England dutyholders: TMV removal policy with signed risk assessment
You can remove a thermostatic mixing valve, but only when a documented risk assessment shows the scalding risk at that outlet is insignificant, or when the removal is really a like-for-like replacement with equivalent or better fail-safe control. In healthcare and other high-risk settings, TMV3 units are rarely removed without formal, signed-off approval. Everything below sets out the regulatory basis, the decision framework and the checklist your written scheme needs to hold up under audit.
TL;DR:
Removal of a thermostatic mixing valve requires a documented risk assessment comparing scalding risk and legionella control, especially in healthcare settings.
Healthcare targets for TMV servicing are stricter, mandating annual checks for TMV2 and six-monthly checks for TMV3 with full commissioning and fail-safe testing.
Any change to the control scheme, including removal or temporary disconnection, must be reflected in the written scheme and involve signed approval by responsible personnel.
Plumbing alterations affecting TMVs may trigger notification requirements to water authorities, and skipped steps can create compliance gaps unrelated to legionella risks.
A structured operational process, including local isolation, disinfection, temperature verification, and thorough record-keeping, is essential to maintain safety and regulatory compliance.
Table of Contents
UK rules, guidance and dutyholder responsibilities that govern TMV removal
How to decide: a risk-based framework for when removal is acceptable
Operational steps: safe removal, temporary isolation and replacement workstream
Commissioning, in-service checks and servicing intervals after removal or replacement
Policy structure and copy-paste checklist for a TMV removal policy
How Bespoke Compliance Solutions can support your TMV removal policy and compliance work
UK rules, guidance and dutyholder responsibilities that govern TMV removal
TMV removal decisions in England sit at the junction of two duties that can pull in opposite directions: preventing scalds and controlling legionella. HSG274 Part 2 explains why this junction exists. TMVs blend hot and cold water to a safe temperature at the point of use, but that blended water sits in a temperature band where legionella can multiply if the valve, its pipework or its outlet are poorly maintained. HSG274 is explicit that fitting or removing a TMV must be informed by a comparative assessment weighing scalding risk against infection risk, not a decision made on convenience or cost alone.
For healthcare premises, the bar is considerably higher. HTM 04-01 and its D08 supplement require Type 3 TMVs at vulnerable-user outlets and prescribe detailed commissioning and in-service checking regimes to confirm the valve fails safely if either supply fails. The default expectation in these settings is retention, or immediate like-for-like replacement with TMV3-compliant hardware and full commissioning to HTM standards, never an unapproved gap in provision. HSE’s HSIS6 guidance reinforces this, noting that TMVs should sit close to the outlets they protect and that where a TMV is not fitted, an equally effective control must take its place.
Plumbing changes also carry water fittings obligations that are easy to overlook mid-project. WaterRegs UK guidance sets out notification duties to local water undertakers where plumbing alterations affect the supply, along with maintenance expectations for fittings in non-household premises. A TMV removal that changes pipework configuration, even temporarily, can trigger these notification requirements, and skipping them creates a compliance gap that has nothing to do with legionella but still lands on the dutyholder’s desk.
Underpinning all of this is the written scheme of control that ACOP L8 and HSG274 expect every dutyholder to maintain. A TMV removal, however brief, is a change to that scheme and needs to be reflected in it. In practice, your regulatory checklist for any removal decision should cover:
HSG274 Part 2: confirms TMVs create a blended-water environment and requires a comparative scalding-versus-legionella assessment before removal or fitting.
HTM 04-01 / D08 supplement: sets commissioning and in-service check requirements for TMV3 in healthcare, with removal treated as an exception rather than a routine option.
HSIS6 (HSE): confirms TMVs must sit close to the point of use and that equally effective controls are needed where none is fitted.
Water Supply (Water Fittings) Regulations / WaterRegs UK: covers fitting quality, notification duties to water undertakers, and maintenance frequency for non-household premises.
Written scheme of control: every removal, replacement or temporary isolation is a documented change, not a verbal decision.
How to decide: a risk-based framework for when removal is acceptable
The decision to remove a TMV should never be made by a single engineer on-site without a paper trail. HSG274 frames it as a comparative assessment, which means you are weighing two live risks against each other rather than ticking a single box. A practical framework looks like this:
Identify who uses the outlet and how. A basin in a staff kitchen carries a different scald risk profile to a bath used by a resident with reduced mobility or sensory impairment.
Classify the outlet type. Baths and showers deliver sustained, high-volume contact and generally warrant TMV2 as a minimum, with TMV3 reserved for higher-risk healthcare and social care settings per HTM 04-01.
Map the thermal plumbing context. Check hot storage temperature, delivery temperature at the outlet, the length of blended pipe runs and whether any dead legs exist that could harbour stagnant, warm water.
Weigh occupancy and frequency. An outlet used daily by vulnerable occupants needs a different judgement to a rarely used utility tap.
Decide on compensating controls if removal proceeds. These might include clear signage, supervised access only, temporary temperature warnings at the outlet, or a short-term increase in flushing frequency until a replacement is commissioned.
Record the decision and sign it off. An unsigned note in a maintenance log is not a risk assessment; it needs a named responsible person and a date.
TMV2 and TMV3 classifications matter here because they define the level of protection the valve is expected to deliver, not just its price point. TMV2 units meet the domestic and commercial standard for general use; TMV3 units add fail-safe performance validated for healthcare and similarly vulnerable environments. Removing a TMV3 and replacing it with a TMV2, or leaving the outlet unprotected, is not a like-for-like swap and needs the same scrutiny as full removal.
Some scenarios are effectively closed to a removal decision regardless of the paperwork. A TMV3 protecting a bath or shower in an operating hospital ward, care home or similar high-risk healthcare setting should not be removed without formal, documented approval from the responsible estates or infection control lead, in line with the HTM 04-01 supplement. Treat these as absolute no-go cases rather than judgement calls for a single contractor.
Pro Tip: Keep a one-page decision record template on-site so the responsible person can complete it in the moment, rather than reconstructing the reasoning from memory weeks later when an auditor asks for it.
Our guidance on reviewing a legionella risk assessment covers how to structure this kind of comparative judgement so it stands up to scrutiny, including how to weight vulnerable-user factors against infection control measures already in place elsewhere on the system.
Operational steps: safe removal, temporary isolation and replacement workstream
Once the decision gate is passed, the physical work needs its own discipline. Rushing the isolation or skipping disinfection is where most compliance gaps and infection incidents originate, not the decision itself.
Before any tools come out, the written scheme should be updated to reflect the planned change, and the responsible person should sign off the job. Confirm the contractor’s competence, check that any replacement TMV carries current WRAS or equivalent third-party certification, and hold the correct spare parts on-site before starting. If the plumbing change is significant enough to affect the local supply configuration, check whether WaterRegs UK notification to the water undertaker applies.
Isolation strategy affects both downtime and risk. Where the valve was originally installed with service isolating valves, or as a combined service-isolating TMV unit, the cartridge can often be removed and serviced without draining the wider system, cutting both disruption and the disinfection burden that follows a full drain-down. Specifying these combined units at design stage in commercial and healthcare projects is now common practice precisely because they avoid creating dead legs during maintenance work.
Key steps during the isolation and removal phase:
Isolate locally, not system-wide, wherever the installation allows it, to limit the volume of pipework exposed to stagnation.
Avoid creating new dead legs: capped or abandoned pipe stubs are a known legionella risk and should be removed, not left in place.
Put a temporary control in place immediately, such as a clearly labelled cold-only supply or a supervised-access notice, if the outlet cannot be fully isolated.
Flush and disinfect downstream pipework and the outlet fitting once work is complete, following your standard disinfection protocol.
Take bacteriological samples where the system has been open for an extended period, particularly after any drain-down affecting multiple outlets.
Practical guidance recommends servicing TMVs at least annually as a baseline, with more frequent servicing common in healthcare and other high-risk settings, which gives a useful benchmark for how often this kind of isolation work should be anticipated rather than treated as an emergency, according to LegionellaCheck.
Throughout the work, record inlet temperatures on both hot and cold feeds and the blended outlet temperature once reinstated, then verify the fail-safe function operates correctly if either supply is interrupted. These readings, along with the commissioning date and the name of the person who signed it off, go straight into the site logbook. Our temperature monitoring checks guidance sets out the exact readings worth logging and how to structure that record so it is usable months later, not just on the day.
Commissioning, in-service checks and servicing intervals after removal or replacement
A TMV that has been removed and reinstalled, or replaced outright, is not compliant again until it has been properly commissioned and the paperwork exists to prove it. This is where many sites fall down: the physical work is fine, but the audit trail is thin.
Commissioning paperwork should record the set point the valve has been commissioned to, the inlet temperatures on both hot and cold feeds at the time of commissioning, the date, and the name and signature of the person who carried it out. Without this, you cannot demonstrate the valve was ever brought into safe service, regardless of how well the physical installation was done.
For TMV3 units, HTM 04-01 prescribes a short-term checking schedule immediately after commissioning, before settling into a routine interval, alongside a fail-safe test that confirms the valve shuts down or defaults to a safe temperature if either the hot or cold supply fails. Skipping this step-down period is one of the more common gaps found during healthcare estates audits.
A sensible servicing regime looks like this:
Set a risk-based baseline of at least annual servicing for standard commercial and non-healthcare sites, per LegionellaCheck’s practical guidance.
Move to six-monthly servicing for healthcare and other high-risk settings, reflecting the tighter tolerances HTM 04-01 sets for TMV3.
Include the core service tasks every time: clean and descale the valve, disinfect as required, check and clear strainers, run a fail-safe test and record the result.
Log blended temperature drift against the commissioned set point, flagging anything beyond roughly a 2°C shift for further investigation rather than waiting for a full failure.
File the service record alongside the commissioning certificate, not as a separate, disconnected document.
Pro Tip: A drift of more than around 2°C from the commissioned blended temperature is a useful trigger point for scheduling an out-of-cycle service, rather than waiting for the next annual or six-monthly date to come round.
Sites that automate temperature capture between services tend to catch this drift earlier, since manual spot checks only see a snapshot rather than the full pattern between visits.
Policy structure and copy-paste checklist for a TMV removal policy
A TMV removal policy only earns its keep if it is short enough to actually be used on-site, while still covering every decision point an auditor will ask about. The following structure works across commercial, healthcare and housing sites, with detail scaled to the setting.
Your policy document should include these sections:
Purpose and scope: what the policy covers and which sites or valve types it applies to.
Responsibilities: who holds authority to approve a removal, and who carries out the physical work.
Decision gate: the risk assessment template used to weigh scalding risk against legionella risk before any removal proceeds.
Notification and approval: who must be told before work starts, including water undertaker notification where WaterRegs UK requirements apply.
Temporary controls: the compensating measures permitted while a valve is out of service, and how long they may remain in place.
Commissioning and servicing requirements: the checks required before an outlet is returned to normal use.
Record retention and training: how long records are kept and who needs awareness training to recognise when a removal decision needs escalating.
For the site logbook itself, a shorter operational checklist covers the practical sequence:
Stage | Action | Evidence to record |
Pre-work | Update written scheme, sign-off by responsible person | Signed decision record, contractor competence check |
During work | Isolate, avoid dead legs, apply temporary controls | Isolation method, temporary control notice, photos |
Disinfection | Flush and disinfect downstream pipework | Disinfection method, sample results where taken |
Recommissioning | Set and verify blended temperature, test fail-safe | Commissioning certificate, inlet/outlet temperature readings |
Aftercare | Schedule next service, file all records together | Service interval logged, logbook updated |
Retention matters as much as collection. Commissioning certificates and service records should be kept for the life of the installation, not just until the next audit cycle, since inspectors and insurers alike may ask for a history going back several years. The minimum audit trail is the commissioning certificate, the risk assessment extract that justified any removal, the service records with inlet and outlet temperature logs, and the fail-safe test results, all filed together rather than scattered across separate systems.
How a specialist provider approaches TMV removal policy
Some specialist providers build TMV removal decisions around bespoke legionella risk assessments tailored to different site types, rather than applying generic templates regardless of setting. Because the assessment is specific to the site, the outcome for a housing association bathroom and a hospital ward outlet can differ substantially even where the valve type is identical.
The risk assessment sets the service interval and the commissioning checks required for each outlet, feeding directly into the written scheme rather than sitting as a standalone document. Where a TMV servicing job on a live site reveals a valve that needs removal rather than repair, the same risk assessment framework is used to decide whether temporary controls are sufficient or whether the outlet needs to be taken out of use entirely until a replacement is commissioned. On sites with automated temperature monitoring already installed, that same monitoring data often confirms the compensating controls were effective while the valve was out of service, giving auditors a continuous record rather than a gap in the logbook.
This approach reflects the wider method described in our Legionella Compliance Method of Works, which sets out how risk assessment, remedial works and ongoing monitoring are meant to work as a single, connected process rather than separate jobs booked in isolation.
What the guidance gets right, and what it leaves out
Most TMV guidance focuses heavily on the engineering, valve types, fail-safe mechanisms, commissioning tolerances, and treats the decision to remove one as an afterthought. That gets the emphasis backwards. The engineering is well understood and rarely the point of failure; the decision gate is where sites actually go wrong, because it is the one step that depends on judgement rather than a spec sheet.
The overrated part of most advice is the assumption that a TMV is either compliant or not, a binary switch. In practice it is a continuous risk judgement that shifts with occupancy, outlet type and what else is happening on the system, which is exactly why HSG274 frames it as a comparative assessment rather than a fixed rule.
If you take one thing from this, prioritise the paper trail over the plumbing. A well-executed removal with no signed risk assessment behind it is indefensible at audit, while a slightly slower job backed by a clear, dated decision record protects both the occupants and the dutyholder.
— Sammi
How Bespoke Compliance Solutions can support your TMV removal policy and compliance work
Getting the decision right matters more than getting it done quickly, and that is where a second, independent set of eyes on the risk assessment tends to pay for itself. Bespoke Compliance Solutions carries out Legionella Risk Assessments from £185 one-off, giving you the documented, signed-off justification a TMV removal decision needs before any work starts.
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For the physical work itself, our Thermostatic Mixing Valve (TMV) Servicing covers removal, replacement, commissioning and the fail-safe testing your written scheme needs on file. Where a site wants continuous evidence that compensating controls held up while a valve was out of service, Automated Water Temperature Monitoring gives you that record without relying on manual spot checks. If a removal job involves drain-down or system disinfection, our water tank cleaning and system disinfection services cover that stage, and where samples are needed afterwards, our water testing and analysis service, including Pseudomonas aeruginosa and TVC testing, can confirm the system is clear before the outlet goes back into use.
Get in touch to arrange a survey or request a quote, and we will scope the right combination of assessment, servicing and monitoring for your site.
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FAQ
Is a TMV a legal requirement in England?
There is no blanket legal requirement to fit a TMV on every outlet, but dutyholders must control scalding and legionella risk under health and safety law, and HSG274 treats TMVs as a standard control where the risk assessment identifies a need for one. In healthcare settings, HTM 04-01 effectively mandates TMV3 at vulnerable-user outlets.
What are the TMV servicing regulations in the UK?
There is no single statutory servicing interval written into law, but practical guidance recommends servicing TMVs at least annually as a baseline, moving to six-monthly in healthcare and other high-risk settings, according to LegionellaCheck. Healthcare sites must also follow the commissioning and in-service check regime set out in the HTM 04-01 D08 supplement.
Do I need a TMV with a mixer tap?
Whether a mixer tap needs a TMV depends on who uses the outlet and the scalding risk your risk assessment identifies, not the tap style itself. A standard mixer tap in a low-risk, general-use setting may not need one, while baths and showers used by vulnerable occupants typically warrant TMV2 as a minimum under the framework set out in HSG274.
How can I clean a thermostatic mixing valve?
Cleaning a TMV involves isolating the supply, removing and descaling the cartridge, disinfecting the housing and checking the strainers for debris before reassembly. This should be done as part of a scheduled service that also includes a fail-safe test and a record of the inlet and blended outlet temperatures, following the core tasks set out in LegionellaCheck’s servicing guidance.
Can a facilities team remove a TMV without a formal risk assessment?
No. HSG274 requires that any decision to fit or remove a TMV be based on a documented comparative assessment of scalding versus legionella risk, and in healthcare settings the HTM 04-01 supplement sets an even higher approval threshold. Removing a valve without this evidence leaves the dutyholder unable to demonstrate compliance if the decision is later questioned.
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