ISO 20469:2018

Overview - ISO 20469:2018 (water quality grade classification for water reuse)

ISO 20469:2018 provides guidelines for classifying reclaimed water quality to support safe non‑potable water reuse. The standard groups reclaimed water into three quality grades (High, Medium, Fair) based on the likely level of human exposure and intended application. Its purpose is to enable a clear, point‑of‑use identification of water quality and related precautions so users can safely and appropriately employ reclaimed water.

Key topics and requirements

• Three water quality grades:
  • High - suitable where direct public access and/or body contact is likely (examples: toilet flushing, playground irrigation, landscape water features). Minimum examples of treatment: secondary treatment with filtration and disinfection.
  • Medium - suitable for scenarios with limited or incidental body contact (examples: restricted urban irrigation, agricultural irrigation of processed food crops). Minimum examples of treatment: secondary treatment and disinfection.
  • Fair - for uses without potential for public access or body contact (examples: landscape irrigation without public access, industrial/energy crop irrigation). Minimum examples of treatment: secondary treatment (high‑rate clarification with coagulation/flocculation or stabilization ponds).
• Point‑of‑use display: grades must be clearly displayed where the reclaimed water is used, including application type and precautions (e.g., “Not drinking water”, “No swimming”, “Do not trespass”).
• Local determination: jurisdictions, regulators or authorities determine appropriate grade assignments and prohibited uses based on local health risk assessment.
• Complementary information recommended for displays: source water type, treatment type, prohibited uses, notifications for exposed persons, and commonly used symbols.

Practical applications and who uses this standard

ISO 20469 is intended for organizations involved in planning, operating and regulating non‑potable water reuse:

• Municipal water and wastewater utilities
• Urban planners and landscape architects
• Irrigation project designers and agricultural managers
• Industrial facilities using reclaimed water for cooling or processes
• Public health authorities and regulators
• System operators and facility managers responsible for signage and end‑use controls

Use cases include deciding minimum treatment needs for reclaimed water, designing labeling/signage at points of use, and integrating water quality grades into reuse permits, risk assessments, and public outreach.

Related standards

ISO 20469 references and aligns with other ISO guidance for water reuse and health risk:

• ISO 20670 (vocabulary)
• ISO 16075‑1/2/3/4 (treated wastewater use for irrigation projects)
• ISO 20426 (health risk assessment and management for non‑potable reuse)
• ISO 20468‑1 (performance evaluation of treatment technologies)
• ISO 20760‑1/2 and ISO 20761 (urban water reuse guidelines and safety evaluation)

Keywords: ISO 20469, water reuse, reclaimed water, water quality grade, non‑potable reuse, wastewater reuse, water quality classification, public health protection.