ISO 20760-1

ISO/FDIS 20760-1:2025(en)
Second edition
2025-06-19
ISO/TC 282/SC 2
Secretariat: SAC
Date: 2025-08-12
Water reuse in urban areas — Guidelines for centralized water reuse
system —
Part 1:
Design principle of a centralized water reuse system
Réutilisation de l'eau en milieu urbain - — Lignes directrices concernant les systèmes centralisés de
réutilisation de l'eau —
Partie 1: Principe de conception d'un système centralisé de réutilisation de l'eau
FDIS stage
ISO/FDIS 20760-1:2024(E2025(en)
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ii
ISO/FDIS 20760-1:2025(en)
Contents
Foreword . iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Abbreviated terms . 2
5 Planning and design of a centralized water reuse system . 3
5.1 General . 3
5.2 Estimation of water demand . 3
5.3 Site conditions . 4
5.4 System components . 5
5.5 Possible models of the system . 5
5.6 Basic principles . 8
6 Source water considerations . 8
6.1 Type of source water . 8
6.2 Water quality considerations for source water . 10
6.3 Reliability considerations . 10
6.4 Economic considerations . 11
7 Reclaimed water treatment system . 11
7.1 General . 11
7.2 Centralized water reuse treatment system design principles. 12
7.3 Possible centralized water reuse treatment system configurations . 13
7.4 Treatment processes . 14
8 Reclaimed water storage system . 14
8.1 General . 14
8.2 Storage types . 14
8.3 Storage considerations . 15
8.4 Size of the storage facility and turnover considerations . 16
8.5 Control of water quality . 16
8.6 Specific considerations for open storage reservoirs . 17
9 Reclaimed water transmission and distribution system . 17
9.1 General . 17
9.2 Components and models of the distribution system . 18
9.3 Pumping stations . 19
9.4 Reclaimed water distribution systems . 20
10 Monitoring system . 21
10.1 General . 21
10.2 Monitoring locations and facilities . 21
10.3 Monitoring of source water . 21
10.4 Monitoring and control of treatment facilities . 22
10.5 Monitoring of distribution system . 22
10.6 Monitoring of storage . 22
10.7 Monitoring of end-user sites . 22
11 Emergency response plan . 22
Bibliography . 24

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ISO/FDIS 20760-1:2024(E2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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 committee has been
established has the right to be represented on that committee. International organizations, governmental and
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International Electrotechnical Commission (IEC) on all matters of 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent rights
in respect thereof. As of the date of publication of this document, ISO had not received notice of (a) patent(s)
which may be required to implement this document. However, implementers are cautioned that this may not
represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation onof the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO'sISO’s adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT)), see
www.iso.org/iso/foreword.htmlthe following URL: .
This document was prepared by Technical Committee ISO/TC 282, Water reuse, Subcommittee SC 2, Water
reuse in urban areas.
This second edition cancels and replaces the first edition (ISO 20760-1:2018), which has been technically
revised.
The main changes are as follows:
— — addingadded information regarding the stability evaluation and corresponding evaluation
parameters;
— — addingadded information regarding the performance evaluation of typical treatment processes.
A list of all parts in the ISO 20760 series can be found on the ISO website.
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/FDIS 20760-1:2025(en)
Introduction
With economic development, climate change and increases in population and rapid urbanization, water has
become a strategic resource especially in arid and semi-arid regions. Water shortages are considered as one
of the most serious threats to sustainable development of society. To address these shortages, reclaimed water
is increasingly being used to satisfy water demands and this strategy has proven useful in increasing the
reliability of long-term water supplies in many water-scarce areas.
The role of water reuse is growing for urban areas in many countries including landscape irrigation, industrial
uses, toilet and urinal flushing, firefighting and fire suppression, street cleaning, environmental and
recreational uses (ornamental water features, water bodies’ replenishment, etc.) and vehicle washing. These
centralized water reuse systems have been developed to the degree that they are now considered as an
effective component of urban water management and are used in many cities and countries.
The essential components of a reclaimed water treatment system include a water source (s),sources,
wastewater collection systems (sewers and pumping stations), a wastewater treatment facility, a reclaimed
water distribution system, reclaimed water storage, a water quality monitoring system and operation and
maintenance provided by experienced and certified operators. The variable nature and diversity in source
water present a challenge to ensuring water safety and reliability in each system component. A further
complication to distributing the reclaimed water is that different water reuse applications can have different
levels of water quality, which would consider more complex water use patterns and system models.
This document provides design principles for centralized water reuse systems in urban areas. It considers and
addresses the critical issues and factors in the design of the different system components and is intended to
assist water engineers, authorities, decision-makers and stakeholders in considering feasible and cost-
effective approaches for safe and reliable fit-for-purpose water reuse. For details on the management of a
centralized water reuse system, see ISO 20760-2. Additionally, for details on the design principles of
decentralized or onsite water reuse systems in urban areas, see ISO 23056.
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DRAFT International Standard ISO/FDIS 20760-1:2025(en)

Water reuse in urban areas — Guidelines for centralized water reuse
system —
Part I: 1:
Design principle of a centralized water reuse system
1 Scope
This document provides guidelines for the planning and design of centralized water reuse systems and water
reuse applications in urban areas.
This document addresses centralized water reuse systems in their entirety and is applicable to any water
reclamation system component (e.g. source water, treatment, storage, distribution, operation and
maintenance and monitoring).
This document provides:
— — system components and possible models of a centralized water reuse system;
— — design principles of a centralized water reuse system;
— — common assessment criteria and related examples of water quality indicators, all without setting any
target values or thresholds;
— — specific aspects for consideration and emergency response.
This document e
...