Essentials of water treatment in hemodialysis

Water purity for dialysis is of critical importance for patient health and outcome, and in this regard there are three major points to consider: 1) Hemodialysis (HD) patients are exposed to more than 400 L of water per week. Contrast this with a person with normal kidney drinking only less than 15 L of water per week. 2) The stomach acid and intestinal barrier protect from the ills of contaminated water more effectively than the barrier imposed by the dialyzer membrane. 3) The functioning kidney can further protect the normal individual from the contaminants of water by eliminating these, this protection being absent for the HD patient. Thus the regulations governing the purity of drinking water are further modified by the above considerations: exposure of only 10 to 15 L per week and the efficacy of gut and kidney to protect the individual. Whereas the dialysis water is regulated by more strict purity guidelines, failure in observing any of these guidelines has had disastrous consequences. The use of modern more permeable dialyzer membranes has increased the risk of water contamination, and more stringent purity standards must be strictly followed to avoid harm to the patient. To make water healthier and relatively pure, water authorities often add chemicals such as fluoride, aluminum, chlorine, and chloramines. This makes water unsafe for HD use, because these chemicals have been known to accumulate in dialysis patients leading to significant morbidity and mortality. Thus, aluminum in the dialysis water has caused severe aluminum intoxications often leading to death. Similarly fluoride intoxication has also led to significant clinical catastrophes. Chemicals leaching from water pipes have also led to chemical intoxications; thus, pipes made of lead, copper, or brass zinc are not suitable for delivering water for dialysis.