ISO 20469:2018

Guidelines for water quality grade classification for water reuse

This document provides guidelines for water quality grade classification to help users determine the suitability and quality of the reclaimed water for safe non-potable reuse applications, based on the level of exposure. The intention is to enable the water quality grade to be identified at the point of use.

Lignes directrices pour la classification de la qualité de l’eau en vue de sa réutilisation

General Information

• Status: Published
• Publication Date: 04-Nov-2018
• ICS: 13.060.01 - Water quality in general
• Technical Committee: ISO/TC 282/SC 3 - Risk and performance evaluation of water reuse systems
• Drafting Committee: ISO/TC 282/SC 3 - Risk and performance evaluation of water reuse systems
• Current Stage: 9093 - International Standard confirmed
• Start Date: 01-May-2024
• Completion Date: 13-Dec-2025

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.

Standards Content (Sample)

INTERNATIONAL ISO
STANDARD 20469
First edition
2018-11
Guidelines for water quality grade
classification for water reuse
Lignes directrices pour la classification de la qualité de l’eau en vue de
sa réutilisation
Reference number
©
ISO 2018
© ISO 2018
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
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ii © ISO 2018 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Water quality grade classification for reuse application . 1
4.1 Water quality grade for reuse application . . 1
4.2 Water quality grade classification . 2
5 Display of water quality grades . 5
Bibliography . 6
Foreword
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bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
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electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www .iso .org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/patents).
Any trade name used in this document is information given for the convenience of users and does not
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expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 282, Water reuse, Subcommittee SC 3,
Risk and performance evaluation of water reuse systems.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
iv © ISO 2018 – All rights reserved

Introduction
The reaffirmation of the importance of water along with food security and energy was a significant
outcome in the actions and the follow-up framework passed at the United Nations Conference on
Sustainable Development (Rio+20). With respect to the management of water resources, essential
actions include the prevention of water contamination, more efficient water usage, and the treatment
and best practices for reuse of wastewater as a water resource by households, industries, and
agriculture, particularly in growing urban areas.
Today, many regions in the world face water shortages, and the feasibility of using reclaimed water to
meet water demands for various purposes is of great interest. On the other hand, the potential health
implications of using reclaimed water is of global concern. This has led to an increasing need to specify
appropriate water quality parameters for specific reclaimed water applications, as well as develop
methods of assessing and managing health risks from both regulatory and application perspectives.
Unless these needs are addressed, opportunities for the development of sustainable and appropriate
reclaimed water applications will be lost.
Health risks associated with the use of reclaimed water occur when users use the reclaimed water
inappropriately without knowing its intended purpose. Therefore, it is important that the reuse
application be clearly identified.
INTERNATIONAL STANDARD ISO 20469:2018(E)
Guidelines for water quality grade classification for
water reuse
1 Scope
This document provides guidelines for water quality grade classification to help users determine the
suitability and quality of the reclaimed water for safe non-potable reuse applications, based on the level
of exposure. The intention is to enable the water quality grade to be identified at the point of use.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 20670, Water reuse —
...