ISO 20426:2018

Overview

ISO 20426:2018 - Guidelines for health risk assessment and management for non-potable water reuse provides technical guidance to assess and manage health risks from pathogens in reclaimed water. Applicable to reclaimed water produced from any source (raw sanitary sewage, treated municipal wastewater, industrial wastewater, stormwater potentially influenced by sewage), this standard focuses on non-potable water reuse and offers a structured framework to reduce health risks associated with production, storage, transport and end-use of reclaimed water. The approach can also be applied to chemical contaminants where relevant.

Key topics and technical requirements

ISO 20426:2018 structures health risk management around a clear, practical framework and includes the following technical topics:

• Risk assessment and management framework - Establishes how to estimate and reduce risks to acceptable societal/local levels.
• Hazard identification - Identification of pathogens and hazardous events, exposure routes and exposure at end-use.
• Risk assessment methods - Guidance on both qualitative and quantitative health risk assessment (QHRA), including recognition of limitations and uncertainties.
• Risk control measures - Hierarchy of controls: source control, treatment barriers, and end-use controls.
• Treatment performance and monitoring - Selection of treatment barriers, monitoring methods, performance control points (PCPs) and reclaimed water quality monitoring.
• Monitoring and QA/QC - Recommendations for compliance and performance monitoring, and quality assurance/quality control procedures.
• Annexes - Informative annexes provide practical material (common pathogens in wastewater, QHRA examples, PCP examples, and example monitoring parameters).

Practical applications and intended users

ISO 20426:2018 is designed for organizations involved in water reuse planning, implementation and regulation. Typical users include:

• Water and wastewater utilities and treatment plant operators
• Public health agencies and regulators developing reuse policies and permits
• Engineering and consulting firms designing reclamation systems and monitoring programs
• Agricultural managers, landscape and irrigation planners using reclaimed water for non-potable applications
• Industrial facility managers using reclaimed water for cooling, process water or dust control

Practical uses include establishing treatment performance goals, designing multi-barrier treatment trains, defining PCPs and monitoring plans, conducting QHRA for specific end-uses (e.g., irrigation, urban reuse, recreation), and integrating risk management into operational systems.

Related standards

• ISO 20670 (Water reuse - Terminology) - normative reference
• ISO 16075 series - guidance for irrigation with reclaimed water (referenced for agricultural uses)
• Management integration: ISO 9001 (quality systems) and ISO 31000 (risk management) are noted as complementary frameworks.

Keywords: ISO 20426:2018, non-potable water reuse, health risk assessment, reclaimed water, pathogens, risk management, performance control points, water reuse guidelines.