Valve Sizing Tool

Thermal Disinfection - Top Tips

Top Tips for effective, reliable, and repeatable results.

Thermal disinfection of water system terminal fittings in hospital settings has proven crucial for effectively controlling waterborne and retrograde bacterial contamination. The patented Horne In-line Thermal Disinfection Unit was designed specifically for this purpose and has proven a game-changer for resetting contamination counts to zero.

New customers attempting to use the product, however, may not always achieve these anticipated results first time. Here, our technical team are on hand to assist; to understand every step of the process and, where procedural actions have perhaps deviated from our recommended best practice, advise on remedial action or offer explanations or alternative solutions for facilitating optimal techniques and outcomes.

As a result of various discussions, we've compiled a list of our top tips to help you safely achieve effective, reliable, and repeatable thermal disinfection.  Reset Pseudomonas Aeruginosa counts to zero with every thermal treatment.

  • Use Appropriate PPE and Equipment for the Task
    Consider the elevated temperature of the discharge water and take appropriate safety actions to prevent scalding of operatives, and nearby staff and patients. Cordon the area from staff and patients. Wear appropriate PPE and carefully consider tools and equipment, and their handling and laying down (risk of contamination) for safely and hygienically discharging the hot water from tap or shower head to drain.
  • Include All Components in Disinfection   
    Always include the shower handset, hose, and any other associated component in the disinfection process. Removing a handset and then replacing it after thermal disinfection undermines the whole process. If a filter handset is in use, consider replacing it with a new standard, non-filtering handset. Filtering handsets accumulate bacteria on the upstream side of the internal filter and, following disinfection, the remaining (albeit dead) bacteria held by the filter provide an easy nutrient source for planktonic bacteria and dispersed biofilm clumps arriving from upstream. Therefore, the re-establishment of contamination can be greatly accelerated.
  • Ensure Full Immersion of the Outlet
    Ensure the tap or shower outlet fitting is fully immersed in the flow of hot water. Wastage of excess high temperature water during the disinfection process may be reduced by throttling to an optimum flow rate that reduces the volume discharged whilst maintaining contact with the entire surface of the outlet or jets.
  • Maintain Correct Temperature and Duration
    Ensure the water temperature reaches a minimum of 60°C, then run for no less than 10 minutes for an effective 6 log reduction in bacteria numbers (see temperature tolerance graph* in adjacent image carousel). Use a good quality calibrated digital thermometer, with probe tip in the water flow, to accurately monitor the temperature.  If the hot water supplying the fitting cannot reach 60°C, the effectiveness of this disinfection method may be diminished. The temperature tolerance graph illustrates that reducing the disinfection temperature, even slightly, to 55°C increases the required minimum disinfection duration to 35 minutes to achieve a similar 6 log reduction in bacteria numbers.
  • Minimise Aerosolization of the Drain Contents
    Make sure to aim the discharge hose onto the floor (or basin surface) adjacent to rather than directly into the drain aperture. This will reduce disturbance and aerosolization of the drain contents and reduce the potential for additional retrograde contamination of the treated and other local outlets.
  • Utilize Effective Flushing Techniques 
    Alongside thermal disinfection, implement elevated velocity (EV) flushing to effectively remove excess pipework biofilm and contaminants. 95% of a water system’s bacterial load is held in biofilms† attached to pipework internal surfaces. Recognise EVF is not the same as a Duty Flush, and it’s the change in flow equilibrium that increases shear forces at the pipe walls, destabilising and scouring the excess biofilm away.
  • Sustained Elevated Velocity Flushing 
    Ensure that elevated velocity flushing is sustained for a sufficient duration to properly remove biofilms. The bulk of the contamination / biofilm accumulation may be some distance upstream, thus take time to discharge at the outlet. The video in our earlier blog Biofilm removal by shear velocity illustrates this potential delay. If the drain struggles to cope with the increased water volume, consider using a large container or water butt, with tap at its base, to contain the excess volume, whilst managing the flow toward the drain.  A standard size bucket to catch the excess flow will probably be inadequate; filling too quickly to allow flow velocity to reach maximum, and undermining the mechanical shearing effect.
  • Record the Tasks
    Maintain comprehensive records of the flushing and thermal disinfection processes. Log the outlet location (or identity), thermal disinfection temperature and duration, and EV flushing duration and observations. Collect and record water sample results initially to verify the reset of pathogen counts to zero.
  • Prepare Training Materials and Method Protocols
    Provide thorough training for all staff involved in disinfection procedures. Ensure complete understanding of the risks and benefits is embedded across the team. Develop and implement detailed risk assessment and method statements (RAMS) to ensure consistent and effective practices, even after team personnel changes.
  • Consider Planned Preventative Treatment to Minimise Risks and Cost
    Conduct regular EV Flushing with Thermal Disinfection to knock back biofilm build-up and reset opportunistic pathogen counts to zero. Once proven that the method and protocol (mind these Top Tips!) works every time, then additional efficiencies can be achieved; reduce water sampling collection and analysis costs and save precious FM time.

By following these top tips, you can achieve repeatable, successful thermal disinfection, easily manage a known reservoir of infection - waterborne and retrograde contamination, and ensure a safer environment for patients and staff in hospital settings.

* Annotated. From Spinks et al, Thermal inactivation of water-borne pathogenic and indicator bacteria at sub-boiling temperatures.  Water Research 40 (2006), 1326-32.

† Source: Professor Hans Kurt Fleming, Biofilm Institute.