ISO 5667-27:2025
(Main)Water quality — Sampling — Part 27: Guidance on sampling for microplastics in water
Water quality — Sampling — Part 27: Guidance on sampling for microplastics in water
This document specifies the basic methods for sampling suspended microplastics in water (domestic water, freshwater, seawater, treated wastewater and untreated wastewater), for their subsequent characterization. Suspended particles can also include synthetic or semi-synthetic polymeric materials (such as rubber). This document does not cover chemical analysis, biological (ecotoxicological) methods or physical methods, nor the pre-treatment or digestion methods intrinsic to such analyses. This document covers general methodologies: — for grab sampling, sampling using a set of successive filters of different pore sizes (cascade filtration), for water samples with low, medium and high content of suspended solids, and — for net sampling using, for example, manta, plankton or neuston nets.
Qualité de l'eau — Échantillonnage — Partie 27: Recommandations pour l'échantillonnage des microplastiques dans l'eau
General Information
Standards Content (Sample)
International
Standard
ISO 5667-27
First edition
Water quality — Sampling —
2025-03
Part 27:
Guidance on sampling for
microplastics in water
Qualité de l'eau — Échantillonnage —
Partie 27: Recommandations pour l'échantillonnage des
microplastiques dans l'eau
Reference number
© ISO 2025
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: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principles and general considerations . . 3
4.1 Methodologies .3
4.1.1 General .3
4.1.2 Grab sampling .3
4.1.3 Volume-reduced sampling .3
4.2 Selecting the most appropriate sampling method .4
4.3 Sampling volume .6
4.4 Quality control .6
4.4.1 General .6
4.4.2 Sources of sampling errors .7
4.4.3 Blanks .7
4.5 Sampling plan .9
4.5.1 General .9
4.5.2 Sampling points .9
4.5.3 Sampling frequency, duration and timing .9
5 Reagents . 9
6 Apparatus . 10
6.1 Grab sampling method .10
6.2 Cascade filtration methods .11
6.3 Net sampling . 12
7 Sample handling .16
7.1 General .16
7.2 Grab sampling method .16
7.3 Cascade filtration methods .16
7.4 Net sampling .17
8 Procedures . 17
8.1 Grab sampling method .17
8.2 Cascade filtration method 1: Sampling of domestic water, treated wastewater and
water samples with low suspended solid content .18
8.3 Cascade filtration method 2: Sampling of untreated wastewater or water samples with
medium or high suspended solid content .19
8.4 Net sampling . 20
9 Sampling report .21
Bibliography .26
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 document 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 147 Water quality, Subcommittee SC 6,
Sampling (general methods).
A list of all parts in the ISO 5667 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
iv
Introduction
Microplastic occurrence in the environment is a prominent concern both to the public and to the scientific
community. Determining the amount and distribution of microplastics in water bodies and domestic water
[1]-[6]
is therefore a critical task. However, the methodology for sampling microplastics in water samples is
still lacking in precision. Consistent methodology is only starting to emerge, but still no universal protocol
exists for the sampling of these contaminants in water.
[7]
The presence of small plastic fragments in the ocean was first reported in 1972, but it was in 2004 that
the term “microplastics” was proposed for the first time to describe plastic particles of a few micrometres in
[8]
diameter. Since then, a wealth of information became available on the abundance and type of microplastics
in the marine environment, freshwater and estuarine systems. However, the different studies have used
diverse techniques to sample, extract, treat and detect microplastic present in water.
There are many reasons why different studies investigating microplastic occurrence in water and
wastewater show different results. The disparity between some of the findings (for microplastic type
and abundance) can be partially explained by the fact that differing sampling techniques have been used.
Variables pertaining to both time of year and time of day, flow rate and volume of water sampled, grab
sampling or sieving the water over an extended period, the use of plastic containers or tubing, selection of a
few parts of the sample for analysis, or dissimilar devices to capture the microplastic fragments, can be the
causes of variation in study results.
While several standards for water sampling and water quality already exist (e.g. ISO 5667 series and, in
particular, ISO 5667-17), microplastics as particular determinands pose a specific challenge which requires
a more specific approach. For example, microplastics sampling requires the use of very specific materials
for collecting, handling and storing to avoid cross-contamination. Also, microplastic buoyancy can vary
depending on their composition, size, shape or colonization by microorganisms, and microplastics are not
homogeneously distributed in the water column. Therefore, a more targeted and detailed set of sampling
protocols is required to account for these differences. To better understand the fate and impact of
microplastics in the environment, a more specific standardized sampling approach should be adopted and
applied.
v
International Standard ISO 5667-27:2025(en)
Water quality — Sampling —
Part 27:
Guidance on sampling for microplastics in water
WARNING — Persons using this document should be familiar with normal laboratory practice. This
document does not purport to address all of the safety problems, if any, associated with its use. It
is the responsibility of the user to establish appropriate safety and health practices and to ensure
compliance with any na
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.