The text of ISO 13959:2014 has been prepared by Technical Committee ISO/TC 150 "Implants for surgery" of the International Organization for Standardization (ISO) and adopted as EN ISO 13959:2015 by Technical Committee CEN/TC 205 "Non-active medical devices", the secretariat of which is held by DIN (Germany). The responsible German committee is Working Committee NA 063-01-03 AA "Extrakorporaler Kreislauf, Apparate und Einmalartikel" ("Extracorporeal circuits, equipment and disposables") at DIN Standards Committee Medicine (NAMed). This document specifies minimum requirements for water to be used in haemodialysis and related therapies. It includes water to be used in the preparation of concentrates, dialysis fluids for haemodialysis, haemodiafiltration and haemofiltration, and for the reprocessing of haemodialysers. The operation of water treatment equipment and the final mixing of treated water with concentrates to produce dialysis fluid are excluded from this document. Those operations are the sole responsibility of dialysis professionals. This document does not apply to dialysis fluid regenerating systems.