I would go to Distilled Water for Kidney Failure, Get him to drink a Gallon a day. No Less, and more would actually work better. Distilled Water is what must be used to perform Kidney Dialysis. Big Pharma knows this... Kidneys are clogged and have been slowly dying off for years thus failing, this is Kidney Failure. Supplementation with Borax likely wouldn't have any deleterious effects.