ISO/DTS 18671

Test methodologies for assessing the compatibility of wet wipes and moist toilet tissue with the wastewater collection and treatment systems, and appropriate labelling

This document identifies test methodologies for assessing the compatibility with the wastewater system of wet wipes and moist toilet tissue, and it specifies appropriate labelling. It is applicable to disposable products designed for, marketed for or likely to be used in a bathroom. This document excludes: • dry toilet paper as defined and covered by other ISO documents. • chemical toilets or compost toilets that are not connected to sewer systems. • macerator and vacuum sewer systems • water soluble polymers

Méthodologies d'essai pour évaluer la compatibilité des lingettes humides et du papier hygiénique humide avec les systèmes de collecte et de traitement des eaux usées, et étiquetage approprié

General Information

• Status: Not Published
• ICS: 85.080.20 - Tissue paper
• 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: 5020 - FDIS ballot initiated: 2 months. Proof sent to secretariat
• Start Date: 30-Mar-2026
• Completion Date: 30-Mar-2026

Overview

ISO/DTS 18671 provides comprehensive test methodologies for assessing the compatibility of wet wipes and moist toilet tissue with wastewater collection and treatment systems. Developed by ISO/TC 224, this international standard outlines procedures for evaluating whether so-called "flushable" products can be safely disposed of via toilets without causing blockages, environmental impact, or operational issues in domestic plumbing, sewer networks, or wastewater treatment plants. The document also specifies appropriate labelling criteria to ensure consumers are informed of proper disposal methods.

This standard applies primarily to disposable bathroom products likely to be flushed. It excludes dry toilet paper, chemical or compost toilets not connected to sewer systems, macerator and vacuum sewer systems, and water soluble polymers, as these are covered by other regulations or present distinct technical challenges.

Key Topics

• Test Methodologies: ISO/DTS 18671 describes evaluation procedures for domestic plumbing, drainlines, wastewater transport, pumping stations, and treatment processes. Standardized tests such as toilet clearance, drainline clearance/disintegration, and household/municipal pump testing are included to simulate real-world usage and infrastructure conditions.

• System Compatibility: The standard emphasizes the importance of verifying that products do not obstruct toilets, household drainlines, or municipal sewer systems. Tests are designed to assess product disintegration and biodegradation to minimize the risks of sewer blockages, increased solid waste, and operational disruptions.

• Environmental Considerations: Assessments focus on the ability of wet wipes and moist tissue to biodegrade in aerobic and anaerobic wastewater treatment environments. Ensuring products do not persist or generate harmful residues is a critical criterion.

• Labelling Requirements: ISO/DTS 18671 details best practices for consumer labelling. This includes when to apply labelling, packaging location, size and design of symbols, and advisory text, all aimed at clear communication of correct disposal pathways-whether a product is "flushable" or not.

• Global Methodologies: The standard references several established national and international methodologies, including GD4 (INDA/EDANA), UK Water Industry Specification (WIS), Australian/New Zealand, Chinese, and IWSFG PAS standards, highlighting regional differences and the importance of using complete, non-interchangeable methods.

Applications

• Manufacturers of Wet Wipes and Moist Toilet Tissue: ISO/DTS 18671 provides a structured approach to testing product flushability, ensuring compliance and supporting claims made on product packaging.

• Wastewater Utility Operators and Planners: By setting out compatibility criteria, the standard helps protect collection system integrity and reduce maintenance costs associated with blockages or operational failures caused by inappropriate products being flushed.

• Retailers and Brand Owners: The standard’s labelling requirements assist in education and outreach, helping customers make informed choices and reducing negative impacts on the sewer system.

• Regulatory and Environmental Agencies: Adoption and reference to this standard supports formulation of effective policies and public health protection, while lowering environmental impact from improper disposal of consumer products.

Related Standards

• ISO 12625 series – Testing standards for tissue and tissue products
• ISO/TR 24524 – Technical report on key elements and operation of wastewater collection systems
• GD4 (INDA/EDANA Guidelines) – Guidelines for nonwoven product flushability (North America/Europe)
• IWSFG PAS 1-3 – Publicly available specifications for flushable products
• UNE 149002 (Spain) – National criteria for flushability
• AS/NZS 5328:2022 – Flushable products standard (Australia & New Zealand)
• GB/T 40181-2021 – Flushability test method (China)
• WIS 4-02-06 – UK Water Industry Specification for drain/sewer system compatibility

ISO/DTS 18671 is a critical standard for sustainable management of wet wipes and moist toilet tissue, supporting both product innovation and protection of water infrastructure. Compliance with this standard helps safeguard urban infrastructure, minimize environmental risk, and improve communication to end users.

Standards Content (Sample)

DRAFT
International
Standard
ISO/DIS 18671
ISO/TC 224
Test methodologies for assessing
Secretariat: AFNOR
products suitable to be flushed
Voting begins on:
down a toilet and appropriate
2024-11-12
labelling
Voting terminates on:
ICS: 85.080.20
2025-02-04
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.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
This document is circulated as received from the committee secretariat.
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
RECIPIENTS OF THIS DRAFT ARE INVITED
TO SUBMIT, WITH THEIR COMMENTS,
NOTIFICATION OF ANY RELEVANT PATENT
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Reference number
ISO/DIS 18671:2024(en)
DRAFT
ISO/DIS 18671:2024(en)
International
Standard
ISO/DIS 18671
ISO/TC 224
Test methodologies for assessing
Secretariat: AFNOR
products suitable to be flushed
Voting begins on:
down a toilet and appropriate
labelling
Voting terminates on:
ICS: 85.080.20
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.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2024
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
This document is circulated as received from the committee secretariat. BE CONSIDERED IN THE LIGHT OF THEIR
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
or ISO’s member body in the country of the requester.
NATIONAL REGULATIONS.
ISO copyright office
RECIPIENTS OF THIS DRAFT ARE INVITED
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TO SUBMIT, WITH THEIR COMMENTS,
CH-1214 Vernier, Geneva
NOTIFICATION OF ANY RELEVANT PATENT
Phone: [phone]
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 18671:2024(en)
ii
ISO/DIS 18671:2024(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Framework . 2
4.1 Context .2
4.1.1 General .2
4.2 Domestic plumbing and drainline systems .3
4.2.1 Toilets .3
4.2.2 Drainlines .3
4.3 Wastewater transport systems .4
4.3.1 General .4
4.3.2 Sewers .4
4.3.3 Pumping stations .4
4.4 Wastewater Treatment systems .5
4.4.1 General .5
4.4.2 Settling .5
4.5 Biodegradation/biodisintegration .5
4.6 Onsite domestic wastewater systems .5
4.7 Environment .5
5 Testing methodologies . 5
5.1 General .5
5.2 Domestic plumbing and drainline systems .7
5.2.1 General .7
5.2.2 Toilet clearance test .7
5.2.3 Drainlines .7
5.2.4 Household pump tests .7
5.3 Wastewater transport networks .8
5.3.1 General .8
5.3.2 Disintegration testing .8
5.3.3 Municipal Sewage Pump test.10
5.4 Wastewater Treatment systems .10
5.4.1 General .10
5.4.2 Settling .10
5.4.3 Biodegradation/biodisintegration tests .10
6 Labelling .11
6.1 General .11
6.2 When to apply labelling .11
6.3 Packaging .11
6.4 Location on the packaging . 12
6.5 Geometric shape and colour . 12
6.6 Size . 12
6.7 Advisory Text . 12
Annex A (informative) Examples of Labelling .13
Annex B (informative) Informative Summary of Current Test Methods . 14
Bibliography .25

iii
ISO/DIS 18671:2024(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 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 TC 224 WG 10.
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/DIS 18671:2024(en)
Introduction
Flushing of product that is incompatible with sewerage networks can contribute to
— blockages in home plumbing and smaller sewer pipes, and blockages in pumps,
— increased screening of solids for solid waste disposal
— increased burden for treatment processes both onsite and municipal with non-degradable materials
which can lead to further downstream environmental impacts.
— increased risk of sewer blockages at reduced sewer flows.
Consistent labelling and education to inform consumers of proper disposal of products which are flushed is
important to help reduce adverse effects on wastewater collection and treatment systems.
This document provides recommendations for
— labelling to be used with both flushable and non-flushable product packages in the absence of any local,
state, national labelling regulations.
— the use of any of five different available methodologies worldwide for assessing products that can be
flushed down the domestic toilet and subsequent labelling.
It is important to note that each of the methodologies are stand alone, and the individual methods are not
designed to be interchanged. They are outlined in the appendices, detailing where they are being used and
differences in testing approach enabling the reader to select whether a particular methodology is more
relevant to their geographical region.

v
DRAFT International Standard ISO/DIS 18671:2024(en)
Test methodologies for assessing products suitable to be
flushed down a toilet and appropriate labelling
1 Scope
This document identifies test methodologies for assessing the flushability of products that can be disposed
via the toilet, and it specifies appropriate labelling. It is applicable to disposable products designed for,
marketed for or likely to be used in a bathroom.
This document excludes:
— dry toilet paper as defined and covered by other ISO documents.
— chemical toilets or compost toilets that are not connected to sewer systems.
— macerator and vacuum sewer systems
— water soluble polymers
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 24513 and the following apply.
3.1
biodegradation
degradation due to the biological environment
[SOURCE: ISO/TR 13329:2012(en), 3.4 modified by the removal of Note 1]
3.2
disintegration
material breaking into small pieces in water under specified conditions
[SOURCE: ISO 12625-17:2021(en), 3.1, modified]
3.3
methodology
collection of standards, procedures and supporting methods that define the complete approach to the
development of a product or system
[SOURCE: ISO/IEC 21827:2008(en), 3.22]
3.4
mineralization
decomposition of organic matter or organic substances into carbon dioxide, water and the hydrides, oxides
or other mineral salts
[SOURCE: ISO 11074:2015, 3.3.19]

ISO/DIS 18671:2024(en)
3.5
persistence
existing or remaining in the same state for an indefinitely long time
[SOURCE: ISO TR 18307:2001]
3.6
plastic
solid material which contains, as an essential ingredient, one or more synthetic organic high polymers and
which is formed (shape) during either manufacture of the polymer or the fabrication into a finished product
by heat and/or pressure
Note 1 to entry: In different regions there are legal definitions of plastic(s). Users of this standard are advised to check
the definition of plastic in the geographical / jurisdictional region where products are marketed.
[SOURCE: ISO 13618: 2001, 3.12 modified – Note removed, and new note added.]
3.7
toilet paper
(id bathroom tissue, id bath tissue): tissue paper intended for sanitary use after using the toilet.
[SOURCE: ISO 12625-17:2021(en), 3.1, modified]
Note 1 to entry: for the purpose of this document, “dry toilet paper” is another word to designate “toilet paper” as
defined by the EN ISO 12625-1.
Note 2 to entry: products labelled as “moist toilet paper” are often made from nonwoven material and are not
considered as “toilet paper” for the purpose of this document.
3.8
transit time
sewer transit time (also referred to as sewer residence time, in-sewer travel time, or wastewater residence
time) refers to the amount of time a given volume of wastewater resides in a sewer system between a
designated beginning and end point (for example, a pumping station or treatment plant).
3.9
toilet (water closet - W/C)
fixed receptacle into which a person may urinate or defecate, typically consisting of a large bowl connected
to a cistern for flushing.
Note 1 to entry: Also known as a Water Closet (WS).
[SOURCE: ISO TR 24524:2019 3.7]
4 Framework
4.1 Context
4.1.1 General
This document is based on approaches within the following currently available national standards,
international guidelines and specifications which have been adopted in some regions.
— AS NZS 5328: 2022 Flushable Products (Australia)
— GB/T 40181-2021 Test method and evaluation for flushability of disposable sanitary nonwoven materials (China)
— INDA and EDANA, Code of Practice: Communicating Appropriate Disposal Pathways for Single Use Nonwoven
rd
Wet Wipes to Protect Wastewater Systems, 3 edition, March 2022.

ISO/DIS 18671:2024(en)
— INDA/EDANA Guidelines for Assessing the Flushability of Disposable Nonwoven Products with Plumbing and
Wastewater Infrastructure, Edition 4 (2018) – GD4.
— International Water Services Flushability Group Publicly Available Specifications (PAS) 1 to 3 (2020):
Criteria for recognition as a flushable product – PAS documents.
— Royal Decree establishing a framework for the definition of the requirements for biodegradability and
disintegratability of products designed to be disposed of in toilets – October 2015 (Belgium)
— UNE 149002: 2019 Acceptance Criteria for flushable products (Spain)
— Water UK Water Industry Specification, Fine to Flush: Specification for a testing methodology to determine
whether a product is suitable for disposal through a drain or sewer system, WIS 4-02-06 (November 2019),
Issue 1.2 – UK WIS.
Appendix B provides an overview of the various test methodologies in use, when they were published, their
relevance and the regions/countries where they are being applied. When selecting a particular methodology
described in Annex B it is important to follow that methodology as prescribed. Test methods from different
methodologies should not be interchanged. The key elements of a wastewater system to be considered in
test methods for evaluating products suitable for toilet disposal are described in ISO/TR 24524. The design,
operation and serviceability of sewerage facilities can vary widely from country to country.
The key elements are:
(a) toilets;
(b) drainlines (including domestic pumps);
(c) wastewater transport systems (including municipal pumps) and screening;
(d) treatment processes;
(e) environment
The wastewater system comprises elements (a) to (d). Material that enters wastewater
treatment plants can either be removed via degradation, integration into the semi-solid phase, volatilized
into gaseous form or released in the treated effluent discharged from the wastewater treatment plant to
receiving environments.
Products disposed into wastewater systems can also reach receiving environments without treatment. From
time to time, sewers overflow to the environment for a multitude of reasons. Given that products disposed
into wastewater systems have the potential to cause environmental harm if untreated, products should be
[1]
evaluated for environmental and treatment plant compatibility .
4.2 Domestic plumbing and drainline systems
4.2.1 Toilets
The purpose of a toilet is to dispose of human excreta (i.e. urine, menses, vomit and faeces) by using water to
flush it through a drainline to another location for disposal, thus maintaining a separation between humans
and their waste. Any product discharged via a toilet should not adversely affect the intended operation of
[2]
the toilet. The typical flush volume for new toilets varies from 2 L to 6 L .
4.2.2 Drainlines
Drainline design, configuration, construction and maintenance can impact the ability of waste to pass
through a drainline. Typically, material flushed from a toilet into a drainline moves along the drainline with
water from toilet flushing. Failure of flushed product to exit the drainline can result in blocked plumbing
within the property, blocked external drainage pipelines, the generation of foul odours or allow product

ISO/DIS 18671:2024(en)
to dry out and adhere to the pipe surface. Product intended to be discharged via a toilet should clear the
drainline and reach the sewer without adversely affecting the operation of the drainline.
4.3 Wastewater transport systems
4.3.1 General
The design, layout and configuration of wastewater transport systems vary among and within countries
due to various factors including regulation, population density, system age, geographic and topographic
features, and climatic conditions.
4.3.2 Sewers
4.3.2.1 Wastewater Network Hydraulics and Solids Transport
The purpose of the sewer is to receive discharges from drainlines and convey to wastewater treatment
systems. Flow in wastewater conveyance systems typically occurs via gravity flow, pumped flow, vacuum
pressure or a combination. Flow can be intermittent or continuous and is dependent on the sewer design,
wastewater flow conditions influenced by rainfall and/or peak discharge usage. In small diameter pipes
(less than 225 mm), there is an elevated risk that products introduced into the sewer system can become
snagged on pipe imperfections or tree roots, and result in pipe blockages.
4.3.2.2 Wastewater Transport Network Velocity
Wastewater velocities vary significantly as a result of a range of factors including sewer design, climatic
conditions, topography and volume. In general, sewers are designed to achieve a velocity sufficient to
transport solids to prevent deposition and decomposition in the sewer. To prevent the settlement of
[3]
wastewater solids, the velocity in a sewer should meet local minimum flow requirements .
4.3.2.3 Transit Time
Surveys of sewer transit times indicate the typical duration to the first screen or pump is between 30 minutes
and 6 hours, although it can be less than 10 minutes for densified residential areas and it can reach several
[4] [5] [6] [7]
days. , , , Transit time should be considered when selecting tests methodologies. Local conditions can
require a higher minimum cross-sectional velocity value or a minimum sewer slope value.
4.3.2.4 Temperature
The temperature of the wastewater can vary depending on geographic location and season. It can typically
[8]
range from 5 °C to 30 °C .
4.3.3 Pumping stations
Pumps are commonly used to facilitate wastewater transport where this cannot be achieved by gravity
alone. They are typically utilized within the transport system from the point of discharge from the customer
property to the nearest point where gravity flow is possible or to the treatment plant. Screens or grinders
can be installed ahead of the pumps or other downstream infrastructure, including overflow outlets, and
immediately before the influent point of the treatment system to protect equipment from becoming blocked.
Products greater than a certain size can foul screens, resulting in an elevated load of solid waste to landfill,
[9]
increased maintenance or potential blockages leading to sewer overflows and flooding .
Solids transported in sewers can accumulate and cause pump malfunction in pumping stations before
reaching wastewater treatment plants. Such events are observed worldwide.

ISO/DIS 18671:2024(en)
4.4 Wastewater Treatment systems
4.4.1 General
A product that enters a wastewater treatment plant should not unduly affect the ability of that plant to meet
legislated or licence conditions. It is important that the effluent discharged from wastewater treatment
[10]
plants does not pose an increased environmental risk .
4.4.2 Settling
The majority of solids that enter a wastewater treatment plant are removed through initial screening and
subsequent settling throughout the treatment process. The rate of settling within a wastewater treatment
plant is measured by the settling velocity. The settling rate of a product is affected by particle size and
density, along with system design, operation and capacity. A settling test should be used to evaluate the
[11]
settling rate for products .
4.5 Biodegradation/biodisintegration
The purpose of wastewater treatment is to separate and treat the solids and clean the incoming wastewater
to a level suitable for discharge or reuse. Organic wastewater solids are typically broken down biologically
using aerobic or anaerobic digestion processes. The dewatered digested sludge solids (also called biosolids)
can then be incinerated, landfilled, or land applied.
To evaluate if a product is compatible with biological wastewater treatment process and can be fully treated
such that no product be recognizable in effluent leaving municipal wastewater treatment systems or in the
[5]
post-treatment products of treatment sludges, laboratory tests should be utilized to evaluate the potential
of products to break down biologically under aerobic and anaerobic conditions.
These tests can also be utilized to determine if a product contains materials that do not degrade biologically
in aerobic or anaerobic conditions and are therefore likely to be discharged in the wastewater effluent
or persist in biosolids which could be subsequently land applied, or if discharged directly to a receiving
environment.
4.6 Onsite domestic wastewater systems
On-site domestic wastewater systems (ODWS) are widely used throughout the world to collect, treat,
discharge, disperse or reuse domestic wastewater in areas where centralized sewerage systems are not
viable or not currently available. An ODWS is often a self- contained unit designed to collect, treat and
discharge, disperse or reuse wastewater. The testing protocols proposed in this document do not distinguish
between ODWS and centralized treatment systems. However, methodologies take into account aspects of
different types of ODWS, including more basic systems.
For ODWS, the toilet and drainline test, the domestic pump test, the settling test and biodisintegration tests
should be utilized where possible to evaluate if the product can be transported with wastewater solids
through the toilet and downstream pipework and domestic pumps if the product will settle inside the tank
and if it will be mineralized.
4.7 Environment
For flushable products, consideration should be given to environmental safety, including assessment of
toxicity, bioaccumulation and persistence of their components.
5 Testing methodologies
5.1 General
The current methodologies for evaluating products for compatibility with wastewater systems follow
two predominant testing methodologies. The two primary models are GD4 and the UK Water Industry

ISO/DIS 18671:2024(en)
specification (UK WIS). The GD4 model has been utilized with several variations including the removal
and modification of test parameters and pass/fail criteria. The details of these modifications are outlined
in this document. The pass-fail criteria for each of those referenced testing regimes can be found in the
documents listed in the bibliography and are summarized in Annex B. Note that each testing methodology is
independent and should be used in its entirety.
When adopting standards, it is necessary to understand the sewage facilities of the country in question and
select standards that are compatible with the sewage facilities. This document provides information for the
appropriate test methodology for each country.f
The following flow chart outlines the approach for determining whether a product is in scope for this
document and associated labelling.
NOTE The relevant test methodologies are outlined in Annex B.1.
Current testing methodologies available have key similarities. This document identifies their differences
and options for addressing them.
Both GD4 and the UK WIS evaluate performance of products in infrastructure from the toilet through
residential plumbing, wastewater transport infrastructure and wastewater treatment. The local standards
developed for countries including Belgium, Spain, China, Australia, and New Zealand are all based on GD4.
The IWSFG is also based on GD4. Note that several of these have modifications for operating conditions
and pass/fail criteria. The reason for these modifications is to address different perspectives regarding
protection of, and product compatibility with, wastewater systems.

ISO/DIS 18671:2024(en)
5.2 Domestic plumbing and drainline systems
5.2.1 General
A product discharged via a toilet should not adversely affect the intended operation of the drainline or sewer
system and should not impact drainline function, whether or not it has snagged on imperfections or other
impediments within the pipe. To account for local conditions in the UK the UK WIS should be used when
assessing product as suitable for toilet flushing in the UK, coupled with the Drainline Disintegration Test.
GD4 includes a Household Pump Test in addition to the Toilet and Drainline Clearance Test. The Household
Pump Test is not necessarily part of local requirements based on GD4. When selecting a methodology to use,
it should be adopted in full. The methodologies were designed to be stand alone. The tests are not designed
to be mixed and matched as needed.
Details of the test methods currently in use for domestic plumbing and drainline systems are provided in
Appendix B.2 and B.3.
5.2.2 Toilet clearance test
The product should not block or allow the toilet to surcharge (overload) or overflow. The purpose of toilet
clearance testing is to assess that products do not adversely affect toilet operation. GD4 and its variants
integrate the drainline clearance test with the toilet bowl clearance test whereas the UK WIS separates toilet
testing from the drainline clearance test. For GD4 the material flushed down the toilet includes simulated
faecal material, dry toilet paper and the tested product to simulate user behaviour (4 people), whereas the
UK WIS uses only the tested product alone.
The GD4 method allows the single use of a plunger, wherein one replicate is allowed to be plunged, while
modifications to this have been made in methodologies that incorporate the GD4 Toilet and Drainline test.
5.2.3 Drainlines
5.2.3.1 Drainline clearance test
A drainline clearance test should be used to ascertain that a product exits the drainline without causing
backup of water and materials. The intent of the drainline clearance tests of GD4 and the UK WIS are similar,
i.e. that product moves along the drainline and exits within a certain number of flushes. The GD4 test
methodology is adjustable for different toilet flush volumes and to account for the slope of the drainline. The
details of typical international variations for these parameters are outlined in TR 24524.
GD4 assesses the movement of material down the drainline using a calculation called the Centre of Mass.
This establishes that the material is moving down the drainline, accounting for pieces if the material starts
to separate as it moves. The Centre of Mass is the weighted average position of the material (mass weighted
center). It has been replaced by Centre of Movement in AS/NZS 5238, which is the average position of the
material. The material flushed down the drainline includes simulated faecal material, dry toilet paper and
the tested product in a given sequence to simulate user behaviour (4 people) using the toilet.
5.2.3.2 Drainline Disintegration test
In order to assess if a product is capable of disintegrating sufficiently, to an extent that minimises risk
of blockage to a pipe or pumps, as it passes through the drainline, the UK has developed a drainline
disintegration test. This test has not been adopted elsewhere as the other tests associated with the drainline
in alternative test methods address this concern.
5.2.4 Household pump tests
A household pump test should be used to assess the compatibility of a product with household sewage pump
systems to assess that the product does not clog, accumulate within or otherwise interfere with normal
system operation. The test seeks to simulate the conditions of operation for a household pump by using
a typical household wastewater pump (Appendix B.4) in a container connected to a discharge pipe under
laboratory conditions.
ISO/DIS 18671:2024(en)
5.3 Wastewater transport networks
5.3.1 General
It is necessary to assess the compatibility of a product with pumping systems or downstream pipework. For
this purpose, a disintegration test is included in all test methodologies and supplemented by a municipal
pump test in GD4 and some of its variants. Details of the test methods currently in use are provided in
Appendix B.5.
5.3.2 Disintegration testing
A disintegration test should be used to assess the compatibility of products with sewer networks. There are
two tests available, the Slosh Box Disintegration test and the UK WIS Sewer System Shake Flask test. Both
test methodologies have been developed through laboratory simulation of forces similar to sewer networks
and observation of the relative disintegration of product within artificial and live sewer networks.
The degree of disintegration required for sewer network compatibility is not fully agreed by experts. This is
reflected in the test methodologies.
Variations to the disintegration test parameters have been developed based on laboratory testing within
different regions. A detailed description of the approach and considerations for differences in the test
parameters are provided below. These considerations should be taken into account when selecting a
methodology.
There are six tests currently referenced by national and international standards, guidelines and
specifications relating to the characterization of physical disintegration to determine if a product is suitable
for disposal via toilet flushing (Appendix B.5):
1. Belgium – Royal Belgian Decree (2015) – Rapid Mechanical Disintegration Test. Based on INDA/EDANA
Guidance Document, Third Edition (GD3) FG502 Slosh Box
2. INDA/EDANA Guidance Document, Fourth Edition (GD4) FG502.R1(18) (2017) Slosh Box
Disintegration Test
a. Note: Method included in Spanish Standard UNE 149002 Acceptance criteria for products that can
be flushed down the toilet
b. Note: Method included in Chinese Standard GB/T 40181-2021 Test method and evaluation for
flushability of disposable sanitary nonwoven materials (China)
3. IWSFG Publicly Available Specification (PAS) 3: 2020 Disintegration Test Methods – Slosh box
4. WIS 4-02-06 Issue 1.2 Appendix C (2019) Disintegration in the Drainline Test
5. WIS 4-02-06 Issue 1.2 Appendix E (2019) Disintegration in the Sewer Test
6. Australian / New Zealand Standard (2022)– Flushable products (slosh box disintegration test)
Considerations in applying these test methods are:
1) The above-referenced versions of the slosh box disintegration test contain multiple independent variables,
the setpoints of which significantly influence test outcomes (refer Appendix B.5 for details):
test duration (measured in minutes or hours)
(a) speed (the speed of the reciprocation of the slosh box or the speed of the rotation of the shake flask,
measured in revolutions per minute [RPM])
(b) volume of media (measured in litres [L])

ISO/DIS 18671:2024(en)
(c) sieve opening size (the size of the sieve utilized for sample recovery after testing, measured in
millimeters [mm]),
(d) pre-treatment (rinsing of samples, or static conditioning of a sample in open air prior to testing,
measured in minutes [min])
(e) temperature (measured in degrees Celsius [C]).
2) The interaction of the independent variables (identified as “Parameter” in Table 5.3a) directly impacts
test outcomes and variability.
Table 5.3 — a General impact of individual test parameters
Parameter Impacts
Inclusion of a pre-conditioning step that introduces additional time for a product to
Preconditioning
lose strength prior to testing.
Speed Lower speed introduces less turbulence during testing.
A shorter test duration reduces the amount of force experienced by the sample, which
Duration
is directly related to time under testing.
A larger volume of water reduces the amount of turbulence generated during each
Media Volume
articulation
Temperature A lower temperature can reduce the amount of sample disintegration.
A small sieve opening size requires the sample to reach smaller dimensions in order to
Sieve opening size
pass through the sieve
The transit time varies depending on the wastewater network design. Therefore, it is necessary to consider
transit time and other factors when applying the disintegration test.
3) When considering the slosh box disintegration tests for evaluating physical disintegration, a comparison
between versions indicates the IWSFG version will produce less disintegration than the AUS/NZ version,
than the INDA/EDANA GD4 version, than the INDA/EDANA GD3 version.
As noted in 5.3.2 subpart 2, the interaction of independent variables can be significant. The screening tests
developed to date are intended to evaluate the disintegration potential of products in a repeatable manner
under mechanical agitation in water that is intended to approximate conditions in a specific portion of sewer
networks.
4) The UK WIS Disintegration in the Sewer System shake flask tests differs from the slosh box-based
disintegration tests in terms of testing equipment, parameters and procedures (Appendix B.5). The WIS
shake flasks tests contain multiple independent variables, the setpoints of which significantly influence
test outcomes:
(a) test duration (measured in minutes or hours)
(b) speed (the speed of the reciprocation of the slosh box or the speed of the rotation of the shake flask,
measured in revolutions per minute [RPM])
(c) perforated plate sieve opening size (the size of the sieve utilized for sample recovery after testing,
measured in millimeters [mm])
When considering the shake flask disintegration tests for evaluating physical disintegration, a comparison
between versions indicates the UK WIS Appendix C version will produce less disintegration than the
Appendix E version. Both the test duration and sieve endpoint are intended to reflect conditions within the
wastewater transport systems across the United Kingdom.
The interaction of independent variables within and among the disintegration tests can be significant.
As designed, the screening tests developed to date are intended to evaluate the disintegration potential
of products in a repeatable manner under mechanical agitation in water that is intended to approximate
conditions in a specific portion of sewer networks.

ISO/DIS 18671:2024(en)
5.3.3 Municipal Sewage Pump test
A municipal sewage pump test should be used to determine the compatibility of products with municipal
sewage pumping systems. The test employs a small municipal pump typically used in municipal wastewater
systems as a realistic worst-case scenario. The municipal sewage pump test measures pump power increases
and is not included within all methodologies.
5.4 Wastewater Treatment systems
5.4.1 General
The intent of tests for evaluating compatibility of products with wastewater treatment systems are to assess
that the product is not buoyant and can settle within a short period of time and not resuspend into the water
column. In this case the settling test should be used. The second suite of tests are screening tests to assess
the ability of the product to biologically degrade under aerobic or anaerobic conditions found in onsite and
municipal wastewater treatment systems. In this case biodegradation/ biodisintegration test should be used.
5.4.2 Settling
This test is relatively consistent between the GD4 (including all variations) and the UK WIS test methodologies
(Appendix B.6). Noting that the UK WIS evaluates if product components will settle, where GD4 evaluates
the rate of settling for the product.
5.4.3 Biodegradation/biodisintegration tests
5.4.3.1 General
Testing should assess the biodegradation or persistence of products in receiving environments.
Biodegradation or biodisintegration tests can be used to evaluate compatibility with wastewater treatment
and environmental persistence. The use of the product fibre compositional analysis or a manufacturer
attestation can be considered to avoid plastic content in the p
...

FINAL DRAFT
Technical
Specification
ISO/TC 224
Test methodologies for assessing
Secretariat: AFNOR
the compatibility of wet wipes
Voting begins on:
and moist toilet tissue with
2026-03-30
the wastewater collection and
Voting terminates on:
treatment systems, and appropriate
2026-05-25
labelling
Méthodologies d'essai pour évaluer la compatibilité des lingettes
humides et du papier hygiénique humide avec les systèmes de
collecte et de traitement des eaux usées, et étiquetage approprié
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
TO BECOME STAN DARDS TO WHICH REFERENCE MAY BE
MADE IN NATIONAL REGULATIONS.
Reference number
FINAL DRAFT
Technical
Specification
ISO/TC 224
Test methodologies for assessing
Secretariat: AFNOR
the compatibility of wet wipes
Voting begins on:
and moist toilet tissue with
the wastewater collection and
Voting terminates on:
treatment systems, and appropriate
labelling
Méthodologies d'essai pour évaluer la compatibilité des lingettes
humides et du papier hygiénique humide avec les systèmes de
collecte et de traitement des eaux usées, et étiquetage approprié
RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT,
WITH THEIR COMMENTS, NOTIFICATION OF ANY
RELEVANT PATENT RIGHTS OF WHICH THEY ARE AWARE
AND TO PROVIDE SUPPOR TING DOCUMENTATION.
© ISO 2026
IN ADDITION TO THEIR EVALUATION AS
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO­
LOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL
or ISO’s member body in the country of the requester.
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Published in Switzerland Reference number
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Framework . 3
4.1 Context .3
4.2 Domestic plumbing and drainline systems .4
4.2.1 Toilets .4
4.2.2 Drainlines .4
4.3 Wastewater transport systems .4
4.3.1 General .4
4.3.2 Sewers .4
4.3.3 Pumping stations .5
4.4 Wastewater treatment systems .5
4.4.1 General .5
4.4.2 Settling .5
4.5 Biodegradation and biodisintegration .5
4.6 On-site domestic wastewater systems .6
4.7 Environment .6
5 Testing methodologies . 6
5.1 General .6
5.2 Domestic plumbing and drainline systems .7
5.2.1 General .7
5.2.2 Toilet clearance test .8
5.2.3 Drainlines .8
5.2.4 Household pump test .8
5.3 Wastewater transport networks .8
5.3.1 General .8
5.3.2 Disintegration testing methods .9
5.3.3 Disintegration testing method considerations .9
5.3.4 Municipal sewage pump test .10
5.4 Wastewater treatment systems .10
5.4.1 General .10
5.4.2 Settling .10
5.4.3 Biodegradation and biodisintegration tests .11
6 Labelling .12
6.1 General . 12
6.2 When to apply labelling . 12
6.3 Packaging . 12
6.4 Location on the packaging . 12
6.5 Geometric shape and colour . 13
6.6 Size . 13
6.7 Advisory text . 13
Annex A (informative) Examples of labelling . 14
Annex B (informative) Summary of current test methods .15
Bibliography .25

iii
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 224, Drinking water, wastewater and
stormwater systems and services.
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
Introduction
Flushing of products that are incompatible with sewerage networks can contribute to:
— blockages in home plumbing and smaller sewer pipes, and blockages in pumps;
— increased screening of solids for solid waste disposal;
— increased burden for treatment processes both on-site and at the municipal level, with non-degradable
materials which can lead to further downstream environmental impacts;
— increased risk of sewer blockages at reduced sewer flows.
Consistent labelling and education to inform consumers of proper disposal of products is important to
help reduce adverse effects on wastewater collection and treatment systems. Application of this document
presupposes that not only the producers but also all the concerned parties about export, retail or
consumption are aware of the legislation and regulations pertaining to wet wipes and moist toilet tissues.
This document provides recommendations regarding:
— labelling and the use of a symbol to be used with non-flushable product packages indicating incompatibility
with the wastewater system;
If a product is compatible with a wastewater collection and treatment system the producer may use
a suitable symbol conforming with relevant local or national standards, or in compliance with legal
requirements of the targeted country or region.
— the use of any of five different available methodologies worldwide for assessing product compatibility
with the wastewater collection and treatment system and subsequent labelling.
This document describes currently published test methodologies for assessing compatibility of products
with wastewater networks. Each methodology comprises different methods that must be used to determine
wastewater network compatibility. It is important to note that the methodologies are stand alone, and the
individual methods are not designed to be interchanged. They are outlined in Annex B, detailing where
they are being used and differences in testing approach, enabling the reader to select whether a particular
methodology is more relevant to their geographical region.

v
FINAL DRAFT Technical Specification ISO/DTS 18671:2026(en)
Test methodologies for assessing the compatibility of wet
wipes and moist toilet tissue with the wastewater collection
and treatment systems, and appropriate labelling
1 Scope
This document provides test methodologies for assessing the compatibility of wet wipes and moist toilet
tissue with the wastewater collection and treatment systems, and it specifies appropriate labelling for
products deemed incompatible. The products that this document is applicable for are wet wipes and moist
toilet tissue.
This document does not cover:
— toilet paper as defined and covered by other ISO documents;
— chemical toilets or compost toilets that are not connected to sewer systems;
— macerator and vacuum sewer systems;
— water soluble polymers.
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, Service activities relating to drinking water supply, wastewater and stormwater systems —
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 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
biodegradation
degradation due to the biological environment
[SOURCE: ISO/TR 19057:2017, 3.2, modified — Note 1 to entry was removed.]
3.2
disintegration
breaking of material into small pieces in water under specified conditions
[SOURCE: ISO 12625-17:2021, 3.1, modified — “process that is characterized by a material breaking” was
changed to “breaking of material”.]

3.3
methodology
collection of standards, procedures and supporting methods that define the complete approach to the
development of a product or system
[SOURCE: ISO/IEC 21827:2008, 3.22]
3.4
mineralization
decomposition of organic matter or organic substances into carbon dioxide, water and the hydrides, oxides
or other mineral salts
[SOURCE: ISO 11074:2025, 3.3.19, modified — “final stage of the biodegradation” was changed to
“decomposition”.]
3.5
moist toilet tissue
moist toilet paper
prewetted nonwoven material intended for sanitary use after using the toilet
Note 1 to entry: Products labelled as “moist toilet paper” are made from nonwoven material and are not considered as
“toilet paper” for the purpose of this document.
[SOURCE: ISO 12625-1:2019, 3.60, modified — The term was changed from “toilet paper” to “moist toilet
tissue”; in the definition, “tissue paper” was changed to “prewetted nonwoven material”.]
3.6
persistent
existing or remaining in the same state for an indefinitely long time
[SOURCE: ISO/TR 18307:2001, 3.111, modified — The admitted terms “persistence” and “enduring” were
removed.]
3.7
plastic
solid material which contains, as an essential ingredient, one or more high molecular mass polymers and
which is formed (shaped) during either manufacture of the polymer or the fabrication into a finished product
by either heat or pressure, or both
Note 1 to entry: In different regions there are legal definitions of plastic(s). Users of this document are advised to
check the definition of plastic in the geographical or jurisdictional region where products are marketed.
[SOURCE: ISO 21070:2017, 3.2.11 modified — The original Notes to entry were removed, and a new note was
added.]
3.8
toilet paper
bathroom tissue
bath tissue
dry toilet paper
tissue paper intended for sanitary use after using the toilet
Note 1 to entry: Products labelled as “moist toilet paper” are often made from nonwoven material and are not
considered as “toilet paper” for the purpose of this document.
[SOURCE: ISO 12625-1:2019, 3.60, modified — In the note to entry, “are not in the scope of this document”
was changed to “ are not considered ‘toilet paper’ for the purpose of this document”.]

3.9
transit time
sewer residence time
in-sewer travel time
wastewater residence time
amount of time a given volume of wastewater resides in a sewer system between a designated beginning
and end point
Note 1 to entry: Sewer systems include pumping stations and treatment plants.
3.10
toilet
water closet
WC
fixed receptacle into which a person may urinate or defecate, typically consisting of a large bowl connected
to a cistern for flushing
[SOURCE: ISO/TR 24524:2019, 3.7, modified — “water closet” and “WC” were added as admitted terms.]
3.11
wet wipe
small piece of premoistened or prewetted material which is conceived, designed and placed on the market
for single-use (disposable) and intended for personal care or domestic use
Note 1 to entry: Personal care is intended to be used for hygiene purposes, these include cleansing and caring of skin
of both human adults and babies e.g. cosmetics, baby wipes, intimate care wipes.
Note 2 to entry: A domestic use wet wipe is intended to be used in domestic premises. These include wet wipes used
for household cleaning purposes, e.g. wipes used to clean.
Note 3 to entry: Prewetted wipes typically contain an impregnation liquid which has been added to the wipe before it
is placed on the market.
Note 4 to entry: Adapted from Reference [11].
4 Framework
4.1 Context
References [9] to [20] were the basis for drafting this document. These documents are current national
standards, international guidelines and specifications which have been adopted in some regions.
Table B.1 provides an overview of the various test methodologies in use, when they were published,
their relevance and the regions or countries where they are being applied. When selecting a particular
methodology described in Annex B, based on the aspects outlined in this document, users should follow the
methodology as prescribed. Test methods from different methodologies should not be interchanged. The key
elements of a wastewater system to be considered in test methods for evaluating products suitable for toilet
disposal are described in ISO/TR 24524. The design, operation and serviceability of sewerage facilities can
vary widely from country to country.
The key elements are:
a) toilets;
b) drainlines (including domestic pumps);
c) wastewater transport systems (including municipal pumps) and screening systems;
d) treatment processes;
e) environment.
The wastewater system comprises elements (a) to (d). Material that enters wastewater treatment plants can
either be removed via degradation, integration into the semi-solid phase, volatilized into gaseous form or
released in the treated effluent discharged from the wastewater treatment plant to receiving environments.
Products disposed into wastewater systems can also reach receiving environments without treatment. From
time to time, sewers overflow to the environment for a multitude of reasons. Given that products disposed
into wastewater systems have the potential to cause environmental harm if untreated, products should be
[7]
evaluated for environmental and treatment plant compatibility.
4.2 Domestic plumbing and drainline systems
4.2.1 Toilets
The purpose of a toilet is to dispose of human excreta (i.e. urine, menses, vomit and faeces) by using water to
flush it through a drainline to another location for disposal, thus maintaining a separation between humans
and their waste. Any product discharged via a toilet should not adversely affect the intended operation of
[7]
the toilet. The typical flush volume for new toilets varies from 2 l to 6 l.
4.2.2 Drainlines
Drainline design, configuration, construction and maintenance can impact the ability of waste to pass
through a drainline. Typically, material flushed from a toilet into a drainline moves along the drainline with
water from toilet flushing. Failure of flushed product to exit the drainline can result in blocked plumbing
within the property, blocked external drainage pipelines, the generation of foul odours or the product
drying out and adhering to the pipe surface. Product intended to be discharged via a toilet should clear the
drainline and reach the sewer without adversely affecting the operation of the drainline.
4.3 Wastewater transport systems
4.3.1 General
The design, layout and configuration of wastewater transport systems vary among and within countries
due to various factors including regulation, population density, system age, geographic and topographic
features, and climatic conditions.
4.3.2 Sewers
4.3.2.1 Wastewater network hydraulics and solids transport
The purpose of the sewer is to receive discharges from drainlines and convey to wastewater treatment
systems. Flow in wastewater conveyance systems typically occurs via gravity flow, pumped flow, vacuum
pressure or a combination of these. Flow can be intermittent or continuous and is dependent on the sewer
design, wastewater flow conditions influenced by either rainfall or peak discharge usage, or both. In small
diameter pipes (less than 225 mm), there is an elevated risk that products introduced into the sewer system
can become snagged on pipe imperfections or tree roots, thus resulting in pipe blockages.
4.3.2.2 Wastewater transport network velocity
Wastewater velocities vary significantly as a result of a range of factors including sewer design, climatic
conditions, topography and volume. In general, sewers are designed to achieve a velocity sufficient to
[14]
transport solids to prevent deposition and decomposition in the sewer.
4.3.2.3 Transit time
Surveys of sewer transit times indicate the typical duration to the first screen or pump is between 30 minutes
and 6 hours, although it can be less than 10 minutes for densified residential areas and it can reach several

[15][23][24][25]
days. Transit time should be considered when selecting tests methodologies. Local conditions
can require a higher minimum cross-sectional velocity value or a minimum sewer slope value.
4.3.2.4 Temperature
The temperature of the wastewater can vary depending on geographic location and season. It can typically
[7]
range from 5 °C to 30 °C.
4.3.3 Pumping stations
Pumps are commonly used to facilitate wastewater transport where this cannot be achieved by gravity
alone. They are typically utilized within the transport system from the point of discharge from the customer
property to the nearest point where gravity flow is possible or to the treatment plant. Screens or grinders
can be installed ahead of the pumps or other downstream infrastructure, including overflow outlets, and
immediately before the influent point of the treatment system to protect equipment from becoming blocked.
Products greater than a certain size can foul screens, resulting in an elevated load of solid waste to landfill,
[7]
increased maintenance or potential blockages leading to sewer overflows and flooding.
Solids transported in sewers can accumulate and cause pump malfunction in pumping stations before
reaching wastewater treatment plants. Such events are observed worldwide.
4.4 Wastewater treatment systems
4.4.1 General
A product that enters a wastewater treatment plant should not unduly affect the ability of that plant to meet
legislated or licence conditions, and should not result in additional operational costs, nor adversely impact
the environment. The effluent discharged from wastewater treatment plants should not pose an increased
[7]
environmental risk.
4.4.2 Settling
The majority of solids that enter a wastewater treatment plant are removed through initial screening and
subsequent settling throughout the treatment process. The rate of settling within a wastewater treatment
plant is measured by the settling velocity. The settling rate of a product is affected by particle size and
density, along with system design, operation and capacity. A settling test should be used to evaluate the
[7]
settling rate for products.
4.5 Biodegradation and biodisintegration
The purpose of wastewater treatment is to separate and treat the solids and clean the incoming wastewater
to a level suitable for discharge or reuse. Organic wastewater solids are typically broken down biologically
using aerobic or anaerobic digestion processes. The dewatered digested sludge solids (also called biosolids)
can then be incinerated, landfilled or applied to the land.
To evaluate if a product is compatible with biological wastewater treatment process and can be fully treated
such that no product is recognizable in the effluent leaving municipal wastewater treatment systems or
[23]
in the post-treatment products of treatment sludges, laboratory tests should be utilized to evaluate the
potential of products to break down biologically under aerobic and anaerobic conditions.
These tests can also be utilized to determine if a product contains materials that do not degrade biologically
in aerobic or anaerobic conditions and are therefore likely to be discharged in the wastewater effluent or
persist in biosolids which could be subsequently applied to the land, or discharged directly to a receiving
environment.
4.6 On-site domestic wastewater systems
On-site domestic wastewater systems (ODWS) are widely used throughout the world to collect, treat,
discharge, disperse or reuse domestic wastewater in areas where centralized sewerage systems are not
viable or not currently available. An ODWS is often a self-contained unit designed to collect, treat and
discharge, disperse or reuse wastewater. The testing protocols proposed in this document do not distinguish
between ODWS and centralized treatment systems. However, methodologies take into account aspects of
different types of ODWS, including more basic systems.
For ODWS, a methodology that includes a toilet and drainline test, a domestic pump test, a settling test and
anaerobic and aerobic biodisintegration tests should be utilized to evaluate if the product can be transported
with wastewater solids through the toilet and downstream pipework and domestic pumps, if the product
will settle inside the tank, and if it will be mineralized.
4.7 Environment
For products covered by the scope of this document, consideration should be given to environmental safety,
including assessment of toxicity, bioaccumulation and persistence of their components.
5 Testing methodologies
5.1 General
Evaluation of products for compatibility with wastewater systems follow two predominant testing
[18] [24] [18]
methodologies. The two primary models are GD4 and the UK WIS . The GD4 model has been utilized
with several variations including the removal and modification of test parameters and pass or fail criteria.
The details of these modifications are outlined in this document. The pass-fail criteria for each of those
referenced testing regimes can be found in the documents listed in the bibliography and are summarized
in Annex B. When selecting a methodology to use, it should be adopted in full. The methodologies were
designed to be stand alone. The tests are not designed to be interchanged.
When adopting a methodology for a country or region it is important to understand the sewage facilities of
the country in question and select a methodology that is compatible with those assets.
Figure 1 outlines the approach for determining whether wet wipes and moist toilet tissue are in scope for
this document and the associated labelling.

Figure 1 — Flowchart with steps for assessing the compatibility of wet wipes and moist toilet tissue
with the wastewater collection and treatment systems, and to determine appropriate labelling
NOTE The relevant test methodologies are outlined in Table B.1.
Current available testing methodologies have key similarities. This document identifies their differences
and options for applying them.
[18] [24]
Both GD4 and the UK WIS evaluate performance of products in infrastructure from the toilet through
residential plumbing, wastewater transport infrastructure and wastewater treatment. The local standards
[18]
developed for countries including Belgium, Spain, China, Australia, and New Zealand are all based on GD4.
[18]
The IWSFG is also based on GD4. Several of these have modifications for operating conditions and pass or
fail criteria. The reason for these modifications is to address different perspectives regarding protection of,
and product compatibility with, wastewater systems.
5.2 Domestic plumbing and drainline systems
5.2.1 General
A product discharged via a toilet should not adversely affect the intended operation of the drainline or
sewerage system. Details of the test methods currently in use for domestic plumbing and drainline systems
are provided in Tables B.2 and B.3.

5.2.2 Toilet clearance test
The product should not block or allow the toilet to surcharge (overload) or overflow. The purpose of toilet
[18]
clearance testing is to assess that products do not adversely affect toilet operation. GD4 and its variants
[24]
integrate the drainline clearance test with the toilet bowl clearance test whereas the UK WIS separates
[18]
toilet testing from the drainline clearance test. For GD4 the material flushed down the toilet includes
simulated faecal material, toilet paper and the tested product to simulate user behaviour (4 people), whereas
[24]
the UK WIS uses only the tested product alone.
[18]
The GD4 method allows the single use of a plunger, wherein one replicate is allowed to be plunged, while
[18]
modifications to this have been made in methodologies that incorporate the GD4 toilet and drainline test.
5.2.3 Drainlines
5.2.3.1 Drainline clearance test
A drainline clearance test should be used to confirm that a product exits the drainline without causing
[18] [24]
backup of water and materials. The intent of the drainline clearance tests of GD4 and the UK WIS are
[18]
similar, i.e. that product moves along the drainline and exits within a certain number of flushes. The GD4
test methodology is adjustable for different toilet flush volumes and to account for the slope of the drainline.
The details of typical international variations for these parameters are outlined in ISO/TR 24524.
[18]
GD4 assesses the movement of material down the drainline using a calculation called the centre of mass.
This establishes that the material is moving down the drainline, accounting for pieces if the material starts
to separate as it moves. The centre of mass is the weighted average position of the material (mass weighted
[9]
centre). It has been replaced by centre of movement in AS/NZS 5328, which is the average position of the
material. The material flushed down the drainline includes simulated faecal material, toilet paper and the
tested product in a given sequence to simulate the behaviour of users (4 people) using the toilet.
5.2.3.2 Drainline disintegration test
In order to assess if a product is capable of disintegrating sufficiently, to an extent that minimises risk
of blockage to a pipe or pumps, as it passes through the drainline, the UK has developed a drainline
disintegration test. This test has not been adopted elsewhere as the tests associated with the disintegration
in alternative test methods address this concern.
5.2.4 Household pump test
[18]
GD4 includes a household pump test in addition to the toilet and drainline clearance test. The household
[18]
pump test is not necessarily part of local requirements based on GD4. A household pump test (see
Clause B.2) should be used to assess the compatibility of a product with household sewage pump systems
to assess that the product does not clog, accumulate within or otherwise interfere with normal system
operation. The test seeks to simulate the conditions of operation for a household pump by using a typical
household wastewater pump (Table B.2) in a container connected to a discharge pipe under laboratory
conditions.
5.3 Wastewater transport networks
5.3.1 General
Disintegration is a primary test used to assess the compatibility of a product with wastewater transport
systems including pumping systems and downstream pipework. For this purpose, a disintegration test is
[18]
included in all test methodologies and supplemented by a municipal pump test in GD4 and some of its
variants. Details of the test methods currently in use are provided in Table B.5.

5.3.2 Disintegration testing methods
[24]
There are two tests available, the slosh box disintegration test and the UK WIS sewer system shake flask
test. Both test methodologies have been developed through laboratory simulation of forces similar to sewer
networks and observation of the relative disintegration of product within artificial and live sewer networks.
Variations to the disintegration test parameters have been developed based on laboratory testing within
different regions. A detailed description of the approach and considerations for differences in the test
parameters are provided below. These considerations should be taken into account when selecting a
methodology.
There are five tests currently referenced by national and international standards, guidelines and
specifications relating to the characterization of physical disintegration to determine if a product is suitable
for disposal via toilet flushing (Table B.5):
[19] [22] [13] [10]
a) Slosh box disintegration test variations – GD4, IWSFG, Spain, China, and Australia and New
[9] [12]
Zealand. This also includes the rapid mechanical disintegration test ‒ Belgium based on GD3.
[24]
b) Disintegration in the drainline test (UK WIS, Annex C ) and disintegration in the sewer test (UK WIS,
[24]
Annex E ). Both UK disintegration tests are to be performed to assess one product.
5.3.3 Disintegration testing method considerations
Considerations in applying these test methods are:
a) The versions of the slosh box disintegration test referenced in 5.3.2 a) contain multiple independent
variables, the setpoints of which significantly influence test outcomes (refer to Table B.5 for details):
1) test duration (measured in minutes or hours);
2) speed [the speed of the reciprocation of the slosh box or the speed of the rotation of the shake flask,
measured in revolutions per minute (r/min)];
3) volume of media [measured in litres (l)];
4) sieve opening size [the size of the sieve utilized for sample recovery after testing, measured in
millimetres (mm)];
5) pre-treatment duration [rinsing of samples, or static conditioning of a sample in open air prior to
testing, measured in minutes (min)];
6) temperature [measured in degrees Celsius (°C)].
b) The interaction of the independent variables (identified as “Parameter” in Table 1) directly impacts test
outcomes and variability.
Table 1 — General impact of individual test parameters on test outcomes
Parameter Impacts
Inclusion of a pre-conditioning step that introduces additional time for a product to
Preconditioning
lose strength prior to testing.
Speed Lower speed introduces less turbulence during testing.
Shorter test duration reduces the amount of force experienced by the sample, which is
Duration
directly related to time under testing.
Larger volume of water reduces the amount of turbulence generated during each artic-
Media Volume
ulation.
Temperature Lower temperature can reduce the amount of sample disintegration.
Small sieve opening size requires the sample to reach smaller dimensions in order to
Sieve opening size
pass through the sieve.
The transit time varies depending on the wastewater network design. Therefore, consider transit time and
other factors when applying the disintegration test.
c) When considering the slosh box disintegration tests for evaluating physical disintegration, a comparison
between versions indicates the IWSFG version will produce less disintegration than the AUS/NZ version
[18]
which in turn will produce less than the INDA/EDANA GD4 version, which in turn will produce less
[17]
than the INDA/EDANA GD3 version .
As noted in 5.3.2 b), the interaction of independent variables can be significant. The screening tests
developed to date are intended to evaluate the disintegration potential of products in a repeatable manner
under mechanical agitation in water that is intended to approximate conditions in a specific portion of sewer
networks.
[24]
d) The UK WIS disintegration in the sewer system shake flask tests differs from the slosh box-based
[24]
disintegration tests in terms of testing equipment, parameters and procedures (Table B.5). The WIS
shake flasks tests contain multiple independent variables, the setpoints of which significantly influence
test outcomes:
1) test duration (measured in minutes or hours);
2) speed (the speed of the reciprocation of the slosh box or the speed of the rotation of the shake flask,
measured in revolutions per minute [r/min]);
3) perforated plate sieve opening size (the size of the sieve utilized for sample recovery after testing,
measured in millimetres [mm]).
When considering the shake flask disintegration tests for evaluating physical disintegration, a comparison
[24]
between tests indicates the UK WIS Annex C test will produce less disintegration than the Annex E test.
Both the test duration and sieve endpoint are intended to reflect conditions within the wastewater transport
systems across the United Kingdom.
The interaction of independent variables within and among the disintegration tests can be significant.
As designed, the screening tests developed to date are intended to evaluate the disintegration potential
of products in a repeatable manner under mechanical agitation in water that is intended to approximate
conditions in a specific portion of sewer networks.
5.3.4 Municipal sewage pump test
A municipal sewage pump test is used to determine the compatibility of products with municipal sewage
pumping systems (Table B.9). The test employs a small municipal pump typically used in municipal
wastewater systems as a realistic worst-case scenario. The municipal sewage pump test measures pump
power increases and is not included within all methodologies.
5.4 Wastewater treatment systems
5.4.1 General
The intent of tests for evaluating compatibility of products with w
...

PR ISO TS/DTS 18671:2025
ISO/TC 224/WG 10
Secretariat: AFNOR
Date: 2026-03-16
Test methodologies for assessing the compatibility of wet wipes
and moist toilet tissue with the wastewater collection and
treatment systems, and appropriate labelling

DTS stage
Warning for WDs and CDs
This document is not an ISO International Standard. It is distributed for review and comment. It is subject to
change without notice and may not be referred to as an International Standard.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of
which they are aware and to provide supporting documentation.

A model document of an International Standard (the Model International Standard) is available at:

ISO #####-#:####(X)
2 © ISO #### – All rights reserved

Méthodologies d'essai pour évaluer la compatibilité des lingettes humides et du papier hygiénique humide avec
les systèmes de collecte et de traitement des eaux usées, et étiquetage approprié
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication
may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying,
or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO
at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
Email:
E-mail: [e-mail]
Website: www.iso.org
Published in Switzerland
iv
Contents
Foreword . vi
Introduction . vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Framework . 4
4.1 Context . 4
4.2 Domestic plumbing and drainline systems . 4
4.3 Wastewater transport systems . 5
4.4 Wastewater treatment systems . 6
4.5 Biodegradation and biodisintegration . 6
4.6 On-site domestic wastewater systems . 6
4.7 Environment . 6
5 Testing methodologies . 7
5.1 General . 7
5.2 Domestic plumbing and drainline systems . 8
5.3 Wastewater transport networks . 9
5.4 Wastewater treatment systems . 12
6 Labelling . 13
6.1 General . 13
6.2 When to apply labelling . 14
6.3 Packaging . 14
6.4 Location on the packaging . 14
6.5 Geometric shape and colour . 14
6.6 Size . 14
6.7 Advisory text . 14
Annex A (informative) Examples of labelling . 15
Annex B (informative) Summary of current test methods . 16
Bibliography . 32

v
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'sISO’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 WG 10, Drinking water, wastewater and
stormwater systems and services.
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
Introduction
Flushing of productproducts that isare incompatible with sewerage networks can contribute to:
— blockages in home plumbing and smaller sewer pipes, and blockages in pumps, ;
— increased screening of solids for solid waste disposal;
— increased burden for treatment processes both onsiteon-site and at the municipal level, with non-
degradable materials which can lead to further downstream environmental impacts.;
— increased risk of sewer blockages at reduced sewer flows.
Consistent labelling and education to inform consumers of proper disposal of products is important to help
reduce adverse effects on wastewater collection and treatment systems. Application of this document
presupposes that not only the producers but also all the concerned parties about export, retail or consumption
are aware of the legislation and regulations pertaining to wet wipes and moist toilet tissues.
This document provides recommendations regarding:
— labelling and the use of a symbol to be used with non-flushable product packages indicating
incompatibility with the wastewater system. ;
— If a product is compatible with a wastewater collection and treatment system the producer may use a
suitable symbol in compliance conforming with the relevant local or national standard, standards, or in
compliance with legal requirements of the targeted country or region.
— the use of any of five different available methodologies worldwide for assessing product compatibility with
the wastewater collection and treatment system and subsequent labelling.
TheThis document describes currently published test methodologies for assessing compatibility of products
with wastewater networks. Each methodology comprises of different methods that must be used to determine
wastewater network compatibility. It is important to note that each of the methodologies are stand alone, and
the individual methods are not designed to be interchanged. They are outlined in Annex Bthe appendices,,
detailing where they are being used and differences in testing approach, enabling the reader to select whether
a particular methodology is more relevant to their geographical region.
vii
1 Test methodologiesScope
The products that this document is applicable for areassessing the
compatibility of wet wipes and moist toilet tissue with the wastewater
collection and treatment systems, and appropriate labelling
21 Scope
. This document identifiesprovides test methodologies for assessing the compatibility of wet wipes and moist
toilet tissue with the wastewater systemcollection and treatment systems, and it specifies appropriate
labelling for products deemed incompatible. The products that this document is applicable for are wet wipes
and moist toilet tissue.
This document does not cover:
— • dry toilet paper as defined and covered by other ISO documents.;
— • chemical toilets or compost toilets that are not connected to sewer systems.;
— • macerator and vacuum sewer systems;
— • water soluble polymers.
32 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, Service activities relating to drinking water supply, wastewater and stormwater systems —
Vocabulary
43 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 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/
4.13.1 3.1
biodegradation
degradation due to the biological environment
[SOURCE: ISO/TR 13329:2024 (en),19057:2017, 3.42, modified — Note 1 to entry was removed.]
4.23.2 3.2
disintegration
breaking of material into small pieces in water under specified conditions
ISO #####-#:####(X/DTS 18671:(en)
[SOURCE: ISO 12625-17:2021(en),, 3.1, modified from — “process that is characterized by a material
breaking, in order” was changed to be applicable to the wet wipes and moist toilet tissue]“breaking of
material”.]
4.33.3 3.3
methodology
collection of standards, procedures and supporting methods that define the complete approach to the
development of a product or system
[SOURCE: ISO/IEC 21827:2008(en),, 3.22]
4.43.4 3.4
mineralization
decomposition of organic matter or organic substances into carbon dioxide, water and the hydrides, oxides or
other mineral salts
[SOURCE: ISO 11074:20152025, 3.3.19], modified — “final stage of the biodegradation” was changed to
“decomposition”.]
4.53.5 3.5
moist toilet tissue
moist toilet paper
prewetted nonwoven material intended for sanitary use after using the toilet
Note 1 to entry: products Products labelled as “moist toilet scope for this document and associated labelling. scope for
this document and associated labelling.”paper” are made from nonwoven material and are not considered as “toilet
paper” for the purpose of this document.
[Source: Based on ISO 12625-1:2019 (en), 3.60]

3.6
[SOURCE: ISO 12625-1:2019, 3.60, modified — The term was changed from “toilet paper” to “moist toilet
tissue”; in the definition, “tissue paper” was changed to “prewetted nonwoven material”.]
3.6
persistent
existing or remaining in the same state for an indefinitely long time
[SOURCE: ISO/TR 18307:2001]
, 3.7111, modified — The admitted terms “persistence” and “enduring” were removed.]
4.63.7
plastic, noun
solid material which contains, as an essential ingredient, one or more high molecular mass polymers and
which is formed (shapeshaped) during either manufacture of the polymer or the fabrication into a finished
product by either heat and/or pressure, or both
Note: 1 to entry: In different regions there are legal definitions of plastic(s). Users of this specificationdocument are
advised to check the definition of plastic in the geographical or jurisdictional region where products are marketed.
[SOURCE: ISO 21070:2017, 3.2.11 modified – Note — The original Notes to entry were removed, and a new
note was added.]
© ISO #### 2026 – All rights reserved
4.73.8
3.8
toilet paper
bathroom tissue
bath tissue
dry toilet paper
tissue paper intended for sanitary use after using the toilet
Note 1 to entry: products Products labelled as “moist toilet paper” are often made from nonwoven material and are not
considered as “toilet paper” for the purpose of this document.
[ISO 12625-1:2019(en), 3.60,]
3.9
[SOURCE: ISO 12625-1:2019, 3.60, modified — In the note to entry, “are not in the scope of this document”
was changed to “ are not considered ‘toilet paper’ for the purpose of this document”.]
3.9
transit time
sewer residence time
in-sewer travel time
wastewater residence time
amount of time a given volume of wastewater resides in a sewer system between a designated beginning and
end point
Note 1: to entry: Sewer systems include pumping stations and treatment plants.
4.83.10 3.10
toilet
water closet
WC
fixed receptacle into which a person may urinate or defecate, typically consisting of a large bowl connected to
a cistern for flushing
[SOURCE: ISO/TR 24524:2019, 3.7], modified — “water closet” and “WC” were added as admitted terms.]
4.93.11 3.11
wet wipe
small piece of pre-moistenedpremoistened or pre-wettedprewetted material which is conceived, designed
and placed on the market for single-use (disposable) and intended for personal care or domestic use
Note 1: to entry: Personal care is intendintended to be used for hygiene purposes, these include cleansing and caring of
skin of both human adults and babies e.g. cosmetics, baby wipes, intimate care wipes.
Note 2: to entry: A domestic use wet wipe is intended to be used in domestic premises. These include wet wipes used for
household cleaning purposes, e.g. wipes used to clean.
Note 3: Pre-wetted to entry: Prewetted wipes typically contain an impregnation liquid which has been added to the wipe
before it is placed on the market.
Note 4 to entry: Adapted from Reference [11][Source: EU Official Journal C216 [11], p.38, modified]

ISO #####-#:####(X/DTS 18671:(en)
.
54 Framework
5.14.1 Context
5.1.1 General
References [9] [9] to[20] [20] arewere the basis for drafting this document. These documents are current
national standards, international guidelines and specifications which have been adopted in some regions.
Table B.1Table B.1 provides an overview of the various test methodologies in use, when they were published,
their relevance and the regions or countries where they are being applied. When selecting a particular
methodology described in Annex BAnnex B,, based on the aspects outlined in this document, users should
follow the methodology as prescribed. Test methods from different methodologies should not be
interchanged. The key elements of a wastewater system to be considered in test methods for evaluating
products suitable for toilet disposal are described in ISO/TR 24524. The design, operation and serviceability
of sewerage facilities can vary widely from country to country.
The key elements are:
a) a) toilets;
b) b) drainlines (including domestic pumps);
c) c) wastewater transport systems (including municipal pumps) and screening systems;
d) d) treatment processes;
e) e) environment.
The wastewater system comprises elements (a) to (d). Material that enters wastewater treatment plants can
either be removed via degradation, integration into the semi-solid phase, volatilized into gaseous form or
released in the treated effluent discharged from the wastewater treatment plant to receiving environments.
Products disposed into wastewater systems can also reach receiving environments without treatment. From
time to time, sewers overflow to the environment for a multitude of reasons. Given that products disposed
into wastewater systems have the potential to cause environmental harm if untreated, products should be
[7]
evaluated for environmental and treatment plant compatibility [7].
5.24.2 Domestic plumbing and drainline systems
5.2.14.2.1 Toilets
The purpose of a toilet is to dispose of human excreta (i.e. urine, menses, vomit and faeces) by using water to
flush it through a drainline to another location for disposal, thus maintaining a separation between humans
and their waste. Any product discharged via a toilet should not adversely affect the intended operation of the
[7]
toilet. The typical flush volume for new toilets varies from 2 l to 6 l [7].
5.2.24.2.2 Drainlines
Drainline design, configuration, construction and maintenance can impact the ability of waste to pass through
a drainline. Typically, material flushed from a toilet into a drainline moves along the drainline with water from
toilet flushing. Failure of flushed product to exit the drainline can result in blocked plumbing within the
property, blocked external drainage pipelines, the generation of foul odours or allowthe product to drydrying
© ISO #### 2026 – All rights reserved
out and adhereadhering to the pipe surface. Product intended to be discharged via a toilet should clear the
drainline and reach the sewer without adversely affecting the operation of the drainline.
5.34.3 Wastewater transport systems
5.3.14.3.1 General
The design, layout and configuration of wastewater transport systems vary among and within countries due
to various factors including regulation, population density, system age, geographic and topographic features,
and climatic conditions.
5.3.24.3.2 Sewers
5.3.2.14.3.2.1 Wastewater network hydraulics and solids transport
The purpose of the sewer is to receive discharges from drainlines and convey to wastewater treatment
systems. Flow in wastewater conveyance systems typically occurs via gravity flow, pumped flow, vacuum
pressure or a combination of these. Flow can be intermittent or continuous and is dependent on the sewer
design, wastewater flow conditions influenced by either rainfall and/or peak discharge usage, or both. In small
diameter pipes (less than 225 mm), there is an elevated risk that products introduced into the sewer system
can become snagged on pipe imperfections or tree roots, and resultthus resulting in pipe blockages.
5.3.2.24.3.2.2 Wastewater transport network velocity
Wastewater velocities vary significantly as a result of a range of factors including sewer design, climatic
conditions, topography and volume. In general, sewers are designed to achieve a velocity sufficient to
[14]
transport solids to prevent deposition and decomposition in the sewer. [14].
5.3.2.34.3.2.3 Transit time
Surveys of sewer transit times indicate the typical duration to the first screen or pump is between 30 minutes
and 6 hours, although it can be less than 10 minutes for densified residential areas and it can reach several
[15]][[23]][[24] ][[25]
days. [15],[23],[24],[25]. Transit time should be considered when selecting tests methodologies.
Local conditions can require a higher minimum cross-sectional velocity value or a minimum sewer slope value.
5.3.2.44.3.2.4 Temperature
The temperature of the wastewater can vary depending on geographic location and season. It can typically
[7]
range from 5 °C to 30 °C [7].
5.3.34.3.3 Pumping stations
Pumps are commonly used to facilitate wastewater transport where this cannot be achieved by gravity alone.
They are typically utilized within the transport system from the point of discharge from the customer property
to the nearest point where gravity flow is possible or to the treatment plant. Screens or grinders can be
installed ahead of the pumps or other downstream infrastructure, including overflow outlets, and immediately
before the influent point of the treatment system to protect equipment from becoming blocked. Products
greater than a certain size can foul screens, resulting in an elevated load of solid waste to landfill, increased
[7]
maintenance or potential blockages leading to sewer overflows and flooding [7].
Solids transported in sewers can accumulate and cause pump malfunction in pumping stations before
reaching wastewater treatment plants. Such events are observed worldwide.
ISO #####-#:####(X/DTS 18671:(en)
5.44.4 Wastewater Treatmenttreatment systems
5.4.14.4.1 General
A product that enters a wastewater treatment plant should not unduly affect the ability of that plant to meet
legislated or licence conditions, and should not result in additional operational costs, nor adversely impact the
environment. The effluent discharged from wastewater treatment plants should not pose an increased
[7]
environmental risk [7]. .
5.4.24.4.2 Settling
The majority of solids that enter a wastewater treatment plant are removed through initial screening and
subsequent settling throughout the treatment process. The rate of settling within a wastewater treatment
plant is measured by the settling velocity. The settling rate of a product is affected by particle size and density,
along with system design, operation and capacity. A settling test should be used to evaluate the settling rate
[7]
for products [7].
5.54.5 Biodegradation and biodisintegration
The purpose of wastewater treatment is to separate and treat the solids and clean the incoming wastewater
to a level suitable for discharge or reuse. Organic wastewater solids are typically broken down biologically
using aerobic or anaerobic digestion processes. The dewatered digested sludge solids (also called biosolids)
can then be incinerated, landfilled, or land applied to the land.
To evaluate if a product is compatible with biological wastewater treatment process and can be fully treated
such that no product beis recognizable in the effluent leaving municipal wastewater treatment systems or in
[23]
the post-treatment products of treatment sludges [23],, laboratory tests should be utilized to evaluate the
potential of products to break down biologically under aerobic and anaerobic conditions.
These tests can also be utilized to determine if a product contains materials that do not degrade biologically
in aerobic or anaerobic conditions and are therefore likely to be discharged in the wastewater effluent or
persist in biosolids which could be subsequently land applied to the land, or if discharged directly to a receiving
environment.
5.64.6 OnsiteOn-site domestic wastewater systems
On-site domestic wastewater systems (ODWS) are widely used throughout the world to collect, treat,
discharge, disperse or reuse domestic wastewater in areas where centralized sewerage systems are not viable
or not currently available. An ODWS is often a self-contained unit designed to collect, treat and discharge,
disperse or reuse wastewater. The testing protocols proposed in this document do not distinguish between
ODWS and centralized treatment systems. However, methodologies take into account aspects of different
types of ODWS, including more basic systems.
For ODWS, a methodology that includes a toilet and drainline test, a domestic pump test, a settling test and
anaerobic and aerobic biodisintegration tests should be utilized to evaluate if the product can be transported
with wastewater solids through the toilet and downstream pipework and domestic pumps, if the product will
settle inside the tank, and if it will be mineralized.
5.74.7 Environment
For products covered by the scope of this document, consideration should be given to environmental safety,
including assessment of toxicity, bioaccumulation and persistence of their components.
© ISO #### 2026 – All rights reserved
65 Testing methodologies
6.15.1 General
Evaluation of products for compatibility with wastewater systems follow two predominant testing
[18] [24] [18]
methodologies. The two primary models are GD4 [18] and the UK WIS [24]. The GD4 [18] model has
been utilized with several variations including the removal and modification of test parameters and pass or
fail criteria. The details of these modifications are outlined in this document. The pass-fail criteria for each of
those referenced testing regimes can be found in the documents listed in the bibliography and are summarized
in Annex BAnnex B. When selecting a methodology to use, it should be adopted in full. The methodologies
were designed to be stand alone. The tests are not designed to be interchanged.
When adopting a methodology for a country or region it is important to understand the sewage facilities of
the country in question and select a methodology that is compatible with those assets.
Figure 1Figure 1 outlines the approach for determining whether wet wipes and moist toilet tissue are in scope
for this document and the associated labelling.
Yes
Does the product contain plastics as per
Assessment based on this TS should
relevant regulations
not apply but it is recommended
that the product is marked with a
‘do not flush’ or ‘tidy man’ Symbol.
No
Users should be aware of applicable
No
regulations.
Is the product designed for, marketed for,
or commonly used in a bathroom setting
or for toileting purposes?
Assessment against the relevant
methodology should not apply but
Yes recommend that the product is
marked with a ‘do not flush’ or ‘tidy
Is the product designed to come in direct
man’ Symbol
No
contact with human fluids e.g. faeces,
menses, urine or germs?
Yes
No
Product is not compatible with
Does the product pass each of the tests set
wastewater systems and should be
out in the relevant test methodology?
marked with a ‘do not flush’ or ‘tidy
man’ symbol
Yes
The product is compatible with a
wastewater collection and treatment
system and the producer may use a
suitable symbol in compliance with the
relevant local or national standard, or
legal requirements of the targeted country
or region.
ISO #####-#:####(X/DTS 18671:(en)

Figure 1:— Flowchart with steps for assessing the compatibility of wet wipes and moist toilet tissue
with the wastewater collection and treatment systems, and to determine appropriate labelling
NOTE : The relevant test methodologies are outlined in Table B.1Table B.1.
Current available testing methodologies have key similarities. This document identifies their differences and
options for applying them.
[18] [24]
Both GD4 [18] and the UK WIS [24] evaluate performance of products in infrastructure from the toilet
through residential plumbing, wastewater transport infrastructure and wastewater treatment. The local
standards developed for countries including Belgium, Spain, China, Australia, and New Zealand are all based
[18] [18]
on GD4 [18]. The IWSFG is also based on GD4. [18]. Note that several Several of these have modifications
for operating conditions and pass or fail criteria. The reason for these modifications is to address different
perspectives regarding protection of, and product compatibility with, wastewater systems.
6.25.2 Domestic plumbing and drainline systems
6.2.15.2.1 General
A product discharged via a toilet should not adversely affect the intended operation of the drainline or
sewerage system. Details of the test methods currently in use for domestic plumbing and drainline systems
are provided in Tables B.2Tables B.2 and B.3B.3.
© ISO #### 2026 – All rights reserved
6.2.25.2.2 Toilet clearance test
The product should not block or allow the toilet to surcharge (overload) or overflow. The purpose of toilet
[18]
clearance testing is to assess that products do not adversely affect toilet operation. GD4 [18] and its variants
[24]
integrate the drainline clearance test with the toilet bowl clearance test whereas the UK WIS [24] separates
[18]
toilet testing from the drainline clearance test. For GD4 [18] the material flushed down the toilet includes
simulated faecal material, dry toilet paper and the tested product to simulate user behaviour (4 people),
[24]
whereas the UK WIS [24] uses only the tested product alone.
[18]
The GD4 [18] method allows the single use of a plunger, wherein one replicate is allowed to be plunged,
[18]
while modifications to this have been made in methodologies that incorporate the GD4 [18] Toilet toilet
and Drainlinedrainline test.
6.2.35.2.3 Drainlines
6.2.3.15.2.3.1 Drainline clearance test
A drainline clearance test should be used to confirm that a product exits the drainline without causing backup
[18] [24]
of water and materials. The intent of the drainline clearance tests of GD4 [18] and the UK WIS [24] are
[18]
similar, i.e. that product moves along the drainline and exits within a certain number of flushes. The GD4
[18] test methodology is adjustable for different toilet flush volumes and to account for the slope of the
drainline. The details of typical international variations for these parameters are outlined in ISO/TR 24524
[7].
[18]
GD4 [18] assesses the movement of material down the drainline using a calculation called the centre of
mass. This establishes that the material is moving down the drainline, accounting for pieces if the material
starts to separate as it moves. The centre of mass is the weighted average position of the material (mass
[9]
weighted centre). It has been replaced by centre of movement in AS/NZS 5298 [9],5328, which is the average
position of the material. The material flushed down the drainline includes simulated faecal material, dry toilet
paper and the tested product in a given sequence to simulate userthe behaviour of users (4 people) using the
toilet.
6.2.3.25.2.3.2 Drainline disintegration test
In order to assess if a product is capable of disintegrating sufficiently, to an extent that minimises risk of
blockage to a pipe or pumps, as it passes through the drainline, the UK has developed a drainline disintegration
test. This test has not been adopted elsewhere as the tests associated with the disintegration in alternative
test methods address this concern.
6.2.45.2.4 Household pump test
[18]
GD4 [18] includes a household pump test in addition to the toilet and drainline clearance test. The
[18]
household pump test is not necessarily part of local requirements based on GD4 [18]. A household pump
test (see Clause B.2Annex B.4)) should be used to assess the compatibility of a product with household sewage
pump systems to assess that the product does not clog, accumulate within or otherwise interfere with normal
system operation. The test seeks to simulate the conditions of operation for a household pump by using a
typical household wastewater pump (Table B.2(Table B.2)) in a container connected to a discharge pipe under
laboratory conditions.
6.35.3 Wastewater transport networks
6.3.15.3.1 General
Disintegration is a primary test used to assess the compatibility of a product with wastewater transport
systems including pumping systems and downstream pipework. For this purpose, a disintegration test is
ISO #####-#:####(X/DTS 18671:(en)
[18]
included in all test methodologies and supplemented by a municipal pump test in GD4 [18] and some of its
variants. Details of the test methods currently in use are provided in Table B.5Table B.5.
6.3.25.3.2 Disintegration testing methods
[24]
There are two tests available, the slosh box disintegration test and the UK WIS [24] sewer system shake
flask test. Both test methodologies have been developed through laboratory simulation of forces similar to
sewer networks and observation of the relative disintegration of product within artificial and live sewer
networks.
Variations to the disintegration test parameters have been developed based on laboratory testing within
different regions. A detailed description of the approach and considerations for differences in the test
parameters are provided below. These considerations should be taken into account when selecting a
methodology.
There are five tests currently referenced by national and international standards, guidelines and specifications
relating to the characterization of physical disintegration to determine if a product is suitable for disposal via
toilet flushing (Table B.5(Table B.5):):
[19] [22]
a) Slosh Box Disintegration Test box disintegration test variations – GD4 [19],, IWSFG [22],, Spain
[13] [10] [9]
[13],, China, [10], and Australia and New Zealand. [9]. Also including This also includes the rapid
[12]
mechanical disintegration test -‒ Belgium [12] based on GD3.
[24]
b) Disintegration in the drainline test (UK WIS Appendix , Annex C [24])) and disintegration in the sewer
[24]
test (UK WIS, Annex E Appendix C [24]).). Both UK disintegration tests are to be performed to assess
one product.
6.3.35.3.3 Disintegration testing method considerations
Considerations in applying these test methods are:
a) a) The above-referenced versions of the slosh box disintegration test referenced in 5.3.2 a) contain
multiple independent variables, the setpoints of which significantly influence test outcomes (refer to
Table B.5Table B.5 for details):
1) 1) test duration (measured in minutes or hours));
2) 2) speed [the speed of the reciprocation of the slosh box or the speed of the rotation of the shake flask,
measured in revolutions per minute (r/min)])];
3) 3) volume of media [measured in litres (l)])];
4) 4) sieve opening size [the size of the sieve utilized for sample recovery after testing, measured in
millimetersmillimetres (mm)],)];
5) 5) pre-treatment duration [rinsing of samples, or static conditioning of a sample in open air prior to
testing, measured in minutes (min)])];
6) 6) temperature [measured in degrees Celsius ((°C)].
b) b) The interaction of the independent variables (identified as “Parameter” in Table 1Table 1)) directly
impacts test outcomes and variability.
© ISO #### 2026 – All rights reserved
Table 1— General impact of individual test parameters on test outcomes
Parameter Impacts
Inclusion of a pre-conditioning step that introduces additional time for a product to
Preconditioning
lose strength prior to testing.
Speed Lower speed introduces less turbulence during testing.
A shorterShorter test duration reduces the amount of force experienced by the sample,
Duration
which is directly related to time under testing.
A largerLarger volume of water reduces the amount of turbulence generated during
Media Volume
each articulation.
Temperature A lowerLower temperature can reduce the amount of sample disintegration.
A smallSmall sieve opening size requires the sample to reach smaller dimensions in
Sieve opening size
order to pass through the sieve.
The transit time varies depending on the wastewater network design. Therefore, consider transit time and
other factors when applying the disintegration test.
c) c) When considering the slosh box disintegration tests for evaluating physical disintegration, a
comparison between versions indicates the IWSFG version will produce less disintegration than the
[18]
AUS/NZ version which in turn will produce less than the INDA/EDANA GD4 [18] version, which in turn
[17]
will produce less than the INDA/EDANA GD3 version [17].
As noted in 5.3.25.3.2 item b)), the interaction of independent variables can be significant. The screening tests
developed to date are intended to evaluate the disintegration potential of products in a repeatable manner
under mechanical agitation in water that is intended to approximate conditions in a specific portion of sewer
networks.
[24]
d) d) The UK WIS [24] disintegration in the sewer system shake flask tests differs from the slosh box-
based disintegration tests in terms of testing equipment, parameters and procedures (Table B.5(Table
[24]
B.5).). The WIS [24] shake flasks tests contain multiple independent variables, the setpoints of which
significantly influence test outcomes:
1) 1) test duration (measured in minutes or hours));
2) 2) speed (the speed of the reciprocation of the slosh box or the speed of the rotation of the shake flask,
measured in revolutions per minute [r/min]) ]);
3) 3) perforated plate sieve opening size (the size of the sieve utilized for sample recovery after testing,
measured in millimetersmillimetres [mm])]).
When considering the shake flask disintegration tests for evaluating physical disintegration, a comparison
[24]
between tests indicates the UK WIS [24] Annex C test will produce less disintegration than the Annex E test.
Both the test duration and sieve endpoint are intended to reflect conditions within the wastewater transport
systems across the United Kingdom.
The interaction of independent variables within and among the disintegration tests can be significant. As
designed, the screening tests developed to date are intended to evaluate the disintegration potential of
products in a repeatable manner under mechanical agitation in water that is intended to approximate
conditions in a specific portion of sewer networks.
ISO #####-#:####(X/DTS 18671:(en)
6.3.45.3.4 Municipal Sewage Pumpsewage pump test
A municipal sewage pump test is used to determine the compatibility of products with municipal sewage
pumping systems (Table B.9(Table B.9).). The test employs a small municipal pump typically used in
municipal wastewater systems as a realistic worst-case scenario. The municipal sewage pump test measures
pump power increases and is not included within all methodologies.
6.45.4 Wastewater Treatmenttreatment systems
6.4.15.4.1 General
The intent of tests for evaluating compatibility of products with wastewater treatment systems areis to assess
that the product is not buoyant and can settle within a short period of time and not resuspend into the water
column. In this case, the settling test should be used. The second suite of tests are screening tests to assess the
ability of the product to biologically degrade under aerobic or anaerobic conditions found in onsiteon-site and
municipal wastewater treatment systems. In this case, a biodegradation or biodisintegration test should be
used.
6.4.25.4.2 Settling
[18] [24]
This test is relatively consistent between the GD4 [18] (including all variations) and the UK WIS [24] test
[24]
methodologies (Table B.6(Table B.6).). The UK WIS [24] evaluates if product components following
[18]
preconditioning will settle, whereas GD4 [18] evaluates the rate of settling for the product.
6.4.35.4.3 Biodegradation and biodisintegration tests
6.4.3.15.4.3.1 General
Testing assesses the biodegradation or persistence of products in receiving environments.
Biodegradation or biodisintegration tests can be used to evaluate compatibility with wastewater treatment
and environmental persistence. The use of the product fibre compositional analysis can be considered to avoid
plastic fibres in the product. A manufacturer attestation can be considered to avoid plastic content in the
product.
There are currently several laboratory test approaches to determine the potential for a product to biodegrade
in wastewater treatment, including:
— • Biodisintegrationbiodisintegration laboratory test methods;
— • Biodegradationbiodegradation (respirometric) laboratory test methods.
There are also two additional approaches to determining the fibre composition of a product:
— • Productproduct fibre compositional analysis;
— • Requestingrequesting an attestation from the manufacturer.
6.4.3.25.4.3.2 Current approaches
There are fourFour test methods are currently used to assess biodegradation (Table B.7(Table B.7 and
B.8B.8).). Biodisintegration tests are a surrogate for biodegradation. Test method resolution to allow
identification of biodegradable and non-biodegradable materials is roughly equivalent but varies based on the
current pass or fail criteria.
The four tests are:
© ISO #### 2026 – All rights reserved
[18]
— • GD4 [18] FG505.R1(18) (2018) Aerobic (A)aerobic biodisintegration (A);
[18]
— • GD4 [18] FG506.R1(18) (2018) Anaerobic (A)anaerobic biodisintegration (A);
— • OECD 3
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