What is HTM 01-05 and what does it mean for dental waterlines?
On this page
Key points
- HTM 01-05 (2013) is the decontamination guidance for primary care dental practices, including dental unit waterlines; the CQC inspects against it.
- HTM 04-01 is the separate guidance for the building's water system. A dental practice works to both.
- Dental unit waterlines are a known weak point: narrow-bore, warm, stagnant water and biofilm.
- The regime is flushing, disinfection per the manufacturer's instructions, anti-retraction valves, and records.
- There are no dental-practice legionella prosecutions in the HSE public convictions register; enforcement runs through CQC inspection, so compliance is evidenced by records, not by waiting for a court case.
HTM 01-05 is the Department of Health guidance on decontamination in primary care dental practices (2013). For legionella it matters because it governs the dental unit waterlines, the narrow tubes feeding the drill and syringe, while HTM 04-01 governs the building's wider water system. Dental practices work to both.
Dentistry has a doubled water-safety problem that most guidance pages miss. The practice building is an ordinary healthcare water system, covered by the same legionella duties as any premises. But each dental chair carries its own miniature water system, the unit waterlines, with conditions legionella loves: warm, still, narrow-bore and coated in biofilm. This page explains which document covers which half, and what the waterline regime looks like in practice. For the full practice-wide assessment, see legionella risk assessment for dental practices and the dental risk assessment template.
What HTM 01-05 is
HTM 01-05, Decontamination in primary care dental practices, was published by the Department of Health in 2013. Its main subject is instrument decontamination, the cleaning, sterilisation and storage of reusable instruments, but it also sets expectations for the water feeding the dental unit. It is guidance, not an Act of Parliament, but it carries regulatory weight because the Care Quality Commission inspects registered dental providers against it. A practice that cannot evidence its waterline regime has a CQC problem even where nobody has been harmed.
HTM 01-05 versus HTM 04-01
The two documents are frequently confused, and the distinction is the core of dental water safety:
| Document | Scope | What it expects |
|---|---|---|
| HTM 04-01, Safe water in healthcare premises | The building's hot and cold water system: incoming main, storage, calorifiers, outlets | The healthcare legionella regime: risk assessment, written scheme, temperatures (stored hot at 60°C, 55°C at outlets), monitoring and records |
| HTM 01-05, Decontamination in primary care dental practices | Decontamination processes, including the dental unit waterlines inside each chair | A written waterline management regime: flushing, disinfection, anti-retraction valves, and maintenance per the manufacturer's instructions |
HTM 04-01 explained covers the building side in detail. The rest of this page is about the waterlines.
Why dental unit waterlines grow legionella
A dental unit waterline is a few metres of narrow-bore plastic tubing carrying water to the handpiece, air-water syringe and scaler. Three features make it a legionella-friendly environment. The bore is narrow, so the surface-to-volume ratio is high and nearly all the water touches the tube wall. The water sits near room or body temperature and stands still for most of the day and all night. And the tubing develops a biofilm, the slime layer that shelters and feeds bacteria, within days of first use. Published studies have repeatedly found legionella and high bacterial counts in dental unit waterlines, which is why the guidance treats the lines as a system in their own right rather than an extension of the tap.
Anti-retraction valves matter for the same reason: without them, the pressure drop when a handpiece stops can suck oral fluids back into the line, seeding the biofilm with exactly the nutrients and organisms it thrives on.
The waterline regime in practice
HTM 01-05 expects a written regime set against the chair manufacturer's instructions. In practice, the elements are:
- Flushing. Run the lines to drain at the start and end of each clinical session and between patients. The commonly taught figures are around two minutes at the start and end of the session and 20 to 30 seconds between patients, but the manufacturer's specified times take precedence.
- Disinfection. Many units run a continuous low-level disinfectant dosing system, or periodic disinfection cycles, using a product the manufacturer approves for the unit. Self-contained bottled water systems make dosing and draining easier to control than direct mains feeds.
- Anti-retraction devices, fitted and maintained so backflow into the line cannot occur.
- Records. Each flush, dose and disinfection cycle is logged, so the regime is evidenced rather than asserted.
- Sampling where specified, as part of the practice water hygiene plan, particularly after extended closure or where flushing compliance has been poor.
The building water system and the dental unit waterlines are two systems with two guidance documents. HTM 04-01 covers the first; HTM 01-05 covers the second; the practice needs written, recorded regimes for both.
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.
How enforcement actually works for dental practices
Worth knowing: the HSE public convictions register contains no dental-practice legionella prosecutions in the years we reviewed, and our enforcement dataset has no dental case to report. That is not evidence the risk is unreal; it reflects the enforcement route. Dental practices are regulated through CQC registration and inspection against HTM 01-05, so the consequence of a missing waterline regime is an inspection finding, a requirement notice or a registration condition, not a crown court fine. The practical lesson is the same as everywhere else in legionella control: the regime has to be written down and recorded, because the record is what the inspector asks for.
Where to go next
For the building-wide duties, start with the legionella risk assessment guide and the training page, which includes dental waterline training. For the practice as a whole, the dental practices building-type page and the dental template with worked example pull both halves together. As ever on this site: these pages explain and record; they do not certify any practice as compliant.
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 HTM 01-05?
HTM 01-05 is the Health Technical Memorandum on decontamination in primary care dental practices, published by the Department of Health in 2013. It sets the standards dental practices in England are expected to meet for decontamination, including instrument reprocessing and the management of dental unit waterlines. The CQC inspects dental providers against it as part of registration, so it is the reference point for dental infection control even though it is guidance rather than a statute.
What is the difference between HTM 01-05 and HTM 04-01?
They cover different systems. HTM 01-05 governs decontamination in dental practices, including the waterlines inside the dental chair unit. HTM 04-01, Safe water in healthcare premises, governs the building's hot and cold water system, the same legionella regime other healthcare premises follow. A dental practice needs both: HTM 04-01 for the incoming supply, storage and outlets, and HTM 01-05 for the chair-side waterlines that feed the handpieces and syringes.
How often should dental unit waterlines be flushed?
Follow HTM 01-05 and the chair manufacturer's instructions. The commonly taught regime is to flush at the start and end of each clinical session, for around two minutes, and for 20 to 30 seconds between patients, using anti-retraction valves so oral fluids are not drawn back into the line. Whatever regime the manufacturer specifies should be written into the practice's procedures and recorded, so the flush log evidences what was done.
Do dental unit waterlines contain legionella?
They can. Dental unit waterlines are narrow-bore plastic tubes holding water near body temperature that stands still for most of the day, which is ideal for biofilm. Published studies have found legionella and other organisms in dental unit waterlines, including at otherwise well-managed practices, which is exactly why HTM 01-05 requires a written waterline management regime of flushing, disinfection and, where specified, sampling rather than assuming the mains water keeps the lines clean.
Do dental practices need a legionella risk assessment?
Yes. A dental practice is a workplace with a water system, so the general duties under the Health and Safety at Work Act, COSHH and ACOP L8 apply to the building water system just as they do to any premises, and HTM 04-01 applies as healthcare guidance. On top of that, HTM 01-05 expects the dental unit waterlines to be managed as their own sub-system. Our dental practice page and dental risk assessment template cover both halves.
Related water hygiene products and services from trusted UK providers will appear here.