ISO/TS 24522:2019

Event detection process: Guidelines for water and wastewater utilities

This document provides guidance for water utilities on the detection and classification of water and wastewater events. The following subjects are within the scope of this document: — publicly and privately owned and operated water utilities. It does not favour any particular ownership or operating model; — all aspects of the drinking water system and the wastewater system; — all causes of abnormal changes in water and/or wastewater service provision capable of detection by monitoring systems including accidents, unexpected operational changes, natural hazards and intentional disruption. This document is independent of the measurement methods used to collect the data. The document focuses on events which could imminently affect the water utility's interested parties. The following are outside the scope of this document: — methods of design and construction of drinking water and wastewater systems; — plumbing and drainage systems not under the control of the water utility. This document does not include details about action taken as a result of event detection. For such details see ISO 24518 and EN 15975 Part 1.

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General Information

• Status: Published
• Publication Date: 26-Feb-2019
• ICS: 03.080.30 - Services for consumers
• ICS: 13.060.20 - Drinking water
• ICS: 13.060.30 - Sewage water
• Technical Committee: ISO/TC 224 - Drinking water, wastewater and stormwater systems and services
• Drafting Committee: ISO/TC 224 - Drinking water, wastewater and stormwater systems and services
• Current Stage: 9093 - International Standard confirmed
• Completion Date: 29-Jun-2022

Standards Content (Sample)

TECHNICAL ISO/TS
SPECIFICATION 24522
First edition
2019-02
Event detection process: Guidelines
for water and wastewater utilities
Reference number
ISO/TS 24522:2019(E)
ISO 2019
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ISO/TS 24522:2019(E)
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© ISO 2019

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ISO/TS 24522:2019(E)
Contents Page

Foreword ..........................................................................................................................................................................................................................................v

Introduction ................................................................................................................................................................................................................................vi

1 Scope ................................................................................................................................................................................................................................. 1

2 Normative references ...................................................................................................................................................................................... 1

3 Terms and definitions ..................................................................................................................................................................................... 1

4 Principles of an event detection process ................................................................................................................................... 5

4.1 Design phase ............................................................................................................................................................................................. 5

4.1.1 General...................................................................................................................................................................................... 5

4.1.2 Influence matrix table and EDP .......................................................................................................................... 6

4.1.3 EDP inputs ............................................................................................................................................................................. 7

4.1.4 EDP design ............................................................................................................................................................................ 7

4.1.5 EDP target service level design ........................................................................................................................... 8

4.2 Detection phase ...................................................................................................................................................................................... 8

4.2.1 General...................................................................................................................................................................................... 8

4.2.2 Validation process .................. .................................................... ..................................................................................... 8

4.2.3 Further event monitoring ........................................................................................................................................ 9

4.3 Ongoing activities ................................................................................................................................................................................. 9

4.3.1 Post-event EDP evaluation ...................................................................................................................................... 9

4.3.2 Periodic reviews ............................................................................................................................................................... 9

4.3.3 Validation of links between phenomena and risk materialization ....................................10

4.3.4 Estimation...........................................................................................................................................................................10

4.3.5 Decision-making ...........................................................................................................................................................10

4.3.6 Guidance on interpretation .................................................................................................................................10

5 The event detection cycle and the role of the EDP ..........................................................................................................10

5.1 The EDP's application of the event detection cycle (the EDP cycle) ......................................................10

5.2 Development and regular review of an EDP-based event detection capability ...........................11

5.2.1 General...................................................................................................................................................................................11

5.2.2 Listing of possible event indicators ..............................................................................................................12

5.2.3 IMT establishment ...................................................................... .................................................................................12

5.2.4 EIT establishment ........................................................................................................................................................12

5.2.5 IMT and EIT periodic review ..............................................................................................................................12

5.3 Deployment of an event detection procedure ...........................................................................................................12

5.3.1 General...................................................................................................................................................................................12

5.3.2 Defining the possibility of an event's occurrence .............................................................................13

5.3.3 Nature of water/wastewater measurement sampling considerations ..........................13

5.3.4 Results assessment .....................................................................................................................................................13

5.3.5 Missing inputs .................................................................................................................................................................14

5.3.6 Unfamiliar combination of inputs ..................................................................................................................14

5.3.7 Deviation from normal frequency detection ........................................................................................14

5.3.8 Measurement grouping ...........................................................................................................................................14

5.4 Classification of events and evaluation of the classification procedure .............................................14

5.4.1 General...................................................................................................................................................................................14

5.4.2 Process-based classification ...............................................................................................................................15

5.4.3 Actual classification ....................................................................................................................................................15

5.4.4 Assignment of weights .............................................................................................................................................16

5.4.5 Frequency calculations ............................................................................................................................................16

5.4.6 Classification efficiency estimation ..............................................................................................................16

5.4.7 Classification evaluation ........................................................................................................................................16

5.5 Notification to relevant personnel/systems ...............................................................................................................16

5.6 Documentation of events ............................................................................................................................................................16

5.6.1 General...................................................................................................................................................................................16

5.6.2 Time stamps......................................................................................................................................................................17

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ISO/TS 24522:2019(E)

5.6.3 Subsequent documentation ................................................................................................................................17

5.6.4 Responsible person documentation ............................................................................................................17

5.6.5 Documentation authority ......................................................................................................................................17

5.6.6 Data security ...................................................................... ...............................................................................................17

5.7 Validation process — Periodic evaluation of the detection process ......................................................17

5.7.1 General...................................................................................................................................................................................17

5.7.2 Confidence-level assignment .............................................................................................................................17

5.8 Periodic system evaluation — System functionality ...........................................................................................18

5.9 EDP development — General principles and governance ..............................................................................18

5.9.1 EDP operation .................................................................................................................................................................18

5.9.2 Access to the EDP .........................................................................................................................................................18

5.9.3 User training and qualification .........................................................................................................................18

5.9.4 Testing and certification .........................................................................................................................................19

5.9.5 EDP output expression ............................................................................................................................................19

5.9.6 EDP output presentation .......................................................................................................................................19

Annex A (informative) Examples of typical event indicators that could be used as EDP inputs .........20

Annex B (informative) Influence matrix table (IMT) ........................................................................................................................27

Annex C (informative) Event identification table (EIT) .................................................................................................................31

Annex D (informative) Examples of statistical methods for the evaluation of event

classification within the EDP ................................................................................................................................................................37

Annex E (informative) Signal measurements' grouping ...............................................................................................................43

Annex F (informative) Verifying the EDP’s response to potential types of events .............................................45

Annex G (informative) Classification of potential events detected ....................................................................................48

Annex H (informative) Event classification performance guide ...........................................................................................53

Bibliography .............................................................................................................................................................................................................................55

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ISO/TS 24522:2019(E)
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 non-governmental, in liaison with ISO, also take part in the work.

ISO collaborates closely with the 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).

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

constitute an endorsement.

For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and

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 224, Service activities relating to drinking

water supply, wastewater and stormwater 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.
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ISO/TS 24522:2019(E)
Introduction

This document has been created in response to an international demand for guidelines on the

development of an event detection process (EDP) for drinking water and wastewater utilities (water

utilities). The EDP is a key element of a water utility's wider event detection system. That system relies

on, and is interrelated to, the water utility's sensor and sampling systems.

This document aims to support water utilities in the development of an EDP that monitors the relevant

variables across their water/wastewater services and evaluates changes in those variables that can

suggest an event has either occurred or could be imminent.

This document aims to be consistent with both the World Health Organization (WHO) Water Safety

Plan approach for water supply and the WHO Sanitation Safety Planning approach for wastewater

collection, treatment and disposal or reuse. Both take a risk-based approach to evaluating uncertainty

about the quality and significance of data that suggests the occurrence of an event.

NOTE 1 This document addresses a wider range of event causation than that implied by the definition of

‘hazard’ in the WHO manuals.

For example (water): a change in the hardness of the water supplied could remain within acceptable limits for

public health purposes but could still represent a change in water quality of material interest to some service

users (e.g. breweries).

For example (wastewater): ingress of a volatile chemical into the wastewater system ought not to represent

a direct health hazard in all circumstances, but, depending on its concentrations, could result in an explosion

within the network or fire damage to the wastewater infrastructure.

Outputs from an EDP could help inform those within the water utility responsible for identifying events

and alerting individuals responsible for event response decision-making. Such alerts could be required

despite uncertainty about the quality and reliability of the data currently available.

Event response decisions can be based on those decision makers’ knowledge, experience and

assessment of the cause(s) and effect(s) of the event as it unfolds – including consideration of the EDP’s

outputs where appropriate.

At the discretion of the water utility, design of the EDP could incorporate elements of automated

decision-making.

NOTE 2 If automated decision-making is proposed, consideration could require distinguishing between

situations where automation could be appropriate and those where it would not be. For example, automation

with low-impact outcomes could be acceptable but automation with high-impact outcomes could require greater

caution. When considering automation, it is advisable to consider the appropriateness of inputs, the complexity

of the system, the nature of the water utility and the effect of time delays.

A decision on whether to implement the water utility’s procedure for dealing with an abnormal situation

could be required in response to an identified or suspected event.

Such a decision could depend upon the confidence in the EDP’s classification and output and the process

underpinning it.

The guidelines could be of particular use to those water utilities that wish to enhance their ability to

recognize abnormal events as a means to: maintain or improve public health provision; improve their

operational processes; enhance the levels of their service provision; or reduce risks to the continued

delivery of existing service levels.

In addition, development of an EDP can be a valuable aid to organizational learning and memory. The

existence of an effective and efficient EDP provides a significant control against the risk of loss of

individuals’ knowledge and expertise by increasing a water utility’s independence from such vulnerable

resources. Regular use and review of an EDP’s successes and failures can contribute to organizational

learning and a reduction in the time taken to detect an event.
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TECHNICAL SPECIFICATION ISO/TS 24522:2019(E)
Event detection process: Guidelines for water and
wastewater utilities
1 Scope

This document provides guidance for water utilities on the detection and classification of water and

wastewater events.
The following subjects are within the scope of this document:

— publicly and privately owned and operated water utilities. It does not favour any particular

ownership or operating model;
— all aspects of the drinking water system and the wastewater system;

— all causes of abnormal changes in water and/or wastewater service provision capable of detection

by monitoring systems including accidents, unexpected operational changes, natural hazards and

intentional disruption.

This document is independent of the measurement methods used to collect the data.

The document focuses on events which could imminently affect the water utility’s interested parties.

The following are outside the scope of this document:
— methods of design and construction of drinking water and wastewater systems;
— plumbing and drainage systems not under the control of the water utility.

This document does not include details about action taken as a result of event detection. For such details

see ISO 24518 and EN 15975 Part 1.
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 24513, Activities relating to drinking water, wastewater and stormwater services — Vocabulary

3 Terms and definitions

For the purposes of this document, the terms and definitions given in ISO 24513 and the following apply.

ISO and IEC maintain terminological databases for use in standardization at the following addresses:

— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
classification
category that the event (3.5) falls into
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ISO/TS 24522:2019(E)
3.2
continual improvement
recurring activity to enhance performance (3.15)

Note 1 to entry: The process (3.16) of establishing objectives (3.13) and finding opportunities for improvement

is a continual process through the use of audit findings and audit conclusions, analysis of data, management

reviews or other means and generally leads to corrective action or preventive action.

Note 2 to entry: The nature of the activity can differ between cycles of recurrence.

[SOURCE: ISO 9000: 2015, 3.3.2, modified — Note 2 to entry replaced.]
3.3
documented information

information required to be controlled and maintained by an organization (3.14) and the medium on

which it is contained

Note 1 to entry: Documented information can be in any format and media and from any source.

Note 2 to entry: Documented information can refer to:
— the management system, including related processes (3.16);

— information created in order for the organization (3.14) to operate (documentation);

— evidence of results achieved (records).
3.4
effectiveness
extent to which planned activities are realized and planned results are achieved
3.5
event
situation where a behaviour deviates from the normal

Note 1 to entry: An event can be one or more occurrences, and can have several causes.

Note 2 to entry: An event can consist of something not happening.

Note 3 to entry: An event can sometimes be referred to as an “incident” or “accident”.

Note 4 to entry: An event without consequences can also be referred to as a “near miss”, “incident”, “near hit” or

“close call”.

Note 5 to entry: For the purposes of this document, “normal” refers to what is expected.

3.6
event detection
recognition of event indicator (3.9) and/or information about a new situation
Note 1 to entry: New situations can be sorted into one of the following:
— event indicator and/or situation(s) are considered known and non-hazardous;

— event indicator and/or situation(s) are considered hazardous, but a procedure to handle them already exists;

— event indicator and situation(s) are considered unknown, and for which a procedure does not yet exist.

3.7
event detection process
EDP

set of interrelated or interacting activities which transforms inputs [data or information on an actual or

suspected event (3.5)] into outputs [to support the water utility’s (3.19) operational activities]

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ISO/TS 24522:2019(E)
3.8
event identification table
EIT

table developed by the organization (3.14) that contains examples of proven connections between

changes in water measurements and possible causation types
3.9
event indicator

signal to the water utility or one or more stakeholders (3.18) that an event (3.5) can have occurred with

the potential to cause a significant deviation in the users' expectations of service performance (3.15)

Note 1 to entry: The signal can exist yet remain unobserved for a period.
3.10
influence matrix table
IMT

table developed by the water utility (3.19) that contains suspected connections between event

indicators (3.9) and performance measurements (3.11) based on scientific knowledge and water industry

experience
3.11
measurement
process (3.16) to determine a value
3.12
monitoring
determining the status of a system, a process (3.16) or an activity

Note 1 to entry: To determine the status there can be a need to check, supervise or critically observe.

3.13
objective
result to be achieved
Note 1 to entry: An objective can be strategic, tactical or operational.

Note 2 to entry: Objectives can relate to different disciplines (such as finance, health and safety, and environmental

goals) and can apply at different levels [such as strategic, organization-wide, project, product and process (3.16)].

Note 3 to entry: An objective can be expressed in other ways, for example as an intended outcome, a purpose, an

operational criterion, an event detection objective or by the use of other words with similar meaning (e.g. aim,

goal or target).

Note 4 to entry: In the context of an event detection system, event detection objectives are set by the water utility

(3.19), consistent with the event detection management policy, to achieve specific results.

3.14
organization

person or group of people that has its own functions with responsibilities, authorities and relationships

to achieve its objectives (3.13)

Note 1 to entry: The concept of organization includes, but is not limited to, sole-trader, company, corporation,

firm, enterprise, authority, partnership, association, charity or institution, or part or combination thereof,

whether incorporated or not, public or private.

Note 2 to entry: For the purposes of this document the organization responsible for event detection (3.6) will

usually be part of a wider organization [the water utility (3.19) responsible for the provision of drinking water/

wastewater services].
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ISO/TS 24522:2019(E)
3.15
performance
measurable result

Note 1 to entry: Performance can relate either to quantitative or qualitative findings.

Note 2 to entry: Performance can relate to the management of activities, processes (3.16), products (including

services), systems or organizations (3.14).
3.16
process

set of interrelated or interacting activities that use inputs to deliver an intended result

Note 1 to entry: Whether the “intended result” of a process is called an output, product or service depends on the

context of the reference.

Note 2 to entry: Inputs to a process are generally the outputs of other processes and outputs of a process are

generally the inputs to other processes.

Note 3 to entry: Two or more interrelated and interacting processes in series can also be referred to as a process.

Note 4 to entry: Processes in an organization (3.14) are generally planned and carried out under controlled

conditions to add value.

Note 5 to entry: A process where the conformity of the resulting output cannot be readily or economically

validated is frequently referred to as a “special process”.
3.17
risk

combination of the likelihood of a hazardous event and the severity of consequences, if the hazard

occurs in the drinking water system or wastewater system

Note 1 to entry: Risk is often characterized by reference to potential events (3.5) and consequences or a

combination of these.

Note 2 to entry: The English term “likelihood” does not have a direct equivalent in some languages; instead, the

equivalent of the term “probability” is often used. However, in English, “probability” is often narrowly interpreted

as a mathematical term. Therefore, in risk management terminology, “likelihood” is used with the intent that it

has the same broad interpretation as the term “probability” has in many languages other than English.

Note 3 to entry: Ris
...