In-line Thermal Disinfection Unit (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 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 the Addendum to Health Technical Memorandum 04-01.

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.

Results of initial 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. Read our case study from St Richard's Hospital in Chichester here.

Horne TSV1 shower panels are now available with an integral ILTDU and adapted Pipe Cover (with access slot for key operation) available in 465mm (T4 variant) or 940mm lengths (T9 variant).  For more information, look for the T4 and T9 Quick Code options via the shower selection pages.

Part Numbers
In-line Thermal Disinfection Unit:  ILTDU
Operating Key:  6236

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

WRAS Approval
The ILTDU has been granted WRAS Approval: Approval Number 1511330 (certificate below)

How to Specify
Please copy and paste the statement below into your specification document:

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 by 15mm copper pipe. Manual operation using bespoke key with safety warning (supplied separately).

Manufactured and supplied by Horne Engineering Ltd, PO Box 7, Rankine Street, Johnstone, PA5 8BD. Tel: +44 (0)1505 321455, Fax: +44 (0)1505 336287, email: 

 Recent Installations

  • Barnsley Hospital
  • Basildon Hospital
  • Calderdale Royal Infirmary
  • Cambridge University
  • Chelsea Football Club
  • Derriford Hospital, Plymouth
  • Ealing Hospital
  • Forest Lodge MH, Sheffield HSC
  • Frinton & Walton Swimming Pool
  • Garret Anderson Centre, Ipswich Hospital
  • Huddersfield Royal Infirmary
  • Kings College Hospital
  • Kingston Hospital
  • Leeds Teaching Hospitals
  • Leicester General Hospital
  • New Cross Hospital
  • Northwick Park Hospital
  • Monklands Hospital, NHS Lanarkshire
  • Peppermill Court CUE
  • Pilgrm Hospital, Lincolnshire
  • Princess Royal University Hospital
  • Royal Bournemouth Hospital
  • Royal Marsden Hospital
  • St George's Hospital, Tooting
  • St Helier Hospital
  • St James's University Hospital, Leeds
  • St Marks Hospital
  • St Richard's Hospital, Chichester
  • The London Clinic
  • Watford General Hospital
  • Wexham Park Hospital

Useful Documents

In-line Thermal Disinfection Unit
ILTDU at St Richard's Hospital
PDF1741 KB
ILTDU - Managing Water Safety
PDF4870 KB
ZIP3412 KB
ILTDU Dimensions - DWG Document
Drawing File435 KB
ILTDU Dimensions - PDF Document
ILTDU Capacity Chart
ILTDU Instructions
ILTDU with Pipe Cover Instructions
ILTDU In-service Record Sheet
WRAS Certificate - ILTDU