Legionella enforcement action: from improvement notice to prosecution
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Key points
- Enforcement is a ladder: advice, improvement notice, prohibition notice, Fee for Intervention, prosecution. Most duty holders meet it on the bottom rungs and go no higher.
- An improvement notice (HSWA section 21) requires a breach to be remedied by a deadline; an appeal within 21 days to an employment tribunal suspends it.
- A prohibition notice (section 22) stops an activity where there is a risk of serious personal injury; appealing does not suspend it.
- Ignoring a notice is a separate criminal offence, and is the most common route from a fixable problem to a courtroom.
- Real cases and outcomes are catalogued in the legionella enforcement tracker.
Legionella enforcement rarely starts in court. It starts with advice, escalates through formal notices with strict deadlines, and only reaches prosecution when the breach is serious, repeated or ignored. This page walks the pathway stage by stage: what each notice means, the deadlines that attach to it, and what to do if one arrives. For the penalties at the end of the road, see legionella fines and prosecutions.
The ladder at a glance
| Stage | What it is | What it costs you |
|---|---|---|
| Advice and letters | Informal direction after an inspection: fix these things | Time and the cost of the fixes; the letter stays on file |
| Improvement notice | Formal notice (HSWA s.21) to remedy a breach by a deadline | Compliance by the deadline; Fee for Intervention is likely alongside |
| Prohibition notice | Formal notice (s.22) stopping an activity where there is risk of serious personal injury | The system or building out of use until put right |
| Fee for Intervention | Cost recovery for the inspector's time where a material breach is found | An invoice at the regulator's hourly rate, growing with every hour spent |
| Prosecution | Criminal charges, usually under HSWA sections 2, 3 or 33 | Unlimited fines, possible imprisonment, and for directors, personal liability under section 37 |
Stage 1: advice and the letter
Most inspections end here. The inspector finds failings, a flushing list that was never written, a missing review date, and tells you to put them right, confirming it in a letter. This is not formal enforcement, but it is not nothing: the letter goes on file, it names a timescale, and if an inspector returns to find the same failings, the next step is formal. Treat the letter as a free notice and act on it while acting is still cheap.
Stage 2: the improvement notice
Where the inspector is of the opinion that you are breaching the law, or have breached it in circumstances making repetition likely, they can serve an improvement notice under section 21 of the 1974 Act. The notice must say what the breach is, which legal provision it offends, and the period within which you must remedy it. For legionella the content is usually mechanical: carry out a suitable and sufficient risk assessment, appoint a responsible person, implement a written scheme of control, or start and maintain monitoring records.
Two deadlines matter. The compliance period, stated in the notice, which you must meet or face prosecution for non-compliance. And the appeal window: within 21 days of service you may appeal to an employment tribunal, and appealing suspends the notice until the appeal is decided. Appeals are about law, not inconvenience; "we cannot afford it" is not a ground, but "no breach exists" or "the notice is defective" can be.
Stage 3: the prohibition notice
Where the inspector believes activities involve a risk of serious personal injury, a prohibition notice under section 22 can stop the activity immediately: a spa pool closed, a shower block taken out of use, a cooling system shut down. Unlike an improvement notice, an appeal does not suspend it; the prohibition bites while any appeal runs. That asymmetry is deliberate, and it tells you how the regulator views the risk at this stage: the activity stops first and argues later. The remedy is to fix the underlying condition, have it verified, and get the notice lifted.
Fee for Intervention: the meter that runs alongside
Where an inspector identifies a material breach, one serious enough to warrant formal action, the HSE recovers the cost of its time under Fee for Intervention, charged at an hourly rate for inspection, investigation and enforcement work. The invoice is independent of any notice and any later prosecution. A day of formalities can therefore carry a four-figure bill before any fine is even contemplated, which is part of why early compliance with advice is so much cheaper than late compliance with a notice.
Stage 4: prosecution
Prosecution sits at the top of the ladder, reached when the breach was serious, when harm resulted, or when lower rungs were ignored. Charges usually allege breaches of sections 2 or 3 of the 1974 Act, failing to protect employees or the public, with ACOP L8 and HSG274 as the standard the court measures against. Directors and managers can face personal charges under section 37 where an offence was committed with their consent, connivance or neglect. Sentencing follows the health and safety guideline: culpability, harm risked, and turnover set the band, and fines in legionella cases have run from thousands into the millions. The enforcement tracker records real cases, the failings behind them and the outcomes, and the pattern is consistent: the prosecuted organisation almost always lacked records, not just controls.
The cheapest point on the enforcement ladder is the first one. Every stage above advice costs more, proves less goodwill, and narrows your options. Act on the letter and the ladder ends there.
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.
If a notice arrives: the first week
Read the notice twice: once for what it alleges, once for what it requires and by when. Diarise the 21-day appeal window immediately, because it runs whether or not you have taken advice. Start the remedial work at once even if you intend to appeal part of the notice; tribunals and prosecutors both read early action well. Record everything: the work done, the dates, the contractor certificates, in the same log book the notice probably criticised. If the notice is wrong on the facts, put that in writing through the proper channel rather than arguing at the door. And if the alleged breach is genuine, fix it fully rather than minimally; a notice complied with on paper but not in substance is the fact pattern that turns one inspection into a prosecution file. The compliance checklist is a useful way to confirm the notice's ground is closed and nothing adjacent is left open.
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 is a legionella improvement notice?
An improvement notice is a formal legal notice, served under section 21 of the Health and Safety at Work etc. Act 1974, requiring you to remedy a specified breach within a stated period. For legionella it typically lists the failings found, such as no risk assessment or no monitoring records, and the date by which they must be put right. Complying ends the matter; ignoring the notice is a separate criminal offence.
How long do you get to comply with an improvement notice?
The notice itself states the compliance period, which varies with the work required. One constant is the appeal window: you have 21 days from service to appeal to an employment tribunal. Because an appeal suspends an improvement notice until it is decided, the compliance clock pauses if you appeal. A prohibition notice is not suspended by an appeal, so its effect continues regardless.
Can you appeal an improvement or prohibition notice?
Yes. Either notice can be appealed to an employment tribunal within 21 days of being served. The grounds are legal, not about convenience: for example that the inspector was wrong that a breach exists, or that the notice is defective. An appeal suspends an improvement notice but not a prohibition notice. A tribunal can cancel, confirm or amend a notice, so take advice before assuming the notice is final.
Does an improvement notice mean you will be prosecuted?
No. Most improvement notices are complied with and the matter ends there; the notice is the enforcement, not a step automatically leading to court. Prosecution follows where the breach was serious enough to charge anyway, where harm resulted, or where the notice is ignored. Failing to comply with a notice is itself an offence, so the most common route from notice to prosecution is simply not doing what the notice required.
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