A written scheme of control is the document Regulation 8 of COSHH asks for once your risk assessment finds a foreseeable Legionella risk worth managing: it sets out how that risk is prevented or controlled, day to day, on your site [1]. The template below covers the eight sections an inspector expects to find. The worked example after it shows what each one looks like filled in.
Copy the headings. Replace the bracketed prompts with your own building’s detail. A scheme that names real outlets, real people and real pass marks beats a glossy generic one every time.
One thing to settle first: the scheme is not the risk assessment. The assessment finds the risk; the scheme is what you do about it. If yours reads like Legionella control in general rather than control of this water system, it is not finished.
The written scheme of control template
Each heading maps to something ACoP L8 and HSG274 expect a scheme to cover [1][2]. Treat the bracketed text as a fill-in prompt, not boilerplate to leave in.
1. System description and schematic. [A labelled schematic plus an asset and outlet register: cold water storage tanks, calorifiers/water heaters, TMVs, sentinel and infrequently-used outlets, showers, dead legs identified for removal.] If a reader cannot trace a named outlet in the scheme to a real tap on the wall, start here.
2. Roles and responsibilities. [Named duty holder, named Responsible Person and a deputy for each. Who logs temperatures, who reviews them, who signs off remedial work, and the competent contractor appointed for tasks beyond in-house skill.]
3. Safe operating regime. [The target conditions you keep the system in — hot water stored hot and distributed hot, cold water kept cold, no stagnation — with the figures your own risk assessment sets, not numbers copied from another site.]
4. Control measures and precautions. [Temperature control as the primary method; flushing of little-used outlets; TMV servicing; tank inspection and cleaning; showerhead cleaning and disinfection; dead-leg removal.]
5. Monitoring tasks, frequency and acceptable result. [Each routine check, how often, and the pass mark. Sentinel hot and cold outlet temperatures; tank and calorifier checks; TMV checks. Frequencies come from the risk assessment.]
6. Remedial action on loss of control. [For each check, what happens when a reading falls outside the acceptable range — who is told, what is done, and how the action is recorded and closed out.]
7. Records and review. [Where results are kept, how long they are retained, and the triggers that prompt a review: plant changes, occupancy changes, a positive sample, or a change of Responsible Person.]
8. Sign-off. [Date prepared, by whom, the Responsible Person’s acceptance, and the next scheduled review date.]
That is the skeleton. The value is in the detail you put on it, which is what the worked example demonstrates.
Worked example: a small office block (illustrative)
The following is an illustrative, composite example — not a real building — to show how the sections read once completed. Your figures must come from your own assessment.
System description. Three-storey office, mains-fed cold water to a roof tank serving WC outlets; a direct-fired water heater serving two kitchenettes and four TMV-blended washroom basins. Schematic ref OFF-01. The outlet register flags the third-floor shower and the rarely-used cleaners’ tap as infrequently used.
Roles. Duty holder: the managing director. Responsible Person: the facilities manager (deputy: the office coordinator). Monitoring: the office coordinator. Sign-off: the facilities manager. Tank cleaning and disinfection: an LCA-registered contractor [3].
Safe operating regime. Hot water generated and distributed hot; cold water kept below the cold limit your assessment fixes; no outlet left unused without flushing. The specific figures are taken from HSG274 as interpreted by the site risk assessment, not stated as universal law [2].
Monitoring, frequency, pass mark (illustrative).
| Check | Typical frequency | Acceptable result | If outside range |
|---|---|---|---|
| Sentinel hot outlet temperature | Monthly | Reaches the hot target within the dwell your RA sets | Re-check, log, raise to RP, investigate heater/circulation |
| Sentinel cold outlet temperature | Monthly | At or below the cold limit your RA sets | Identify warming cause, flush, raise to RP |
| Infrequently-used outlets flush | Weekly | Run to temperature, recorded | Missed flush escalates to RP; repeat misses trigger review |
| Calorifier/water heater check | Per RA | Operating at design temperature | Engineer call-out, log fault |
| TMV servicing | Per RA | Fail-safe and scald protection verified | Take out of service, arrange service |
Frequencies and figures above are illustrative; sentinel temperatures and monitoring intervals are set by HSE guidance and your own risk assessment, not by this page [2].
Remedial action. A cold sentinel reading above the limit is logged; the coordinator flushes and re-checks; if it persists the facilities manager investigates the cause and records the fix and the date it closed.
Review triggers. Refurbishment, a change of occupancy, a positive sample, or a new Responsible Person — any of which prompts a review before the next scheduled date.
How to use and record the scheme
A scheme only protects you if you can show it ran. The discipline is to write down the decision, not just the task: “the cleaners’ tap is flushed weekly because use is intermittent; a missed flush escalates to the Responsible Person.” That single sentence turns a chore into a defensible control, and it is the kind of detail an inspector reads for.
Tie every control in the template to dated evidence that it happened — the reading, the inspection, the clean, the exception and the action that followed [4]. For the deeper habits that hollow a scheme out, on documenting a written scheme of control is worth a read, and on ACoP L8 sets the legal frame the template sits inside.
The sections people skip
Three get left thin almost every time. Remedial action is the first — schemes list the check but never the “if it fails”, so a bad reading has nowhere to go. Infrequently-used outlets is the second; the rarely-touched shower or cleaners’ tap is the classic stagnation point and the one most often missing from the register. The third is review triggers — schemes get a periodic review date but no event triggers, so a refurb passes without anyone revisiting the document. In my view, fill those three properly and your scheme is already ahead of most.
A caveat worth stating plainly: this template is a structure to populate through a competent, site-specific risk assessment, not a finished compliance document and not legal or engineering advice. The temperatures, frequencies and remedial steps in your version must come from your own assessment of your own system — where it is complex, from a competent person — not from the illustrative figures above.
FAQ
Is the written scheme of control a legal requirement under Regulation 8?
Where your risk assessment identifies a foreseeable Legionella risk that needs controlling, Regulation 8 of COSHH and ACoP L8 expect you to prepare and implement a written scheme setting out how that risk is prevented or controlled [1]. A system assessed as so low-risk that no further action is needed may not require a full scheme, but that conclusion must come from a competent assessment and be recorded.
What is the difference between a written scheme of control and a logbook?
The scheme is the plan: the controls, who runs them, how often, and the pass marks. The logbook is the running evidence those controls were carried out and what happened when a result was out of range [4]. The scheme describes the routine; the log proves you followed it. You need both, and they should reference each other.
Can I just use a template without a risk assessment?
No. A template gives you the headings, but every figure, frequency and outlet has to come from a risk assessment of your specific system. A scheme populated with another building’s numbers is the generic document that fails on a close read.
Sources
[1] HSE, “Legionnaires’ disease. The control of legionella bacteria in water systems — Approved Code of Practice and guidance (L8)”. https://www.hse.gov.uk/pubns/books/l8.htm [2] HSE, “Legionnaires’ disease: Technical guidance (HSG274)”. https://www.hse.gov.uk/pubns/books/hsg274.htm [3] Legionella Control Association, “Code of Conduct for Service Providers”. https://www.legionellacontrol.org.uk/ [4] HSE, “Legionnaires’ disease — what you must do”. https://www.hse.gov.uk/legionnaires/what-you-must-do/index.htm