at the warm temperatures legionella needs to multiply. HSE's words: a simple assessment may show there are no real risks and these are being properly managed, in which case no further action is needed.
What does a legionella risk assessment involve?
You're looking for places where water can sit warm and stagnant. Walk the property and note: where the cold water comes from (mains-fed is lower risk than a stored tank), whether the hot water cylinder stores water at 60°C, any redundant 'dead leg' pipework where water sits unused, outlets that rarely run (an en-suite in a spare room, an outside tap), and the condition of shower heads. Write down what you found and what you did about it — that written note is your risk assessment.
The controls are routine and nearly free: flush the whole system through before a new tenancy and after any void period, set the cylinder to store hot water at 60°C, have any dead-leg pipework removed next time a plumber is in, and advise tenants to clean and descale shower heads regularly. Tell tenants to report problems with the hot water — not just because it's a Section 11 repair, but because a failing cylinder thermostat is also a legionella control failing.
Water sampling and lab testing is not usually required for domestic hot and cold water systems — HSE says it's only needed in very specific circumstances, and its technical guidance HSG274 Part 2 covers the rare cases where testing is warranted. A company quoting routine annual water testing for a two-bed flat is selling you something the law doesn't ask for.
What does a professional assessment cost?
If you'd rather have it done professionally — common for portfolios, HMOs, or simply for the documentation — a domestic legionella risk assessment typically costs £75 to £200 per property in 2026, taking 30 to 60 minutes on site, with London and the South East 20 to 30% higher. Larger properties and HMOs with tanks and complex shared pipework sit at the top of the range or above it.
Be sceptical at both ends of the market. The £15 'certificate' sold online is unlikely to involve anyone competent looking at your water system, and at the other end, beware assessors whose report concludes you need their monitoring contract and quarterly testing. For a standard buy-to-let, the assessment is the product; recurring services need justifying against HSE's low-risk position.
HMOs deserve the professional version more often: stored cold water, long shared pipe runs, and outlets in void rooms all raise the real risk, and councils running HMO licensing may ask for evidence of legionella control at inspection — that's local licensing practice rather than an HSE certificate requirement, but the documentation answers both.
Where legionella fits in your compliance stack
Unlike the annual CP12 or the five-yearly EICR, there's no certificate to renew and no fixed clock — which is exactly why it gets either forgotten entirely or oversold. The right habit is to fold it into the tenancy-change routine: flush the system during the void, glance over the assessment while the property's empty, and update it if anything material changed. Our landlord responsibilities guide shows the full compliance picture in one place.
If a plumbing visit is what the assessment turns up — a cylinder thermostat fault, dead-leg removal, a tank that should be insulated — FixQuotes returns three quotes for the same job from vetted local plumbers, free for landlords and letting agents. Start at our plumbing repair quotes page.
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