The EN ISO 15883 series, jointly developed under the Vienna agreement by ISO/TC 198 and CEN/TC 102, describes the design and functionality of washer-disinfectors (WD), used to disinfect medical tools. Part 1 of the series specifies general design requirements, process specifications and validation methods for all kinds of washer-disinfectors. The subsequent parts focus on the design of particular devices, processing special load including particular specifications of the processing process, such as requirements for the thermal processing of surgical instruments or the chemo-thermal processing of flexible endoscopes.