Here's the list of relevant Healthcare regulations and guidance that Horne thermostatic mixing valves, taps and showers are designed to comply with. Click on the + to expand each topic below.
NB: Health Guidance Note: Safe hot water and surface temperatures (published in 1998 by NHS Estates) has been superseded by HTM 04-01 and SHTM 04-01 in Scotland. However, the comment on safe surface temperatures has been, in our opinion erroneously, omitted from both new documents. Note that the 1998 Welsh Health Estates (WHE) HGN of the same name still applies.
Published in 2012, the HSE document Managing the risks from hot water and surfaces in health and social care details how vulnerable people may be exposed to hot temperature when bathing or showering, or where there are hot surfaces such as pipes or radiators.
To reduce the risk of scalding, the document states that outlets that may be accessible to vulnerable people, and where there is the potential for whole-body immersion (baths and showers), the discharge temperature should never exceed 44°C.
There is also risk of injury from hot surfaces, such as hot water pipework, radiators and their associated pipework. Contact with surfaces above 43°C can lead to serious injury, especially if the contact is prolonged due to an inability to move (perhaps from a fall or being trapping by furniture). High surface temperatures should be well out of reach (not within 2 metres of finished floor level (FFL) was recommended in the 1998 HGN). Within reach surfaces should, therefore, not exceed 43°C.
Users of Horne surface mounted shower panels are protected from the hot surface temperature (~ 60°C) of the hot water supply pipe, which is safely enclosed within the aluminium panel. The Optitherm Thermostatic Tap is usually mounted at approximately 1m from FFL and therefore could become a 'touching' surface by vulnerable patients. The Optitherm has been specifically designed such that its surface temperature never exceeds 42°C and this has been demonstrated using a thermal imaging camera.
BS 7942:2011 and the (2017) Supplement to HTM 04-01
Performance specification D 08: thermostatic mixing valves (healthcare premises)
This is a Model Engineering Specification that was developed to ensure that thermostatic mixing valves (TMVs) and thermostatic showers used in healthcare settings achieved a minimum performance standard.
It specifies the 'performance, material requirements and test methods for thermostatic mixing valves for use in care establishments where the users, by virtue of their physical or mental condition, are deemed to be of greater risk of injury in their use of domestic hot water than would be the case for normally able persons in their own dwelling' (Section 1.0 Scope, para 1).
WRAS Approval (and BS 6920 compliance) is a pre-requisite to D 08 approval.
Designation. Determined by the TMV's intended application, pressure parameters (HP/LP) and maximum mixed water temperature at the point of discharge.
The testing of thermostatic mixing valves under D 08 applies to TMVs with or without integral on/off control and also user-adjusted or pre-set temperature control.
The first test determines the Leak Tightness of the mixing valve, its integral check valves, obturator (on/off control) and any diverter, if present. Essentially this is a high (static) pressure test to identify any weakness, shown in seepage through the walls or closing surface, of each component and also to test the effectiveness of the anti-backsiphonage devices (check valves).
Durability testing subjects the on/off and diverter mechanisms, if present, to 50,000 opening and closing movements at the appropriate Designation pressure and standard temperatures. During and following the test, there should be no leakage, deformation or failure of any component.
Durability testing of the thermostat involves 30,000 ± 200 cycles of accelerated operation (draw off after a period of non-use, or 'ambient-start') to represent normal operating conditions. During and following the test, the output temperature must remain at the valve's initial temperature setting ± 2K.
The durability test also serves to pre-condition (exercise) the thermostat ahead of the thermal performance part of the test procedure.
Performance testing of the TMV or shower valve monitors the sensitivity and stability of its temperature control under changing supply flow rates, temperatures and pressures. At (ambient) start-up and, perhaps, on adjustment of the mixed water temperature, there will be a temperature overshoot or transient. The test determines the characteristic and duration of any transient spike (the greater the temperature rise the shorter the allowed duration). The thermal shut-off test determines how the valve responds to a complete and sudden failure of the cold water supply. The thermostat element, bathed in pure hot water, quickly expands, moving the slide valve to close upon the hot valve face thus stopping the flow). The test records the transient rise in the mixed water temperature as well as the maximum rise under a prolonged CW supply failure. The valve is also monitored over a sudden restoration of the CW supply to determine the characteristics of any transient rise and the temperature to which the mixed water returns. The same tests are carried out for a complete and sudden failure (and restoration) of the hot water supply and the valve's response.
To check our approval status, please visit BuildCert TMV3 Approved List and type Horne into the search field.
Safe Water in Healthcare Premises. Part A (Design, Installation & Commissioning), Part B (Operational Management), Part C (Pseudomonas Aeruginosa – Advice for Augmented Care Units) and recent Supplement Performance specification D 08: thermostatic mixing valves (healthcare premises) (see entry above)
This document describes how water systems in healthcare buildings should be designed, operated and maintained to prevent the proliferation and transmission of pathogenic micro-organisms and thus reduce the incidence of nosocomial infection.
Historically published for the control and management of Legionella Pneumophila in healthcare water systems, the document has recently been expanded to cover additional pathogens such as Pseudomonas Aeruginosa, Stenotrophomonas Maltophilia and Mycobacteria.
Unlike L. Pneumophila, which infects the lungs via inhalation of contaminated micro-droplets of water, Pseudomonas Aeruginosa can spread by contact and via contaminated water: from patient-patient, patient-outlet, and outlet-patient. As such, additional investigation needs to be carried out to determine the reservoirs of the pathogen and appropriate interventions put in place. Poor system design and (lack of) maintenance (system and component) are key factors in Legionella proliferation whereas P. Aeruginosa, which is described as an opportunistic pathogen, can colonise the water system by retrograde contamination, inhabiting in particular the last 2 metres before the tap. Retrograde contamination can occur by a number of means and, in high use areas, it is almost inevitable that colonisation will occur at some point during the lifetime of the fitting.
The new document also brings in the concept of a Water Safety Group (WSG); a committee of people from the disciplines of Engineering and Facilities Management (Estates), Microbiology and Infection Prevention and Control (IPC), Housekeeping (soft FM), procurement and other relevant stake-holders. A more holistic approach to healthcare water management is advocated; defining the remit of the WSG and its role in developing a site-wide Water Safety Plan (WSP), a risk-management approach to water safety. This should be a living document under continual review and adaption.
Horne products are designed with close consideration for the regulatory requirements. Integration of components and specialised features facilitates customer’s compliance whilst also offering cost savings (fewer components, fewer connections to make up, shorter installation time):
Servicing valves are available as integrated components across the point-of-use range and these facilitate performance testing, isolation for maintenance and other processes described later.
Part A, para 10.56: Service isolation valves should be fitted to all pipework preceding sanitary tapware, WCs etc for servicing, repair or replacement.
In-line strainers are integrated into all Horne point-of-use TMVs, taps and shower valves. The mesh size is optimised to protect the downstream thermostatic mechanism from particulate matter. The strainer is a basket type and is specifically designed for its large surface area – collecting particulates and debris but minimising flow restriction, unlike disc strainers that block easily.
Part A, para 10.53: ...In-line strainers should be fitted within the water pipework system to protect vulnerable valves and fittings against ingress of particulate matter. The installation of these fittings should allow adequate access for maintenance/replacement and they should be provided with a means of upstream isolation [see servicing valves above]. Strainers can be a source of microbial contamination including Legionella and Pseudomonas Aeruginosa and should be included in routine cleaning, maintenance and disinfection.
Removing the basket strainer from the valve inlet assembly (perhaps for cleaning and disinfection) provides access to the hot and cold water supplies – providing a drain or sampling point:
Part A, para 12.2: Within the system, it is essential to include facilities for measuring [temperature/pressure or sample collection], regulating, isolating, venting, draining, and controlling the flow of water.
D 08 Supplement, Chapter 11 Commissioning, para 18.104.22.168: Record the temperature and the pressure of the hot and cold water supplies adjacent to the TMV.
This drain point also facilitates Elevated Velocity Flushing, a requirement ahead of valve and system commissioning to purge the pipework of particulate matter, swarf and other construction debris.
Part A, para 15.5: The system should be flushed to remove all flux and debris before being filled with water...
Cross-flow of the water supplies is prevented via a single check valve on each inlet to the thermostatic mixing, shower or tap valve.
Part A, para 9.10: If unequal pressures exist in the hot and cold water supplies to combination taps where water mixes in the body of the tap, a single check valve is required on each feed pipe to the tap to prevent backflow of water from one to the other.
In the case of the Optitherm thermostatic clinical tap, its design was fully determined by the change, in 2006, to the HTM 04-01 document. The 2016 edition reiterates:
Part A, Chapter 10, Table 2, Note 1: Where installed, it is preferable that thermostatic mixing devices are fitted directly to the mixed temperature outlet or be integral with it, and be the method of temperature and flow control, i.e. the mixing device should not be separate nor supply water via a second tap or manual mixer since there will be many cases where draw-off of cold water will not occur.
With this instruction, our design engineers set about integrating our highest specification TMV, the Horne 15 4th Connection, with a tap body that was optimised for ease of cleaning and maintenance, and effective hand hygiene (dual lever arrangement). The 4th connection provides a bypass of the thermostatic valve to enable its dual function – warm, thermostatically controlled, mixed and also dedicated cold water delivery.
Good turnover of water is important to reduce stagnation and maintain water quality. Valves that serve a dual function therefore improve water turnover due to increased usage and capacity. The Horne Optitherm is both a mixed water tap and a dedicated cold water tap: for every operation, delivering either mixed or cold water through the outlet will draw cold water to drain and increase turnover. The dual mode TSV1 shower also benefits from increased usage/capacity as it can be utilised by ambulant and non-ambulant users.
Part A, para 12.6: Pipework in buildings should be designed and routed in a manner that will provide good turnover of water, particularly in cold water service systems.
Part B, para 7.43: The most effective management of showers will be achieved by the removal of unnecessary ones and the regular use of others.
With the exception of a handful of Horne shower models that are aimed at the leisure and education markets, Horne showers only feature single function shower heads with no means to adjust the spray pattern (for example by moving two orifice plates relative to each other).
Part A, para 10.61: The flow of some showerheads can be adjusted by selecting different sets of nozzles (fine spray, pulsating plow etc); as this will exacerbate possible stagnation problems, they should not be installed in healthcare premises.
The outlet fitting on the Optitherm thermostatic tap is a critical component (more detail in our series of blog posts on the subject). It regulates the flow to reduce splashing, conditions the flow such that it falls in a straight, clean and uninterrupted column, also to reduce splashing. It also prevents the fitting from draining down following usage (and those unsightly dribble marks) – exchanging water for contaminated air in a dark, moist, high-surface area environment. This reduces the severity of retrograde contamination.
Part A para 10.57 Note: Spray type mixer taps are not recommend in healthcare premises; therefore, the type of tap should be selected to minimise the formation of water droplets and aerosols. Water flow profile should be compatible with the shape of the wash-hand basin to avoid splashing.
Part B, para 7.44: It is important to note the difference between self-purging and self-draining showers. Self-purging showers can be an effective Legionella control procedure, while self-draining showers can support the proliferation of Legionella.
HBN 00-09: Infection Control in the Built Environment (supersedes and replaces all versions of Health Facilities Note 30 HFN 30).
This document deals primarily with the increasing need to design-out potential reservoirs of infection prior to building any new or refurbishment healthcare facilities. It advocates collaboration between design teams and infection prevention and control teams to select products and to design layouts that optimise the requirements for each team whilst minimising compromise. Adherence to the Water Safety Plan, a risk management approach to the microbiological safety of water, is required as is good practice in local water distribution and supply.
The document provides guidance to Infection Prevention and Control (IPC) teams regarding the project planning process and their contribution for ‘designed-in IPC measures’ at every stage of the design process from initial concept through to outline and detailed design. It promotes awareness of all relevant and current healthcare regulations and partnership between the various client-side stakeholders (IPC, Hard and Soft FM, budget holder) and the design team. It also provides guidance to inform designers about healthcare-associated infectious pathogens, reservoirs and transmission of infection within the healthcare built environment.
The document gives IPC teams higher authority on the design process and suggests that they must ‘ensure that the designers/planners recognise the benefits of not cutting corners on IPC issues’ (para 2.14). Similarly, in respect of PFI contracts, ‘the IPC team will need to make sure that certain criteria are embedded into the contract in such a way that important decisions on design or build do not go ahead without being signed off by them’ (para 2.18).
More specific information with respect to IPC is provided for the selection of M & E plant and services and also fixtures and fittings required within the facility.
Water Fittings (General)
The requirement that all water fittings must not support microbiological growth through approval to the Water Supply (Water Fittings) Regulations 1999, i.e. WRAS approval is reiterated in this document and others. The unnecessary use of flexible hoses should be avoided but where unavoidable they should be constructed of a WRAS approved alternative to EPDM (Para 3.189-190).
Hand Hygiene Facilities
Para 3.46: Health and Safety regulations require that both hot and cold running water should be available in areas where employees are expected to wash their hands [The Workplace (health, safety and welfare) Regulations 1992].
This also applies to clinical handwash and is met by the dual function (mixed warm and dedicated cold water delivery) of the Optitherm thermostatic tap.
Para 3.47: Hands should always be washed under running water; mixer taps allow this to be practiced safely in healthcare settings where hot water temperatures may be higher to control Legionella (HTM 04-01).
The Optitherm is a combined thermostatic mixing valve, warm water and dedicated cold water tap. The integral thermostatic valve is TMV3 Approved and thus meets the requirements of D 08 Model Engineering Standard (HTM 04-01 Supplement).
Para 3.51: Swan neck tap outlets are not recommended as they do not empty after use...
This statement is, in our opinion, only partly true. The design of the swan neck tap allows for some of the outlet to empty and also leaves some volume remaining in the upstanding section of pipe. The water that drains out following flow closure must be replaced with air, invariably including airborne contaminants. Airborne contaminants are then presented with the vacated spout’s large and moist internal surface area, in the dark with plenty available oxygen, and at highly favourable temperatures (between MWT and ambient) for proliferation. Thus, it is the draining down and subsequent available oxygen and large moist surface, rather than the retained water, that causes this problem of retrograde contamination (see also HTM 04-01 Part B para 7.44).
Para 3.51 cont’d: ...Similarly strainers, aerators and flow restrictors should not be used as they become colonised with bacteria.
The outlet fitting of the Optitherm is a largely misunderstood, yet critical, component and it shares no functional aspects with any of the above listed items. It is inherently not a strainer, nor an aerator. The honeycomb structure on its outer surface is designed specifically to retain water in the spout on flow closure, by exploiting the surface tension of the water itself. This diminishes the effect of retrograde contamination, described above. The outlet fitting is also a combined flow regulator and conditioner, two features that specifically retard splashing and aerosol formation. More detail on this fitting is in our ‘Pseudomonad contamination’ blog series.
Para 3.33: Taps should not be aligned to run directly into the drain aperture as contamination from the waste outlet could be mobilised
Para 3.49: Taps discharging directly into a drain hole can cause splashing, which could disperse contaminated droplets. The tap outlet flow should not discharge directly into the waste aperture.
For clinical handwash, the Optitherm thermostatic tap should be paired with an appropriate clinical handwash basin with rear (rather than bottom) waste aperture and no overflow. The Optitherm comes with 3 different ‘spacer’ options that determine the distance between the wall surface and the point of discharge: 170mm, 200mm and 230mm. These allow the Optitherm to be installed with a variety of basin and sluice/sink sizes. Recommended pairings are:
400mm wide Clinical WHB: 170mm, no spacer, Product reference TBT1-170DL
500mm wide Clinical WHB + Small sluice: 200mm, 30mm spacer, Product reference TBT1-200DL
Sluice / surgical sinks: 230mm, 60mm spacer, Product reference TBT1-230DL
Para 3.48: Taps can be lever operated and should be easy to turn off without contaminating the hands.
Recommendations: Hands-free (including lever) operated taps are recommended for clinical wash hand basins.
The Optitherm’s dual levers are unique in that they rotate around a horizontal axis. This offers more comfortable, ergonomic movement, with arms and hands at chest height. Turn on with the short lever, the long lever rotates forward - ready for closure by elbow operation.
With respect to showers, ease of cleaning and maintenance are key points in relation to IPC, (para 3.18).
Construction / Refurbishment - Risks to IPC
An important section of the HBN 00-09 document is its Appendix 3: IPC risk assessment during construction/refurbishment of a healthcare facility.
This is particularly important if remedial or renovation works need to be carried out whilst patients are resident in the healthcare facility. The degree of invasion of the building fabric and also patients’ susceptibility to resultant environmental contaminants determines the infection risk of any particular works project.
Construction Activity Type [A (non-invasive), B, C & D (major demolition & construction)] and the infection Control Risk Group (low, medium, high) are combined to give an overall Risk Class: 1, 2, 3 or 4, each of which has a number of risk measures that need to be followed.
In the case of the Optitherm thermostatic tap and the pre-plumbed shower panels, which are modular, surface mounted and all internal componentry is accessible from the ward-side, construction projects defined as Type B:
Small scale, short duration activities that create minimal dust. Includes:
• access to chase spaces;
• cutting of walls or ceiling where dust migration can be controlled in non-clinical areas.
can be reassigned as Type A:
Inspection and non-invasive activities, includes:
• minor plumbing and activities that do not generate dust or require cutting of walls or access to ceilings other than for visual inspection.
Combined with the IC Risk Group, this means that by installing The Optitherm thermostatic tap, or the TSV1-3 surface mounted shower panel, the potential Risk Class can be reduced from 3 to 2 and 2 to 1; greatly reducing the cost, complexity, duration and recommissioning of the project area, thus minimising the down-time and inconvenience for nursing and medical staff.
Health Building Note 00-10 Performance requirements for building elements used in healthcare facilities (this supersedes HTM 64)
HBN 00-10 Part C (latest edition published in 2013) supersedes Health Technical Memorandum 64: Sanitary Assemblies. It gives guidance to inform the design team of the essential standards of quality and safety that sanitary assemblies must comply with when used in healthcare applications. It assists in the selection, specification and application of sanitary assemblies in healthcare buildings.
In addition to the requirements set by HTM 04-01 and the Water Supply (Water Fittings) Regulations (WRAS Approval), this document also requires that the building design facilitates good infection prevention and control practices and has the quality and design of finishes and fittings that enable thorough access, cleaning, disinfection and maintenance to take place (para 1.17).
It also states (para 1.18) that all finishes in healthcare should be chosen with ease of cleaning in mind, in particular where there is the possibility of contamination by blood or other body fluids.
Horne’s sanitary fittings; surface mounted shower panels and the Optitherm tap are specifically designed for their smooth contours, lack of dirt traps and thus are easily cleaned.
Para 2.8 Exposed surfaces should be smooth and easily cleaned with no sharp edges.
Requirements for shower installations follow:
Para 2.8; a concealed, wall mounted TMV3 approved thermostatic mixing valve should be installed on all showers
Para 2.81: Temperature and volume [flow] controls should be lever operated.
Para 2.82: The shower head should be height adjustable and detachable from its handset.
The above statements describe our most popular healthcare shower T108A2L. In addition it benefits from low level servicing valves and ease of access for maintenance and flushing as required in para 1.17 mentioned above. Localised disinfection of the shower valve and downstream fittings can also be achieved with the T108T42L, which also integrates our ILTDU (In-line thermal disinfection unit).
In some instances, the water supply inlets to the shower panel will come through the wall, for example in a retrofit installation where a ‘concealed’ faceplate shower has been removed, and the connections into the shower panel need to be via flexible stainless steel braided hoses. As per the requirements of this document, these have a fully WRAS approved SOFT-PEX cross-linked polyethylene liner:
Para 2.15: Where flexible hoses are used they must be lined with a suitable alternative to Ethylene Propylene Diene Monomer (EPDM), as well as being WRAS approved.
Taps for clinical sinks, wash-hand basins, scrub troughs and unassisted baths all require wall or bib-mounted taps that are TMV3 approved to the D 08 Standard.
Long lever action and separate hot and cold levers are required on clinical sinks and scrub troughs and a single long lever (for mixed warm water) for Clinical wash-hand basins. Flow straighteners in the outlet should offer minimal restriction (Para 2.21-2, 2.32, 2.39, 2.69-70).
The Optitherm complies with all of these requirements, with the added benefit of the cold water lever at clinical hand wash basins, whereby users can add extra cold water to reach a temperature of their own preference. This also offers continued delivery of (cold) water should the hot water supply fail (the integral TMV is specifically designed to shut off the cold supply in the event of hot water supply failure).
For Bath applications, the Optitherm is available with short levers.
Water Regulations Advisory Scheme (WRAS). Material and Product Approval to the Water Supply (Water Fittings) Regulations 1999 and Scottish Byelaws.
Materials Approval. Non-metallic components such as O-ring seals and other rubber or plastic parts are tested for their effect on water quality, both in terms of leaching compounds and also their ability offer a source of nutrients to support micro-organisms/pathogens (tested according to BS 6920 section 2.4 Growth of aquatic micro-organisms test).
Approval is only given to materials that do not leach compounds and do not support aquatic micro-organisms such as Legionella and Pseudomonas.
Product approval. Is given to complete fittings that undergo mechanical and water quality testing (all non-metallic components must have their own WRAS material approval).
All Horne TMVs, the TSV1-3 shower valve, TBT1 Optitherm thermostatic tap, ILTDU and the Duŝo DS-A60B are fully WRAS approved. Follow the WRAS Approval Search link above to check product approval status.
Severe scalding of patients by washing / bathing water was added to the Department of Health's list of Never Events in 2011 (item 14).
Defined as ‘serious, largely preventable patient safety incidents that should not occur if the available preventative measures have been implemented by healthcare providers’, Never Event incidents have clear potential for causing harm or death but can be avoided by properly implementing the relevant guidance.
Applicable in all NHS Funded settings.
Much of the guidance given in the preceding sections will apply and compliance with these in respect to installation and effective planned maintenance of thermostatic mixing and shower valves should ensure that patients are not at risk of scalding.
In particular, the 2018 Never Event list suggests as guidance:
HBN 00-10 Part C
Managing the risks of hot water and surfaces in health & social care
These documents, also discussed above, are available to download from the adjacent Useful Links list.