What are the guidelines for using reverse osmosis (RO) water in hemodialysis treatments?

Reverse Osmosis (RO) in Hemodialysis: Water Treatment Standards

Dialysis water must comply with strict chemical and microbiological standards, requiring a double-pass reverse osmosis (RO) system as the gold standard for water purification in hemodialysis. 1, 2

Essential Water Treatment System Components

An optimal water treatment system for hemodialysis requires:

• Tap water pretreatment followed by double-pass reverse osmosis (DRO) rather than single-pass systems 1, 2, 3
• Every component from treatment through delivery to dialysis machines must prevent chemical and microbiological contamination 1
• The system should achieve RO efficiency with water rejection rates below 30% (modern systems have improved from historical 70% rejection rates) 4

Water Quality Standards

Chemical Quality Requirements

Treated water must meet European Pharmacopoeia limits at both the water treatment inlet and RO outlet 2. The dialysate, concentrate, and infusion fluids require separate compliance with specific Pharmacopoeia standards.

Microbiological Quality Standards

Target "ultra-pure" dialysate as standard practice:

• Microbial count: <0.1 CFU/mL
• Endotoxins: <0.03 U/mL 2

These standards align with AAMI (Association for the Advancement of Medical Instrumentation) requirements for dialysis water safety 5, 6. The dialysis fluids must meet the same safety standards as intravenous medications 1.

Critical Maintenance Protocols

Regular Disinfection

• Daily overnight automatic thermal disinfection of distribution piping represents best practice 3
• Regular disinfection of dialysis machines greatly enhances microbiological purity 2
• Preventive and frequent disinfection is more effective than reactive sampling 7

Material Selection

Progressive optimization requires:

• Eliminate polyvinyl chloride (PVC) from the system
• Use stainless steel and/or cross-linked polyethylene thermoplastic polymer for distribution systems 3

This material upgrade, combined with DRO, reduced contamination from 247.4 ± 393.7 CFU/mL to 2.8 ± 3.2 CFU/mL in one 16-year study 3.

Monitoring Requirements

Implement standardized microbiological testing methods rather than relying on variable laboratory techniques that may underestimate contamination 7. Regular chemical and microbiological testing with periodic system revalidation is mandatory 1, 2.

Sampling Points

Monitor water quality at multiple locations:

• Product water (highest contamination risk) 8
• Storage water
• Middle port water
• Return water 8

Common Pitfalls and Prevention

Acinetobacter species represent the most common contaminant in dialysis water systems 8. Product water shows the highest microbial presence and requires the most vigilant monitoring.

Inadequate water purification has caused documented patient injuries and deaths 6, making this a critical patient safety issue rather than merely a technical concern.

For Online Hemodiafiltration

When producing substitution fluid online, even more sensitive microbiological verification methods are required due to direct fluid contact with blood 7.

Physician Responsibilities

The physician in charge must establish a multidisciplinary team to evaluate local chemical hazards and institute appropriate additional controls beyond standard requirements 2. Dialysis water should be viewed as a medicinal product requiring the same quality assurance as any intravenous medication 3.

Home Dialysis Considerations

Home dialysis water must comply with identical chemical and bacteriological quality standards as in-center dialysis 2, requiring the same RO treatment systems and monitoring protocols.