Dialysis relies upon the transfer of waste products and electrolytes across a semi-permeable membrane contained in the dialyser facilitated by the dialysis fluid, a fast-flowing electrolyte solution prepared continuously by the mixing of treated water with a concentrated electrolyte solution. Both the water, the buffer and electrolyte composition play important roles in modulating complications associated with treatment. With respect to water, historically the focus was on chemical contaminant content, but more recently has shifted to microbiological quality due to the role that such quality plays in the pro-inflammatory state. The composition of the dialysis fluid is crucial in normalization of electrolyte composition of plasma water, homeostasis and acid-base balance, and should be individualized to the patients’ requirements in the same way as blood and dialysate flow rates are individualized to ensure optimal comfort and minimal complications associated with the procedure.