Convective therapies such as hemofiltration, hemodiafiltration and double high flux dialysis have been shown to improve treatment delivered and treatment tolerance when compared to conventional dialysis therapies. The risk associated with these treatments is primarily in the quality of the substitution fluid. Technological advances now permit on-line produced substitution fluid, thereby significantly reducing the cost associated with hemofiltration and hemodiafiltration. The quality of the substitution fluid is only assured when the quality of the RO water used is within the guidelines set by the Association for the Advancement of Medical Instrumentation (AAMI). Therefore, the success of the application of this therapy is dependent on the water treatment protocols in the dialysis units. The success of this modality as a treatment for chronic renal failure is dependent on identifying those patient groups who will benefit most from this more efficient but more expensive treatment.