ISO 23500:2011 provides dialysis practitioners with guidance on the preparation of dialysis fluid for haemodialysis and related therapies and substitution fluid for use in online therapies, such as haemodiafiltration and haemofiltration. As such, ISO 23500:2011 functions as a recommended practice.ISO 23500:2011 addresses the user's responsibility for the dialysis fluid once the equipment used in its preparation has been delivered and installed. For the purposes of ISO 23500:2011, the dialysis fluid includes water used for the preparation of dialysis fluid and substitution fluid, water used for the preparation of concentrates at the user's facility, as well as concentrates and the final dialysis fluid and substitution fluid.Excluded from the scope of ISO 23500:2011 are sorbent-based dialysis fluid regeneration systems that regenerate and recirculate small volumes of dialysis fluid, systems for continuous renal replacement therapy that use prepackaged solutions, and systems and solutions for peritoneal dialysis.