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ISO 26722:2016 – Water Treatment Equipment for Hemodialysis: Technical Requirements and Compliance Guide
Comprehensive overview of the international standard for hemodialysis water treatment systems, covering design, performance, and safety requirements
ISO 26722:2016 establishes performance, safety, and design requirements for water treatment equipment used in hemodialysis and related therapies. Published by the International Organization for Standardization (ISO) and adopted in Canada as CAN CSA ISO 26722-16, this standard is a cornerstone for ensuring reliable production of purified water that meets the stringent chemical and microbiological limits specified in ISO 23500-4. This article provides a technical analysis of the standard’s scope, key requirements, implementation considerations, and compliance pathways for healthcare facilities, manufacturers, and regulatory bodies.
1. Scope and Application
ISO 26722:2016 covers water treatment equipment—from feed water intake to the point-of-use connection to the dialysis machine. This includes systems such as:
- Pretreatment assemblies (sediment filters, softeners, carbon tanks)
- Primary purification units (reverse osmosis, distillation, electrodeionization)
- Post-treatment components (UV disinfection, ultrafilters, storage tanks with recirculation)
- Monitoring and control systems (conductivity, pressure, flow, temperature alarms)
The standard applies to all facilities performing hemodialysis, including hospital-based units, standalone clinics, and home dialysis setups. It does not cover the dialysis machine itself or the dialyzer, nor does it address the final water quality parameters—these are defined in ISO 23500-4 (formerly ISO 13959). However, ISO 26722 requires that the equipment be designed to produce water compliant with those limits under normal operating conditions.
The 2016 revision aligned the standard with modern risk management principles, emphasizing system validation, periodic testing, and documentation requirements. It replaced the earlier ISO 26722:2009 and harmonized terminology with the ISO 23500 family.
Note: In jurisdictions such as Canada, the adoption of ISO 26722 may be mandatory under health authority regulations. Verify local adoption status (e.g., CAN CSA ISO 26722-16) before designing compliance strategies.
2. Technical Requirements
2.1 Design and Materials
The standard mandates that all wetted materials be non-toxic, corrosion-resistant, and capable of withstanding the chemical and thermal conditions of disinfection. Specific requirements include:
- Pipes and fittings: Must be made of materials such as stainless steel 316L, PVC, or cross-linked polyethylene (PEX). Copper and brass are prohibited due to leaching risks.
- Seals and gaskets: Must be compatible with disinfectants (e.g., chlorine, peracetic acid, hot water).
- Tanks: Storage must be designed to prevent stagnation (e.g., conical bottom, continuous recirculation) and fitted with hydrophobic vent filters.
- Valves: Diaphragm valves are preferred; ball valves with threaded ends are not recommended due to potential bacterial harborage.
2.2 Performance Monitoring and Alarms
ISO 26722 requires continuous or periodic monitoring of critical parameters. The system must include alarms and automatic shutdown when parameters exceed limits:
| Parameter | Monitoring Requirement | Alarm / Action Level |
|---|---|---|
| Conductivity / Resistivity | Continuous | Alarm at 10% above set point; auto shut-off if off-spec |
| Pressure (pre- and post-RO) | Continuous | High/low alarm; shutdown for differential pressure deviation >15% |
| Flow rate (product water) | Continuous or at startup | Low flow alarm; automatic bypass if recirculation fails |
| Temperature | Continuous | Alarm and shutdown if temperature exceeds 30°C (or manufacturer limit) |
| UV intensity (if UV used) | Continuous | Alarm when UV dose falls below 40 mJ/cm² (typical) |
All monitors must be calibrated at least annually, with traceable standards. The system must provide an interface for periodic verification by the operator.
2.3 Disinfection and Biofilm Control
The equipment must be designed to allow effective disinfection of the entire water circuit. Acceptable methods include hot water pasteurization (≥85°C for 30 minutes), chemical disinfection (e.g., 2% peracetic acid), or ozone. The standard specifies:
- All components must tolerate the maximum disinfection temperature and chemical concentrations declared by the manufacturer.
- Bypass lines must be flushed during disinfection to ensure no dead legs.
- A documented disinfection schedule must be established based on microbiological risk assessment—typically at least once per month.
Caution: Inadequate disinfection protocols can lead to chronic biofilm formation, which may compromise water quality even if initial limits are met. ISO 26722 emphasizes that validation disinfection cycles are essential for compliance.
3. Implementation Highlights
3.1 Risk Management & Validation
ISO 26722 adopts a risk-based approach. The manufacturer (or the facility team) must perform a formal risk analysis to identify critical control points. The standard references ISO 14971 for risk management. Key implementation steps include:
- Feed water assessment: Conduct quarterly chemical and microbial analysis of the incoming water supply to design appropriate pretreatment.
- System validation: After installation, the system must undergo a 30-day validation period, measuring product water quality daily. The acceptance criteria must meet ISO 23500-4 limits.
- Ongoing verification: Scheduled daily checks (conductivity, pressure, flow) and monthly full microbiological sampling (total viable count, endotoxin).
- Change control: Any modification to the water treatment system (e.g., adding a new filter, changing disinfection method) requires re-validation.
3.2 Documentation and Records
The standard requires a comprehensive documentation system:
- Design specifications: Including piping and instrumentation diagrams (P&IDs), material certifications, and manufacturer’s instructions.
- Operating manual: Detailed procedures for normal operation, disinfection, and troubleshooting.
- Logbook: Daily parameters, disinfection cycles, calibration records, and corrective actions.
- Validation report: Summarizing commissioning data and microbiological validation results.
Best Practice: Use a digital quality management system (QMS) to automate alarms, log data, and generate compliance reports. This simplifies audits and reduces human error.
4. Compliance and Certification Notes
Regulatory compliance with ISO 26722 is assessed through a combination of:
- Self-certification: The manufacturer declares conformity based on internal testing and documented evidence. Many countries accept this as part of CE marking or FDA clearance.
- Third-party testing: For critical public health applications, especially in the US and Canada, independent testing to AAMI/ISO standards may be required by the health authority.
- Periodic audits: Hospital and clinic water systems are often inspected by accreditation bodies (e.g., Joint Commission, DNV GL, CSA). Non-compliance can lead to citation or suspension of services.
Key audit checkpoints include:
- Are the feed water and product water logs complete and within the limits of ISO 23500-4?
- Is the disinfection schedule being followed and effective?
- Are alarms tested monthly?
- Is there a documented procedure for responding to water quality excursions?
Critical: A common deficiency is the absence of a validated endotoxin sampling plan. ISO 26722 mandates that endotoxin levels must be ≤0.25 EU/mL (target) or ≤0.5 EU/mL (action level). Failure to monitor endotoxin can result in immediate shutdown of the dialysis unit.
In summary, ISO 26722:2016 provides the design and operational framework for safe, reliable water treatment in hemodialysis. Medical facilities, equipment manufacturers, and compliance officers must stay abreast of updates and incorporate the standard’s risk management principles into daily practice. Adoption of CAN CSA ISO 26722-16 in Canada further underscores the global harmonization of dialysis water safety standards.
Frequently Asked Questions
Q: How does ISO 26722:2016 relate to the ISO 23500 series?
A: ISO 26722 is part of the broader ISO 23500 family. While ISO 23500-4 sets the water quality limits (chemical and microbiological), ISO 26722 specifies the equipment requirements needed to consistently achieve that quality. ISO 23500-5 covers the dialysis fluid quality, and ISO 23500-3 focuses on the dialysate concentrate. Together, they form a cohesive framework for dialysis fluid safety.
A: ISO 26722 is part of the broader ISO 23500 family. While ISO 23500-4 sets the water quality limits (chemical and microbiological), ISO 26722 specifies the equipment requirements needed to consistently achieve that quality. ISO 23500-5 covers the dialysis fluid quality, and ISO 23500-3 focuses on the dialysate concentrate. Together, they form a cohesive framework for dialysis fluid safety.
Q: Can a facility use the same water treatment system for multiple modalities (e.g., hemodialysis, home dialysis, hemodiafiltration)?
A: Yes, provided the system is designed and validated to meet the most stringent requirements among the therapies used. For instance, hemodiafiltration may require ultrapure water (TVC <0.1 CFU/mL, endotoxin <0.03 EU/mL). The system must be able to consistently deliver that quality at the required flow rate and should include appropriate point-of-use filtration (e.g., ultrafilters). ISO 26722 encourages modular design to accommodate different demands.
A: Yes, provided the system is designed and validated to meet the most stringent requirements among the therapies used. For instance, hemodiafiltration may require ultrapure water (TVC <0.1 CFU/mL, endotoxin <0.03 EU/mL). The system must be able to consistently deliver that quality at the required flow rate and should include appropriate point-of-use filtration (e.g., ultrafilters). ISO 26722 encourages modular design to accommodate different demands.
Q: How often should a water treatment system be validated after initial commissioning?
A: ISO 26722 requires re-validation after any major change (e.g., replacing the RO membrane, altering the piping layout, changing feed water source). Additionally, many health authorities recommend an annual performance verification, including a full microbiological profile over a 5-day period. However, the standard itself does not specify a fixed re-validation interval; it is based on risk assessment and local regulations.
A: ISO 26722 requires re-validation after any major change (e.g., replacing the RO membrane, altering the piping layout, changing feed water source). Additionally, many health authorities recommend an annual performance verification, including a full microbiological profile over a 5-day period. However, the standard itself does not specify a fixed re-validation interval; it is based on risk assessment and local regulations.
Q: What are the documentation requirements if the system is installed in a home dialysis setting?
A: The standard applies equally to home systems with scaled-down documentation. The manufacturer must provide a simplified manual and logbook for the patient or home caregiver. The responsible prescribing physician or clinic must review the logs at least quarterly. However, validation testing and periodic water sampling must still be performed by trained personnel. The standard highlights that home system design must incorporate intuitive alarm signals and automatic lockout to prevent patient misuse.
A: The standard applies equally to home systems with scaled-down documentation. The manufacturer must provide a simplified manual and logbook for the patient or home caregiver. The responsible prescribing physician or clinic must review the logs at least quarterly. However, validation testing and periodic water sampling must still be performed by trained personnel. The standard highlights that home system design must incorporate intuitive alarm signals and automatic lockout to prevent patient misuse.
Article prepared for technical reference purposes. For the official text, refer to the published ISO 26722:2016 or CAN CSA ISO 26722-16. — 2026