prEN ISO 15883-4

• Abstract:

  This document specifies the particular requirements, including performance criteria for washer-disinfectors (WD) that are intended to be used for cleaning and chemical disinfection of thermolabile endoscopes.; This document also specifies the performance requirements for the cleaning and disinfection of the washer-disinfector and its components and accessories which can be required to achieve the necessary performance criteria.; The methods, instrumentation and instructions required for type testing, works testing, validation (installation, operational and performance qualification on first installation), routine control and monitoring, and requalification of WD periodically and after essential repairs, are also specified.; NOTE 1 In addition, Annex A gives guidance on an appropriate division of responsibility for the range of activities covered by this document.; NOTE 2 WD complying with this document can also be used for cleaning and chemical disinfection of other thermolabile re-usable medical devices for which the device manufacturer has recommended and validated this method of disinfection.; WD complying with the requirements of this document are not intended for cleaning and disinfection of medical devices, including endoscopic accessories, which are heat stable and can be disinfected or sterilized by thermal methods (see ISO 15883-1:2006+Amd 1:2014, 4.1.5).; The specified performance requirements of this document do not ensure the inactivation or removal of the causative agent(s) (prion protein) of transmissible spongiform encephalopathies.; NOTE 3 If it is considered that prion protein might be present, particular care is needed in the choice of cleaning agents and disinfectants to ensure that the chemicals used do not react with the prion protein and/or other protein in a manner that can inhibit its removal or inactivation from the load or washer-disinfector.; NOTE 4 This document can be used by prospective purchasers and manufacturers as the basis of agreement on the specification of the WD, manufacturers of endoscopes, cleaning products, and disinfecting products.

• Status: Not Published
• Publication Date: 12-Mar-2028
• ICS: 11.080.10 - Sterilizing equipment
• Technical Committee: CEN/TC 102 - Sterilizers for medical purposes
• Drafting Committee: CEN/TC 102/WG 8 - Performance requirements and testing for washer-disinfectors
• Current Stage: 4020 - Submission to enquiry - Enquiry
• Start Date: 24-Sep-2026
• Completion Date: 24-Sep-2026
• Directive: 2017/745 - Regulation (EU) 2017/745 of the European Parliament and of the Council of 5 April 2017 on medical devices, amending Directive 2001/83/EC, Regulation (EC) No 178/2002 and Regulation (EC) No 1223/2009 and repealing Council Directives 90/385/EEC and 93/42/EEC
• Mandate: M/575 - Medical devices in support of Regulation (EU) 2017/745 and in vitro diagnostic medical devices in support of Regulation (EU) 2017/746
• Mandate: M/575 Amd 2 - Medical devices in support of Regulation (EU) 2017/745 and in vitro diagnostic medicial devices in support of Regulation (EU) 2017746
• Ref Project: oSIST prEN ISO 15883-4:2026 - Washer-disinfectors - Part 4: Requirements and tests for washer-disinfectors employing chemical disinfection for thermolabile endoscopes (ISO/DIS 15883-4:2026)

• Revises: EN ISO 15883-4:2018 - Washer-disinfectors - Part 4: Requirements and tests for washer-disinfectors employing chemical disinfection for thermolabile endoscopes (ISO 15883-4:2018)
• Effective Date: 24-Jul-2024

prEN ISO 15883-4 is the CEN draft standard for washer-disinfectors that use chemical disinfection for thermolabile endoscopes. It specifies how these washer-disinfectors are to clean, disinfect, rinse, dry, self-disinfect, and be tested so that they are suitable for their intended use. The document is written for manufacturers, purchasers, users, and process-chemical suppliers who need a shared technical specification.

What does prEN ISO 15883-4 specify?

prEN ISO 15883-4 sets particular requirements and performance criteria for washer-disinfectors intended for thermolabile endoscopes. It also covers the methods, instruments, and instructions needed for type testing, works testing, validation, routine control and monitoring, and requalification after repairs or on a periodic basis.

The scope is focused on chemical disinfection for devices that can be immersed in water or aqueous solutions. It is not intended for heat-stable medical devices or accessories that can be disinfected or sterilized by thermal methods. The scope also notes that the performance requirements do not guarantee inactivation or removal of prion protein.

Annex A gives guidance on how responsibility can be divided between the washer-disinfector manufacturer, the endoscope manufacturer, the process chemical manufacturer, and the purchaser or user.

Annex	What it covers
A	Summary of activities and a practical division of responsibility
B	Microbiological testing of chemical disinfection efficacy of the load
C	Summary of test programmes
D	Methods for microbiological evaluation of disinfection of liquid transport systems
E	Tests for microbial contamination of final rinse water
F	Additional notes on microbiological testing of chemical disinfection processes
G	Typical specifications of trumpet valves and connection ports
H	Establishing endoscope type test groups
I	Establishing endoscope product families
J	Test soils and methods for cleaning and full process tests
K	Tests on biofilm
L	Load dryness
ZA	Relationship with Regulation (EU) 2017/745

What are the key requirements of prEN ISO 15883-4?

prEN ISO 15883-4 builds on ISO 15883-1:2024 and adds endoscope-specific requirements for fluid handling, cleaning, chemical disinfection, rinsing, drying, and testing. In practice, it tells the manufacturer what the WD must control, what the user must be told, and what evidence is needed to show the process works on the intended endoscopes.

General design and process control

Clause 4 requires the WD to conform to ISO 15883-1:2024 except for the specific additions in this part. The WD must control process variables that affect cycle efficacy, including water volume, chemical dose, and the way different process chemicals are separated or identified.

This matters because endoscope reprocessing depends on repeatable control of flow, concentration, and temperature. The document also requires instructions for use to tell the user which preparatory actions are needed to achieve effective processing.

Leak testing and channel handling

Clause 4.2 covers leak testing for endoscopes that need it. The WD must have either a manual or automatic leak-test system, and when an automatic leak test fails the controller must stop the cycle. The user must also be warned by an audible or visible signal.

Clauses 5.2 and 6.5 extend this by requiring verification of channel irrigation and tests for non-connection, obstruction, and leak-test behavior. In practice, this is meant to prevent a cycle from running with a missing connector, a blocked channel, or an endoscope that is not correctly connected.

Cleaning and disinfection stages

Clauses 4.3 and 4.4 set requirements for the cleaning and chemical disinfection stages. The detergent must be the specified one, it must not be used past its permitted life, and the washing stage temperature has to be monitored. For disinfection, the process conditions must cover disinfectant concentration, volume, temperature, and contact time.

The document also requires evidence that the chosen disinfectant has the right antimicrobial spectrum for the intended use. It says cleaning matters before disinfection because residue and other soils can reduce disinfectant performance.

Rinsing, purging, and drying

Clause 4.5 requires final rinse water to meet chemical and microbiological quality requirements, including control of bacterial endotoxins. Clause 4.6 requires a means to purge rinse water from endoscope channels, and when air is used it must be oil free and filtered.

Clause 4.7 covers drying. Where a drying stage is provided, the air quality must meet the same standard as the purge air, and Annex L is used to check for residual droplets or residual water. This matters because retained moisture can support contamination after reprocessing.

Self-disinfection and water treatment

Clause 4.8 requires a self-disinfection cycle for the WD. The document distinguishes thermal and chemical self-disinfection and requires evidence appropriate to the system used. Clause 4.9 covers water treatment equipment and the disinfection of that equipment, including treatment of incoming water used for the final rinse.

In practice, this means the WD must protect itself as well as the load. A contaminated internal water path or transport system can compromise later cycles, so the document requires the system to be kept under control and to be requalified after relevant failures.

Testing, documentation, and supplier information

Clause 6 sets out the conformity tests, and Clause 8 sets out the information that must be supplied. The test programme includes type, works, operational qualification, performance qualification, and routine tests. Annex C summarizes which devices are used at each stage, and it allows surrogate devices where justified.

Clause 8 requires the supplier to state which endoscopes have evidence of satisfactory processing, what connectors and flow conditions are needed, the pressure and flow limits, the maximum process temperature, the permitted leak-test variation, and the parts covered by self-disinfection. This is the information a buyer or user needs to decide whether the WD fits their endoscope set.

What terms does prEN ISO 15883-4 define?

prEN ISO 15883-4 uses the terms from ISO 15883-1:2024 and adds several endoscope-specific terms in Clause 3.

• Air break - a physical separation in water supply piping that prevents backflow from equipment.
• Endoscope product family - a group of endoscopes with comparable design, channel count, construction, and purpose.
• Endoscope type test group - endoscopes with similar channel design and similar flow-related characteristics, used to reduce the number of type tests.
• Irrigation plan - the required direction of process-fluid flow through specified endoscope channels.
• Minimum effective concentration (MEC) - the lowest concentration of a chemical that achieves the claimed activity in the process.
• Minimum recommended concentration (MRC) - the lowest concentration specified for use in the process.
• Thermolabile - readily damaged by heat.
• Worst-case - the set of conditions most likely to challenge the process or product.

Who uses prEN ISO 15883-4?

prEN ISO 15883-4 is used by washer-disinfector manufacturers, endoscope manufacturers, process chemical manufacturers, purchasers, and users. It is also relevant to validation specialists, requalification teams, and hospital reprocessing departments.

In practice, manufacturers use it to design and type-test WD systems, define compatible endoscope ranges, and write instructions for use. Healthcare facilities use it to check installation, operational and performance qualification, routine control, and whether the selected washer-disinfector matches their endoscope inventory and local water quality.

What changed in prEN ISO 15883-4 from the previous edition?

prEN ISO 15883-4 is the third edition and replaces ISO 15883-4:2018. The foreword states these main changes:

• normative references were revised to ISO 15883-1:2024 and ISO 15883-5:2021
• terms and definitions were aligned with ISO 11139:2018 and Amendment 1:2024
• monitoring for reuse of disinfectants was added
• Annex B was revised so testing is for Mycobacteria only
• Annex J was added for flexible endoscope soiling
• Annex K was added for biofilm testing
• Annex L was added for load dryness
• the bibliography was revised

Which standards are used with prEN ISO 15883-4?

prEN ISO 15883-4 depends on several other standards to define its baseline requirements and test methods.

• ISO 15883-1:2024 - gives the general washer-disinfector requirements, terms and definitions, and base tests.
• ISO 15883-5:2021 - provides the performance requirements and test criteria for demonstrating cleaning efficacy.
• EN 12353 - covers preservation of the test organisms used to determine antimicrobial activity.
• EN 13727 - provides the quantitative suspension test for bactericidal activity in the medical area.
• The introduction also points users to IEC 61010-2-040 for safety requirements for washer-disinfectors.

What does the prEN ISO 15883-4 document contain?

prEN ISO 15883-4 contains a full test and validation framework for thermolabile endoscope washer-disinfectors. It includes reference tests for leak testing, channel non-obstruction, channel non-connection, thermometric checks, dosing checks, cleaning efficacy, disinfectant efficacy, self-disinfection, water treatment performance, and drying.

The annexes add practical tools: microbiological methods in Annex B and D, test-program summaries in Annex C, surrogate-device and test-group methods in Annex H, product-family guidance in Annex I, specific soil and full-cycle methods in Annex J, and biofilm testing in Annex K. Annex G shows typical trumpet valve and port arrangements, while Annex ZA maps selected clauses to Regulation (EU) 2017/745.

SLOVENSKI STANDARD
01-november-2026
Čistilno-dezinfekcijske naprave - 4. del: Zahteve in preskusi za čistilno-
dezinfekcijske naprave s kemično dezinfekcijo za termolabilne endoskope
(ISO/DIS 15883-4:2026)
Washer-disinfectors - Part 4: Requirements and tests for washer-disinfectors employing
chemical disinfection for thermolabile endoscopes (ISO/DIS 15883-4:2026)
Reinigungs-Desinfektionsgeräte - Teil 4: Anforderungen und Prüfverfahren für
Reinigungs-Desinfektionsgeräte mit chemischer Desinfektion für thermolabile
Endoskope (ISO/DIS 15883-4:2026)
Laveurs désinfecteurs - Partie 4: Exigences et essais pour les laveurs désinfecteurs
destinés à la désinfection chimique des endoscopes thermolabiles (ISO/DIS 15883-
4:2026)
Ta slovenski standard je istoveten z: prEN ISO 15883-4
ICS:
11.080.10 Sterilizacijska oprema Sterilizing equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 15883-4
ISO/TC 198
Washer-disinfectors —
Secretariat: ANSI
Part 4:
Voting begins on:
Requirements and tests for washer- 2026-09-21
disinfectors employing chemical
Voting terminates on:
2026-12-14
disinfection for thermolabile
endoscopes
Laveurs désinfecteurs —
Partie 4: Exigences et essais pour les laveurs désinfecteurs
destinés à la désinfection chimique des endoscopes thermolabiles
ICS: 11.080.10
THIS DOCUMENT IS A DRAFT CIRCULATED
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Reference number
ISO/DIS 15883-4:2026(en)
DRAFT
ISO/DIS 15883-4:2026(en)
International
Standard
ISO/DIS 15883-4
ISO/TC 198
Washer-disinfectors —
Secretariat: ANSI
Part 4:
Voting begins on:
Requirements and tests for washer-
disinfectors employing chemical
Voting terminates on:
disinfection for thermolabile
endoscopes
Laveurs désinfecteurs —
Partie 4: Exigences et essais pour les laveurs désinfecteurs
destinés à la désinfection chimique des endoscopes thermolabiles
ICS: 11.080.10
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
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Published in Switzerland Reference number
ISO/DIS 15883-4:2026(en)
ii
ISO/DIS 15883-4:2026(en)
Contents Page
Foreword .vi
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Performance requirements . . 5
4.1 General .5
4.2 Systems for leak testing .7
4.3 Cleaning .8
4.3.1 General .8
4.3.2 Flushing stage .8
4.3.3 Washing stage .8
4.3.4 Post-wash rinsing stage .9
4.3.5 Determination of cleaning efficacy .9
4.4 Disinfecting .9
4.4.1 General .9
4.4.2 Efficacy of the disinfectant .10
4.4.3 Temperature .10
4.4.4 Process monitoring .11
4.4.5 Disinfectant use .11
4.5 Final rinsing stage . 12
4.6 Purging to remove rinse water . 12
4.7 Drying stage . 12
4.8 Self-disinfection . 12
4.9 Water treatment equipment .14
4.9.1 General .14
4.9.2 Disinfection of water treatment equipment .14
4.9.3 Maintenance of piping . 15
5 Mechanical and process requirements .15
5.1 Design, manufacture and construction . 15
5.2 Device channel irrigation system . 15
5.2.1 General . 15
5.2.2 Verification of device channel irrigation by the automatic controller .16
5.3 Venting and drainage systems.17
5.4 Temperature control .17
5.4.1 General .17
5.4.2 Temperature control of the washing stage .17
5.4.3 Temperature control of the disinfection stage .17
5.4.4 WD with a minimum operating temperature for the washing or disinfection
stage, or both .17
5.5 Process chemicals .18
5.6 Process verification .18
5.7 Dosing systems . .18
6 Testing for conformity .18
6.1 General .18
6.2 Test equipment .19
6.2.1 General .19
6.2.2 Pressure measurement .19
6.2.3 Flow measurement .19
6.3 Water used for final rinsing .19
6.3.1 Principle .19
6.3.2 Material/procedure .19
6.3.3 Results/acceptance criteria . .19

iii
ISO/DIS 15883-4:2026(en)
6.4 Hardness of water used during type testing . 20
6.4.1 Principle . 20
6.4.2 Material. 20
6.4.3 Procedure . 20
6.5 Leak test . 20
6.5.1 Principle . 20
6.5.2 Material. 20
6.5.3 Procedure .21
6.5.4 Results/acceptance criteria . .21
6.6 Channels non-obstruction test . 22
6.6.1 Principle . 22
6.6.2 Material. 22
6.6.3 Procedure .24
6.6.4 Results/acceptance criteria . .24
6.7 Channels non-connection test .24
6.7.1 Principle .24
6.7.2 Material.24
6.7.3 Procedure .24
6.7.4 Result/acceptance criteria .24
6.8 Thermometric tests . 25
6.8.1 Test for chamber and load temperature during operating cycle . 25
6.8.2 Test for operating cycle temperature limits on washing and chemical
disinfection stages . 25
6.9 Chemical dosing tests for single-dose containers . 26
6.9.1 Principle . 26
6.9.2 Material. 26
6.9.3 Procedure . 26
6.9.4 Results/acceptance criteria . . 26
6.10 Tests of cleaning efficacy . 26
6.10.1 Tests of cleaning efficacy of the load . 26
6.10.2 Tests of cleaning efficacy of the load carriers and chamber walls . 28
6.11 Tests of disinfection efficacy . . 28
6.11.1 General . 28
6.11.2 Preliminary tests on chemical disinfectants . 29
6.11.3 Self-disinfection tests .31
6.11.4 Test of microbial quality of final rinse water treatment equipment .32
6.11.5 Disinfection of liquid transport systems following failure of water treatment
equipment .32
6.11.6 Chemical disinfection of the load . 33
7 Documentation and inspection .34
8 Information to be supplied .34
9 Marking, labelling and packaging .35
10 Information to be requested from the purchaser by the WD supplier .35
Annex A (informative) Summary of activities covered by this document .36
Annex B (normative) Microbiological testing of the efficacy of chemical disinfection of the load .38
Annex C (normative) Summary of test programmes . 41
Annex D (normative) Methods for microbiological evaluation of disinfection of liquid transport
system.45
Annex E (normative) Tests for microbial contamination of final rinse water.50
Annex F (informative) Additional notes on microbiological testing of chemical disinfection
processes .52
Annex G (informative) Typical specifications of trumpet valves and connection ports .54
Annex H (normative) Establishing endoscope type test groups .60

iv
ISO/DIS 15883-4:2026(en)
Annex I (informative) Establishing endoscope product families .69
Annex J (normative) Test soils and methods for cleaning and full process tests .73
Annex K (normative) Tests on biofilm .82
Annex L (informative) Load dryness .87
Annex ZA (informative) Relationship between this European Standard and the General Safety
and Performance Requirements of Regulation (EU) 2017/745 aimed to be covered .89
Bibliography .93

v
ISO/DIS 15883-4:2026(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 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).
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 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 198, Sterilization of health care products.
This third edition cancels and replaces the second edition (ISO 15883-4:2018) which has been technically
revised.
The main changes are as follows:
— revision of normative references to ISO 15883-1:2024 and ISO 15883-5:2021;
— alignment of terms and definitions with ISO 11139:2018 & Amd 1:2024;
— requirement for monitoring reuse of disinfectants (4.4.5.2);
— revision of Annex B: modified for testing for Mycobacteria only;
— addition of Annex J: test soiling method for flexible endoscopes;
— addition of Annex K: biofilm test;
— addition of Annex L: load dryness test;
— revision of the Bibliography.
A list of all parts in the ISO 15883 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.

vi
ISO/DIS 15883-4:2026(en)
Introduction
This introduction is intended to be read in conjunction with the introduction to ISO 15883-1.
The washer-disinfectors (WD) specified in this document are intended to process devices that can be
immersed in water or aqueous solutions. For some devices this will require that, prior to processing, relevant
parts of the device are protected from immersion in accordance with the device manufacturer’s operating
instructions.
Fields of application within the scope of the ISO series include laboratory, veterinary, dental and
pharmaceutical applications and other specific applications, such as washer-disinfectors for bedsteads
and transport carts and the disinfection of crockery and cutlery intended for use with immunologically
compromised patients.
Requirements for WD for other applications are specified in other parts of ISO 15883.
Safety requirements for WD are given in IEC 61010-2-040.
NOTE Local or national regulations can apply in respect of the potential adverse effects on the quality of water
intended for human consumption or environmental impacts caused by the WD and its intended use.

vii
DRAFT International Standard ISO/DIS 15883-4:2026(en)
Washer-disinfectors —
Part 4:
Requirements and tests for washer-disinfectors employing
chemical disinfection for thermolabile endoscopes
1 Scope
This document specifies the particular requirements, including performance criteria for washer-disinfectors
(WD) that are intended to be used for cleaning and chemical disinfection of thermolabile endoscopes.
This document also specifies the performance requirements for the cleaning and disinfection of the WD and
its components and accessories which can be required to achieve the necessary performance criteria.
The methods, instrumentation and instructions required for type testing, works testing, validation
(installation, operational and performance qualification on first installation), routine control and
monitoring, and requalification of WD periodically and after essential repairs, are also specified.
NOTE 1 In addition, Annex A gives guidance on an appropriate division of responsibility for the range of activities
covered by this document.
NOTE 2 WD conforming with this document can also be used for cleaning and chemical disinfection of other
thermolabile re-usable medical devices for which the device manufacturer has recommended and validated this
method of disinfection.
WD conforming with the requirements of this document are not intended for cleaning and disinfection of
medical devices, including endoscopic accessories, which are heat stable and can be disinfected or sterilized
by thermal methods (see ISO 15883-1:2024, 4.1.5).
NOTE 3 The specified performance requirements of this document cannot ensure the inactivation or removal of the
causative agent(s) (prion protein) of transmissible spongiform encephalopathies.
NOTE 4 If it is considered that prion protein might be present, particular care is needed in the choice of cleaning
agents and disinfectants to ensure that the chemicals used do not react with the prion protein or other protein in a
manner that can inhibit its removal or inactivation from the load or WD.
NOTE 5 This document can be used by prospective purchasers and manufacturers as the basis of agreement on the
specification of the WD, manufacturers of endoscopes, cleaning products, and disinfecting products.
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 15883-1:2024, Washer-disinfectors — Part 1: General requirements, terms and definitions and tests
ISO 15883-5:2021, Washer-disinfectors — Part 5: Performance requirements and test method criteria for
demonstrating cleaning efficacy
EN 12353, Chemical disinfectants and antiseptics — Preservation of test organisms used for the determination
of bactericidal (including Legionella), mycobactericidal, sporicidal, fungicidal and virucidal (including
bacteriophages) activity
ISO/DIS 15883-4:2026(en)
EN 13727, Chemical disinfectants and antiseptics — Quantitative suspension test for the evaluation of
bactericidal activity in the medical area — Test method and requirements (phase 2, step 1)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 15883-1:2024 and the following
apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
air break
physical separation in water supply pipes to prevent back flow from equipment
[SOURCE: ISO 11139:2018, 3.8]
3.2
analyte
chemical substance that is the subject of chemical analysis
[SOURCE: ISO 11139:2018, 3.12]
3.3
block
group of channels comprising part of an endoscope with specified lengths, diameters and
interconnections
[SOURCE: ISO 11139:2018, 3.30]
3.4
channel separator
device used to keep apart interconnected fluid pathways
EXAMPLE A device inserted in a trumpet valve cylinder where multiple channels meet in order to separate the air
and water pathways in the air/water valve assembly.
[SOURCE: ISO 11139:2018, 3.40]
3.5
colony forming unit
CFU
visible aggregation of microorganisms arising from a single cell or multiple cells
[SOURCE: ISO 11139:2018, 3.53]
3.6
disinfecting agent
physical or chemical agent used for disinfection
[SOURCE: ISO 11139:2018, 3.83]
3.7
endoscope connector
device to interface with the fluid entry port of a channel of an endoscope that, where applicable, includes the
tubing connected to the channel irrigation system of the washer-disinfector
[SOURCE: ISO 11139:2018, 3.94]

ISO/DIS 15883-4:2026(en)
3.8
endoscope leak test
set of actions to identify a loss of integrity
Note 1 to entry: The test is intended to establish that the surface covering the device and/or lining a device channel is
intact to the extent necessary to maintain a slightly positive pressure.
[SOURCE: ISO 11139:2018, 3.95, modified — Note 1 to entry has been added.]
3.9
endoscope port
part of an endoscope to which the irrigation system of the washer-disinfector is connected to irrigate all or
part of a channel
[SOURCE: ISO 11139:2018, 3.96]
3.10
endoscope product family
group of endoscopes with comparable design, including the number, construction, and purpose of the
different endoscope channels
[SOURCE: ISO 11139:2018, 3.97]
3.11
endoscope surrogate device
item designed to represent construction elements of endoscope specific characteristics affecting the flow
conditions in endoscope channels
Note 1 to entry: Elements can include channel length and diameter, connectors, channel separators, port closures,
return valves, etc.
[SOURCE: ISO 11139:2018, 3.98]
3.12
endoscope type test group
endoscopes for which the general channel design and specific characteristics affecting the flow conditions
in the endoscope are similar
Note 1 to entry: The general channel design includes lengths and diameters. Characteristics affecting the flow
conditions in the endoscope are, for example, endoscope connectors, channel separators, port closures, non-return
valves.
Note 2 to entry: Similar implies that small variations can be possible. Endoscopes that show small variations in channel
specifications that do not lead to a significant variation in the flow and pressure characteristic through the channels
could be in the same endoscope type test group.
[SOURCE: ISO 11139:2018, 3.99, modified — Note 1 to entry has been modified.]
3.13
inoculated carrier
supporting material on or in which a specified number of viable test microorganisms has been deposited
[SOURCE: ISO 11139:2018, 3.144]
3.14
irrigation plan
stipulated direction of flow of process fluids through the specified channels
of an endoscope
[SOURCE: ISO 11139:2018, 3.148]

ISO/DIS 15883-4:2026(en)
3.15
liquid transport systems
components of equipment used to store, pump, or transport water and/or solutions,
excluding pipework before the air break
[SOURCE: ISO 11139:2018, 3.154]
3.16
microbial inactivation factor
measured change in microbial population caused by the lethal effect of the disinfection or sterilization
process
Note 1 to entry: It is expressed as log .
[SOURCE: ISO 11139:2018, 3.173]
3.17
microbial resistance
ability of a microorganism or population of microorganisms to withstand a microbial reduction process
Note 1 to entry: This refers to resistance of microorganisms to disinfectants used in a WD.
[SOURCE: ISO 11139:2018, 3.175, modified — Note 1 to entry has been added.]
3.18
minimum effective concentration
MEC
lowest concentration of a chemical or product, used in a specified process, that achieves a claimed activity
[SOURCE: ISO 11139:2018, 3.177]
3.19
minimum recommended concentration
MRC
lowest concentration of a chemical or product specified for use in a process
[SOURCE: ISO 11139:2018, 3.178]
3.20
obstruction
partial or complete blockage
[SOURCE: ISO 11139:2018, 3.187]
3.21
port closure
device to close an endoscope port during processing in order to maintain the flow of process
fluids throughout the length of the endoscope
EXAMPLE To close the suction valve port.
[SOURCE: ISO 11139:2018, 3.198]
3.22
thermolabile
readily damaged by heat
[SOURCE: ISO 11139:2018, 3.302]

ISO/DIS 15883-4:2026(en)
3.23
worst-case
set of conditions, as compared with ideal conditions, justified to pose the highest probability of process or
product failure
Note 1 to entry: The set of conditions do not necessarily induce product or process failure.
Note 2 to entry: The set of conditions should be specified within the limitations of the intended use.
Note 3 to entry: The set of conditions should encompass upper and lower processing limits and circumstances.
[SOURCE: ISO 11139:2018/Amd 1:2024, 3.376]
4 Performance requirements
4.1 General
4.1.1 The WD shall conform to ISO 15883-1: 2024 with the exception of the following subclauses:
a) ISO 15883-1:2024, 4.2.3 (washing stage, modified by 4.3.3 of this document);
b) ISO 15883-1:2024, 4.3.1 (specification for thermal disinfection of the load, load carrier(s) and chamber
walls during a standard cleaning and disinfection cycle is not applicable to this document);
c) ISO 15883-1:2024, 5.1.2.8 (entry port requirement for temperature sensors) modified by 5.1.3 of this
document;
d) ISO 15883-1:2024, 5.3.5 (microbial quality of final rinse water, modified by 4.5 of this document);
e) ISO 15883-1:2024, 5.9 (process temperature control limits, modified by 5.4 of this document);
f) ISO 15883-1:2024, 6.4.2.1 (test for quality of final rinse water – sampling, modified by 6.3 and Annex E
of this document);
g) ISO 15883-1:2024, 6.5.5 (test for chamber venting to prevent pressurization by steam is not applicable
to this document);
h) ISO 15883-1:2024, 6.8.2 (load temperature test, modified by 6.8.1 of this document);
i) ISO 15883-1:2024, 6.8.3 (chamber wall temperature test, replaced by 6.8.1 of this document);
j) ISO 15883-1:2024, 6.10 (cleaning type test, modified by 6.10 of this document).
4.1.2 Each device, including any device channels or cavities, shall be processed by the WD as follows:
a) leak testing (where specified) in accordance with 4.2;
b) cleaning (which may include several stages) in accordance with 4.3;
c) disinfecting in accordance with 4.4;
d) final rinsing in accordance with 4.5;
e) purging of rinse water in accordance with 4.6;
f) drying (when appropriate) in accordance with 4.7.
4.1.3 After the complete process in the WD the endoscope shall be safe for its intended use. The
combination of the cleaning, disinfection and rinsing process shall be designed to achieve this condition,
recognizing the high level of microbial and other contamination that can exist (see References [1], [2], [3]).
Other factors such as the design of endoscope connectors shall be taken into consideration. This capability

ISO/DIS 15883-4:2026(en)
shall be demonstrated during type testing for endoscopes that the WD is designed to process [see also 8 a), 8
b) and 8 c)].
Demonstration of the capability of the complete cycle efficacy shall be provided during additional type
testing by employing the methods described in Annex J, using the organism(s) previously established during
in vitro tests as most resistant to the disinfectant under in-use conditions and on endoscopes that are
representative for each relevant endoscope type test group [see 8 a) and Annex H].
According to the nature of the most resistant microorganism selected the minimum log reduction obtained
at each test site (see J.7.2) after a complete standard cycle for that microorganism(s) shall be:
— 9 log for vegetative bacteria;
— 6 log for fungal spores;
— 6 log for mycobacteria; or
— 4 log for bacterial endospores.
NOTE 1 In order to limit the work load the type tests can be performed on representative endoscopes from
endoscope type test groups (see Annex H to establish relevant endoscope type test groups).
NOTE 2 The efficacy of the process (including cleaning and disinfection) depends on a number of factors which
include:
a) the nature (characteristics) of the device being processed;
b) the extent and nature of the soiling to be removed;
c) the temperature of the process;
d) the mechanical energy (type, output);
e) purging to remove rinse water;
f) the detergent system;
g) the nature, volume, concentration and temperature of the cleaning and disinfectant solutions and their ability to
wet the surfaces to be cleaned and disinfected;
h) the duration of the various process stages;
i) the removal of suspended soil.
4.1.4 The instructions for use of the WD shall recommend that the actions necessary to ensure effective
and safe processing of the endoscope and its accessories in the WD be followed, e.g. leak testing, any pre-
treatment, manual cleaning or disassembly, of the endoscope [see 8 k) 8)].
It shall be specified which of the pre-treatment steps, as listed in the endoscope’s processing instructions for
use, shall be performed in order to ensure effective and safe processing of the endoscope.
NOTE National guidelines can require certain pre-cleaning steps (e.g. brushing of endoscopes channels prior to
processing in a WD).
4.1.5 The value of any
...