Water quality for on-line haemodiafiltration.

The term 'ultrapure water' is a common way to define water used for on-line treatments: it refers to the absence of chemical, organic and microbiological contamination. To be more accurate in definition, every known and potential contaminant has to be fixed at its limit value. AAMI recommendations and various Pharmacopoeias have set limits for dialysate based on traditional dialysis treatments, but on-line treatments should also be regulated by guidelines for infusion solutions. Modern water treatment technology allows us to obtain a proper chemical quality both for dialysate and infusion solutions in on-line dialysis. Technology alone, however, cannot guarantee adequate microbiological quality if water treatment is not linked to the appropriate maintenance, monitoring, cleaning and sanitizing procedures. On-line dialysis treatments, as well as high-flux dialysis, use the monitor as an on-site pharmaceutical factory where sterilization by filtration forces nephrologists to look for procedures to keep sterile water sterile.