What are the annual legionella checks?
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Key points
- The annual round centres on the calorifier: internal inspection or base drain-off for sludge, scale and corrosion.
- The same visit usually takes in TMV servicing, a shower head deep clean and a dead-leg sweep.
- The annual review audits the year's records: gaps, repeated failures and actions never closed out.
- The review asks whether anything changed that should trigger an early risk assessment review.
- Everything found and done is recorded in the log book and kept at least five years.
The annual legionella check is the deepest pass over the system: the calorifier is opened or drained from the base to look for a year of accumulated sludge and corrosion, valves due a yearly service get it, and the whole regime is reviewed, records, outlet lists and all, to confirm the written scheme still matches the building. Done properly it takes half a day to a day for a small premises, plus any contractor time. This walkthrough runs it in order.
Step 1: audit the year before you touch the plant
Start at the desk, not the calorifier. Pull the year's records from the log book and read them as an inspector would. Are the weekly flushes all there, or are there silent weeks? Did the monthly temperature round hit every sentinel outlet every month? Most importantly, follow every failed reading to its action: a failure with no recorded fix is the single most damaging thing an audit can find, because it shows the regime detected a problem and walked past it. Gaps found now become actions on the annual review record, not surprises in front of an inspector.
Step 2: the calorifier inspection
The calorifier stores hot water at 60°C or above, but its base runs cooler, and over a year that cold spot collects exactly what legionella likes: sludge, scale and corrosion debris. The annual inspection either opens the vessel or drains from the base valve to see what has built up. Stored and flow temperatures are confirmed at the same visit against the figures on the temperature chart. Significant debris means the vessel needs cleaning, and the method, date and result are recorded. The detail of what to look for is in calorifier inspection. This is usually contractor work; the responsible person's job is to make sure it happens, see the report, and file it.
Step 3: valves, showers and the dead-leg sweep
With the plant visit booked, the same window takes in the rest of the annual list. Thermostatic mixing valves on a yearly service interval are stripped, cleaned, descaled and failsafe-tested, see TMV servicing. Shower heads and hoses get their deep clean and descale if the quarterly cycle has not just covered it, see cleaning shower heads. And the building gets a slow walk with one question in mind: what has changed since last year? Removed fixtures leave capped stubs, refurbished rooms leave abandoned branches, and every one is a new dead leg that needs cutting back or adding to the flush list.
Step 4: review the scheme against reality
The last step is the review itself, and it is a comparison, not a formality. Does the little-used outlet list still match how rooms are actually used? Are the sentinel outlets still the nearest and furthest points after any plumbing changes? Have staffing changes left the responsible person role or its deputy uncovered? And the question that matters most: has anything happened this year, a change of use, building work, a positive sample, repeated temperature failures, that means the risk assessment itself is due for review rather than waiting for its usual cycle? How often a risk assessment is reviewed lists the trigger events.
The annual check is two jobs in one: open the plant and look inside it, then open the records and look inside those. A clean calorifier with a year of gaps in the log is still a failed review.
Free legionella risk assessment template
A structured Word document following the five-step approach in ACOP L8. Covers risk identification, written scheme, monitoring, and records. If it isn't written down, you can't evidence it.
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Sign it off and file it
The review ends with a written record: what was inspected, what was found, what was done, what actions remain and who owns them, signed by the responsible person. It joins the five years of records ACOP L8 expects, alongside the weekly flushes and monthly temperatures it just audited. The monitoring log sheets cover the year's working records; the annual review sits on top of them as the yearly summary. If the audit revealed that the regime itself is thin, that is the moment to rebuild it from the assessment up, and the risk assessment builder is the place to start. As with everything in the monitoring regime, the annual record evidences that the checks happened and the problems were chased. It records; it never certifies the system safe.
Free legionella risk assessment template
A structured Word document following the five-step approach in ACOP L8. Covers risk identification, written scheme, monitoring, and records. If it isn't written down, you can't evidence it.
Follows ACoP L8 and HSG274 Part 2. Free. No spam.
Frequently asked questions
What legionella checks are done annually?
The annual layer centres on the calorifier: an internal inspection, or a drain-off from the base, to check for sludge, scale and corrosion at the cold spot where legionella survives. Alongside it, the annual round is the natural moment to service thermostatic mixing valves where the scheme sets a yearly interval, deep-clean shower heads, sweep for new dead legs, audit the year's monitoring records, and review whether the risk assessment needs updating. Records of all of it go in the log book.
Do I need an annual legionella risk assessment?
Not necessarily. There is no fixed legal interval for the risk assessment itself; it is reviewed when there is reason to believe it is no longer valid, and many duty holders review it about every two years as good practice. The annual checks are different: they are the yearly inspection and regime review that the written scheme of control requires, whether or not the full risk assessment is due. The annual review is, however, the right moment to ask whether anything has changed that should trigger an earlier reassessment.
What is checked during an annual calorifier inspection?
The inspection looks at the inside of the vessel, either by opening it or by draining from the base, for the things that build up over a year: sludge, scale, corrosion and debris. The base matters most because it is the coolest part of the vessel and the place legionella can persist even in a system that stores at 60°C. Stored and flow temperatures are confirmed at the same visit. Significant debris or corrosion leads to cleaning, repair or further investigation, all recorded.
Who can carry out the annual legionella checks?
Competent in-house staff can do much of the annual round: the record audit, the dead-leg sweep, the review of the scheme. The calorifier internal inspection and TMV servicing are usually done by a competent contractor or plumber, because they involve isolating and opening plant. Whoever does each task, the responsible person owns the annual review and signs off that the regime as a whole is working and recorded.
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