Water supply aluminium concentration, dialysis dementia, and effect of reverse-osmosis water treatment.

Dialysis dementia appeared in 18 of 258 patients treated by haemodialysis. All Cases developed in patients treated by home dialysis (150) and none in patients treated exclusively by hospital dialysis (108). Analyses of the domestic water supply for each month on dialysis showed that dementia occurred only in those whose water supply had a high aluminium concentration (greater than 80 micrograms/l). The significant exponential relation (p less than 0.01) between the mean aluminium concentration in the water used to prepare the dialysate and the time taken to death from dementia indicates that there is probably no safe aluminium concentration and that removal of aluminium from water is essential before haemodialysis, particularly in areas where alum is used in water treatment as a clarifying agent. Reverse osmosis treatment satisfactorily removes aluminium and many other substances from water. Its application had a beneficial effect on 7 of 9 patients previously exposed to dialysate prepared from water with a high aluminium content and prevented the appearance of dementia in 24 patients whose water was so treated from the start of haemodialysis.