Water quality – how to ensure a pure supply

All modern hospitals depend on decontamination centres for the cleaning and disinfection of medical equipment to extremely high and consistent standards. To meet such stringent standards, these centres all depend, in turn, on a consistent supply of high quality purified water to carry out decontamination tasks. Water plays a pivotal role in many areas of decontamination, and has to be available in large volumes at specified levels of purity. One use of purified water in particular is for the final rinse in automated washer-disinfectors, to remove any remaining contaminants or residual chemistries left over from the previous cleaning stages. It is therefore vitally important that the water used at this stage of the cleaning cycle does not re-infect or leave mineral deposits that could harbour potentially harmful bacteria or endotoxins; hence the stringent microbiological specification set by the HTM guidelines. For autoclaves the requirement is somewhat different, in that the water is not used for rinsing, but raised as steam for sterilisation. However, with washerdisinfectors, this final process must not result in instruments being left with unwanted surface contaminants.

Long-established guidelines

Guidelines covering the standards of water purity that decontamination centres should meet have been in existence for over a decade, and were originally covered by several HTM guideline documents published by NHS Estates, such as HTM 2030, which covered all aspects of the operation and maintenance of washerdisinfectors; HTM 2031 (“Clean steam for sterilisation”), which dealt with steam generators and provided guidelines for both steam purity and feedwater quality, and HTM 2010 (“Sterilisation”). These have now been combined into the HTM 01 series on decontamination, itself further sub-divided into seven key areas, one of which, HTM 01-01, titled “Decontamination of reusable medical devices”, relates to the management, operation and validation of washerdisinfectors and endoscope reprocessors. Part A, Management and Environment, of HTM 01-01, has been released, but Part B, “Equipment”, has yet to be finalised and released. Within Part B are the details of the revised water quality requirements. Additionally, there is a European standard, prEN ISO 15883, for washerdisinfectors, which is broadly similar to the original HTM 2030 C30/C32 that sets out the quality of water to be used at various stages of the decontamination process.