It's one of the questions we get asked most, and the honest answer is "it depends". That's not much use on its own, so here's what the official guidance says, the situations that should prompt a review, and how most sensible duty holders handle it day to day.
December's a good time to think about it. Lots of offices, schools and shops are about to close for Christmas, next year's budgets are being set, and it helps to know whether a review needs to be in the plan.
There's no fixed expiry date
A Legionella risk assessment doesn't run out on a set date the way a landlord's gas safety record does. The HSE's Approved Code of Practice, L8, says the assessment should be reviewed regularly, and whenever there's reason to think it's no longer valid.
Older editions of L8 said to review at least every two years. That fixed figure was dropped when the current edition came out in 2013, in favour of "regularly, and when things change". You'll still hear "every two years" quoted a lot. As a rule of thumb it isn't a bad one, but it isn't the legal test. The real question is whether the assessment still describes your building, your water system and how it's run today.
When you should review straight away
L8 lists the kinds of change that should trigger a review. In plain English:
- Changes to the water system. A new boiler or cylinder, a tank taken out, refitted bathrooms, an extension, new pipework.
- Changes to how the building is used. An office turned into flats, a house becoming an HMO, a wing closed off, or occupancy dropping because of hybrid working. If more vulnerable people are now using the building, that counts too.
- New information about the risks or controls. Updated guidance, or finding out something about the system you didn't know before.
- Checks showing control has slipped. Temperatures out of range on your monthly checks, or a positive sample result.
- Changes to key people. A new responsible person, a new facilities manager or a change of contractor.
- A case of Legionnaires' disease linked to the system. That needs urgent action well beyond a paperwork review, obviously.
What "regularly" looks like in practice
For buildings where not much changes, most duty holders pick a review interval and stick to it. As a rough guide, this is what we commonly see:
- Simple, low-risk homes: every couple of years, or sooner if the property's been altered or stood empty for a long time.
- Offices, shops and HMOs: often every one to two years, depending on how complicated the system is.
- Care homes, healthcare and buildings with vulnerable users: usually more often, typically yearly, and tied into the Water Safety Plan.
Your assessor should give you a recommended review date in the report, based on your building rather than a one-size-fits-all rule. We always include one in ours.
Review or full reassessment?
A review doesn't always mean starting from scratch. If the building's the same, your records show temperatures are good and the actions have been done, a review can be fairly light: a site visit to confirm nothing's changed, a look through the logbook and an updated report.
If there have been big changes, like a new plant room, a change of use or a long closure, a fresh assessment makes more sense. A good assessor will tell you which one you need rather than selling you the bigger job.
Signs your assessment has gone stale
- It describes a tank, boiler or bathroom that isn't there any more.
- The named responsible person left a while ago.
- The actions list hasn't been touched since it was written.
- Nobody's quite sure where the monitoring records are.
- It was written before the building's use changed.
If you recognise one or two of those, it's time for a review whatever the date on the front says.
Don't forget the checks in between
The review is only part of the picture. Between reviews, the tasks in your written scheme still need doing and logging: monthly temperatures, flushing little-used outlets, cleaning shower heads, inspecting tanks. Those records are what tell you, and your assessor, whether the controls are actually working. If you'd rather not manage the routine checks yourself, our Legionella maintenance service takes care of them and logs everything.
Sampling has its place too, for example in healthcare settings or after a problem, but it's a snapshot rather than a substitute for a proper review. Our water sampling page explains when it's worth doing.
A quick word on the Christmas shutdown
If your building closes over the holidays, water will sit in the pipes for a week or two. That isn't normally a reason to redo the assessment, but your written scheme should say what happens. Typically that's flushing outlets before people come back and checking hot water temperatures once everything's running again. If your scheme doesn't mention closures at all, that's a hint it needs a look.
So, how often?
Regularly, and whenever something changes. For a stable, simple building, every two years is a sensible starting point. For anything complicated or used by vulnerable people, expect it to be more often. If you're a landlord wondering whether you need an assessment in the first place, start with our guide: do landlords need a Legionella risk assessment?
Not sure where you stand? Send us your current assessment and we'll tell you honestly whether it still does the job.