An automated machine designed to clean, decontaminate, and thermally disinfect reusable invasive medical devices (RIMD) used in dentistry such as dental instruments. There are a number of automated stages including pre-rinsing, cleaning, interim rinsing, thermal disinfection, final rinsing, and drying. Disinfection is achieved by flushing with water at 90°C (194°F) for 1–10 minutes. The machine is unsuitable for heat-sensitive items. The specification of the washer-disinfector should comply with requirements of EN ISO 15883, parts 1 & 2. Each washer-disinfector should be fitted with an independent process monitoring system in accordance with EN ISO 15883 part 1. When lumened devices, such as dental handpieces, are being reprocessed, the washer-disinfector should be provided with load carriers that permit the irrigation of the lumened device. Washer-disinfectors and accessories should be specified, installed, validated, commissioned, tested, and operated in accordance with EN ISO 15883, parts 1,2 & 5 or UK standard HTM 01–05. Washer-disinfectors should be subject to planned preventative maintenance.