Short answer: a landlord has to assess the risk of legionella in the property’s water system, control it proportionately, review that, and be able to show what was done. That is the duty. It is not a certificate, and it is not automatically a monthly round of temperature readings in every property.
Where the confusion comes from is that the detailed guidance, HSG274, describes a full monitoring regime for the systems that need one. Reading that regime and assuming it all applies to a two-bed flat with a combi boiler is the most common mistake in this area, and it costs landlords time and money they did not need to spend.
The duty, in order
1. Assess the risk. Look at the actual water system: is there stored hot water, a cold water tank, a circulating loop, any part of the system that sits unused, any long runs that stay lukewarm? Are the occupants more vulnerable than average? The output is an assessment proportionate to what you found. HSE’s guidance for landlords is clear that most landlords can do this themselves and do not need to be professionally trained or accredited.
2. Control what the assessment found. For most simple systems the controls are unglamorous: keep hot water hot, keep cold water cold, remove or minimise parts of the system that hold stagnant water, and flush outlets that are not used.
3. Monitor, where monitoring is the control. Where temperature control is the control measure, that means taking readings at representative outlets on a schedule.
4. Keep it under review. HSG274 says to review regularly and whenever there is reason to think the assessment is no longer valid — after a boiler change, a bathroom reconfiguration, a long void, a change of occupancy. It does not set a fixed period, and neither should anyone quoting it at you.
5. Keep records. Where the statutory recording duty applies, L8 paragraph 72 says monitoring records should be kept for at least five years. HSE’s landlord guidance points out that the duty to keep records falls on employers with five or more employees, so many private landlords are not legally obliged to record anything. Keep records regardless: without them you have no way to show a control regime existed, and that is the position you do not want to be in.
When the monthly regime applies
Where a property does have stored hot water, circulation, a cold water tank or a communal system, HSG274 Table 2.1 indicates monthly checks at the following points:
| Check | Target | Run for |
|---|---|---|
| Hot water leaving the cylinder | 60 °C or above | — |
| Hot water returning to the cylinder, if it circulates | 50 °C or above | — |
| Hot sentinel outlets | 50 °C or above | one minute |
| Cold sentinel outlets | below 20 °C | two minutes |
Plus, alongside those:
- Weekly flushing of outlets not used for seven days or more, run until the temperature stabilises, and logged. Table 2.1 p78, para 2.78 p75, and para 2.144 p91 addresses rented dwellings specifically.
- Annual inspection of a cold water storage tank, inside and out, more often if debris or vermin are found. Table 2.1 p77, para 2.57 p70.
- A rotation of other outlets beyond the sentinels, so the whole system is profiled over time. The document names the practice but sets no period.
Sentinel outlets explains which taps those are, and what temperature hot water should be covers the thresholds and the boundary wording in detail.
The bit most landlords get wrong
Table 2.1 is described in HSG274 as an indication of frequency. The document is explicit that the risk assessment for the property determines what is actually monitored and how often (paras 2.79 p75 and 2.141 p90).
That cuts both ways, and honestly:
- A simple flat with a combi boiler, no stored water, no tank and occupants in normal health is a low-risk system. Its assessment may reasonably conclude that a small number of straightforward controls, checked occasionally, are proportionate. Monthly temperature rounds at four points are not automatically required.
- A converted house in multiple occupation with a communal cylinder, a long distribution run and periods when rooms sit empty is a different system entirely, and it may justify more than the table’s indication.
Nobody can tell you which of those your property is from a web page. That is what the assessment is for. HSE’s own guidance describes the risks in typical residential settings with small domestic-type water systems and regular water use as generally low.
What a good record looks like
The record is the part landlords most often under-do, and it is the part that matters when someone asks. HSG274 asks for records carrying the name of the person who took the reading, the date, and enough location detail to repeat the measurement (para 2.54 p70). L8 asks for records to be signed or otherwise authenticated (para 73).
In practice, a record that will stand up shows:
- Which outlet, described so a stranger could find it: “ground floor kitchen, hot mixer tap, furthest from cylinder”.
- The actual reading, not a tick. “51 °C” tells a story next year; “OK” does not.
- Who and when.
- What happened after a failure. A fail with an action and a recheck is better evidence of a working regime than a year of unbroken passes.
Legionella Logger exists for that last mile: it holds the schedule, times the one and two minute runs, judges each reading against the right threshold, records who took it, and exports the log as a PDF. It does not carry out or replace the risk assessment, and it does not make anything compliant. Those remain the landlord’s job.
Where to read the primary source
HSE’s own page for landlords is the right starting point, and it is short: legionella and landlords’ responsibilities. The detailed technical guidance is HSG274, and the Approved Code of Practice is L8. All are free to download.
If you have been told you need to buy a “legionella certificate”, read what a landlord actually needs before you pay for one.
Checked against the archived HSE PDFs of HSG274 Part 2 and ACoP L8 on 10 September 2026. Page numbers are the printed ones. Contains public sector information licensed under the Open Government Licence v3.0. This is general information about published guidance, not a legionella risk assessment and not legal advice. Plan CD is not affiliated with the Health and Safety Executive.