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Horne In-Line Thermal Disinfection Unit


For routine thermal disinfection of showers, taps, TMVs, their associated pipe-work feeds, ancillary fittings, mixed water deadleg and terminal outlet fitting using the readily available system temperature hot water supply. Fits to hot and cold supply pipework drops and includes 2 No. 3-way ball valves, connected by four way link mechanism for switch between passive and disinfecting mode. Connections by compression fitting for 15mm copper pipe. Manual operation using bespoke key with safety warning (supplied separately).  

Part Number: ILTDU

Designed and manufactured by Horne Engineering Ltd. Patented worldwide.

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Why use the ILTDU?

Disinfection: the reduction of the number of pathogenic micro-organisms to safe levels.

Via the incoming water supply and by retrograde contamination, Psuedomonas, Legionellae, Mycobacteria and other pathogens can colonise the last two metres of domestic water supply (DWS) pipework, including the outlet fitting (any TMV, tap or shower). This problem is specifically described in Health Technical Memorandum (HTM) 04-01, Part C.  Various approaches to solving this problem have proven costly and ineffectual.

Proven Solution
Our In-Line Thermal Disinfection Unit (ILTDU) facilitates periodic high temperature thermal disinfection using the readily available hot water supply. Now the thermal regime can be extended to the point of water discharge: therefore, the wetted surfaces of all downstream components, including the mixing valve and the outlet fitting, can be raised to system temperature.

The narrated animation above provides further information about the ILDTU: explaining how it works, outlines safety considerations and also includes thermal imaging camera footage of the Optitherm tap fed via an ILTDU in disinfection mode.

Combine the disinfection process with pipework flushing at an elevated velocity using a Flushing Kit.  This serves to shear excess biofilm from the internal pipe surfaces and remove it to drain, thus improving water quality and reducing the contamination risk. For further operational advice for  successful resetting of retrograde contaminants to zero read our Thermal Disinfection - Top Tips blog.

Hospital Trials
Results of early hospital trials have proven the ILTDU to be highly effective in reducing Pseudomonas cfu counts to zero following a single treatment and replacing the need for POU filters and last-resort wash-station replacement. Check out our Case Studies: Sustainable Water Hygiene and ILTDU gives Eureka Moment.

Shower Panel Integration
Horne TSV1 shower panels are now available with the ILTDU built-in and are supplied with an adapted Pipe Cover (with access slot for key operation) available in 465mm (T4 variant) or 940mm lengths (T9 variant). 


The In-Line Thermal Disinfection Unit is a patented Horne design


  • The ILTDU is UK Water Regulation 4 Approved (materials approval), KIWA certificate 2002725
  • All HORNE products are manufactured under our Quality Management System to BS EN ISO 9001:2015. Certificate No. FM 01224

Useful Documents

Related Products

Recent Installations

  • Aconbury Hospital
  • Barnsley Hospital
  • Bupa Cromwell Hospital
  • Guy's & St Thomas' NHS FT
  • Homerton Hospital
  • Imperial College Healthcare Trust
  • Kings College Hospital
  • Northern General Hospital, Sheffield
  • Northwick Park & St. Marks Hospital
  • Nottingham University Hospitals
  • Pilgrim Hospital
  • Princess Anne Hospital
  • Redditch Town Hall
  • Royal Bournemouth Hospital
  • Royal Brompton Hospital
  • Royal Free Hospital
  • Southampton University Hospitals
  • Southend Hospital
  • The London Clinic
  • University Hospitals, Plymouth
  • Walton Hospital, Chesterfield
  • Warwick Hospital
  • West Suffolk Hospital
  • Whittington Hospital
Horne 15 TMV supplying blended water to lever taps. Thermal disinfection facility via upstream ILTDU, In-line Thermal Disinfection Unit

Case Study: Sustainable Water Hygiene

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