Water Treatment and Dialysis Delivery Systems
The treatment train
Water treatment typically includes backflow prevention, a softener, carbon tanks, reverse osmosis (RO), ultraviolet light or ultrafilters, and a distribution loop. The softener removes calcium and magnesium by ion exchange and must be regenerated with brine. Carbon tanks adsorb chlorine, chloramine, and organic contaminants; they are usually arranged in series (worker and polisher). RO removes dissolved ions, bacteria, and endotoxin; monitor conductivity, percent rejection, and pressures. Deionization (DI) is a polishing step with limited capacity, and an exhausted DI bed can release contaminants. Distribution loops must maintain continuous flow and avoid dead legs.
Monitoring and limits
Test for chlorine/chloramine before the first patient and after the carbon tanks per policy; breakthrough means stop dialysis, do not treat, and notify. Conductivity meters and alarms verify dialysate mixing. AAMI standards set chemical and microbiologic limits-for example, product water bacteria <100 CFU/mL and endotoxin <0.25 EU/mL; follow current facility/AAMI limits.
Traps
Carbon is not a softener; RO is not a substitute for carbon; clear water is not necessarily safe. Confusing chlorine with chloramine tests and ignoring a conductivity alarm are common errors.
Rule of thumb: if a water-quality test fails, stop treatment and escalate-never finish the shift on questionable water.