EN ISO 7027-2:2019

Water quality - Determination of turbidity - Part 2: Semi-quantitative methods for the assessment of transparency of waters (ISO 7027-2:2019)

This document specifies the following semi-quantitative methods for the assessment of transparency of waters:
a)    measurement of visual range using the transparency testing tube (applicable to transparent and slightly cloudy water),  see Clause 4;
b)    measurement of visual range in the upper water layers using the transparency testing disc (especially applicable to surface, bathing water, waste water and often used in marine monitoring), see 5.1;
c)    measurement of visibility by divers in a destined depth, see 5.2.
NOTE       The quantitative methods using optical turbidimeters or nephelometers are described in ISO 7027-1.

Wasserbeschaffenheit - Bestimmung der Trübung - Teil 2: Semi-quantitative Verfahren zur Beurteilung der Lichtdurchlässigkeit (ISO 7027-2:2019)

Dieses Dokument legt die folgenden semi quantitativen Verfahren für die Beurteilung der Transparenz von Gewässern fest:
a)   Messung der Sichtweite mithilfe des Transparenzprüfröhrchens (anwendbar für klares und leicht getrübtes Wasser), siehe Abschnitt 4;
b)   Messung der Sichtweite der oberen Wasserschichten mithilfe der Sichtscheibe (speziell anwendbar für Oberflächengewässer, Badegewässer, Abwässer und oftmals in der Überwachung im maritimen Bereich), siehe 5.1;
c)   Messung der Sichtweite mittels Sichtscheibe durch Taucher in einer vorgesehenen Tiefe, siehe 5.2.
ANMERKUNG   Die quantitativen Verfahren unter Verwendung optischer Trübungsmessgeräte oder Nephelometer sind in ISO 7027 1 beschrieben.

Qualité de l'eau - Détermination de la turbidité - Partie 2: Méthodes semi-quantitatives pour l'évaluation de la transparence des eaux (ISO 7027-2:2019)

This document specifies the following semi-quantitative methods for the assessment of transparency of waters:
a)    measurement of visual range using the transparency testing tube (applicable to transparent and slightly cloudy water),  see Clause 4;
b)    measurement of visual range in the upper water layers using the transparency testing disc (especially applicable to surface, bathing water, waste water and often used in marine monitoring), see 5.1;
c)    measurement of visibility by divers in a destined depth, see 5.2.
NOTE       The quantitative methods using optical turbidimeters or nephelometers are described in ISO 7027-1.

Kakovost vode - Ugotavljanje motnosti - 2. del: Semikvantitativne metode za ocenjevanje prosojnosti vode (ISO 7027-2:2019)

Ta dokument določa naslednje semikvantitativne metode za ocenjevanje prosojnosti
vode:
a) merjenje vidnega območja z uporabo epruvete za preskušanje prosojnosti (uporablja se za prosojno in
rahlo motno vodo), glej točko 4;
b) merjenje vidnega območja v zgornjih slojih vode z uporabo diska za preskušanje prosojnosti
(uporablja se zlasti za površinsko, kopalno in odpadno vodo ter pogosto pri monitoringu morja),
glej točko 5.1;
c) merjenje vidljivosti, ki ga izvedejo potapljači na predvideni globini, glej točko 5.2.
OPOMBA: Kvantitativne metode z uporabo optičnih turbidimetrov ali nefelometrov so opisane v standardu ISO 7027-1.

General Information

• Status: Published
• Publication Date: 19-Feb-2019
• Withdrawal Date: 30-Aug-2019
• ICS: 13.060.01 - Water quality in general
• ICS: 13.060.60 - Examination of physical properties of water
• Technical Committee: CEN/TC 230 - Water analysis
• Drafting Committee: CEN/TC 230/WG 1 - Physical and biochemical methods
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 20-Feb-2019
• Completion Date: 20-Feb-2019
• Ref Project: SIST EN ISO 7027-2:2019 - Water quality - Determination of turbidity - Part 2: Semi-quantitative methods for the assessment of transparency of waters (ISO 7027-2:2019)

Relations

• Replaces: EN ISO 7027:1999 - Water quality - Determination of turbidity (ISO 7027:1999)
• Effective Date: 08-Jun-2022

Overview

EN ISO 7027-2:2019 - Water quality - Determination of turbidity - Part 2 - specifies semi-quantitative methods to assess water transparency. Published by CEN/ISO, it complements ISO 7027-1 (quantitative turbidity measurement) and is intended for laboratory and in‑situ (field) use. The standard covers three main approaches: the transparency testing tube, the transparency (Secchi‑type) testing disc, and diver visibility assessments, and provides guidance on sampling, apparatus and expression of results.

Key topics and technical requirements

• Scope and purpose: Procedures for semi‑quantitative assessment of transparency of surface waters, bathing waters, wastewater and marine environments.
• Methods covered:
  • Transparency testing tube (laboratory or close‑to‑site): specifies apparatus dimensions (glass tube ~600 mm ±10 mm length, internal diameter ~25 mm ±1 mm, graduations 10 mm), shielding, test print or mark and constant light source requirements for visual range measurement.
  • Transparency testing disc (field/Secchi‑type): measurement of visual range in upper water layers; widely used in surface, bathing and marine monitoring.
  • Diver visibility: standardised approach for estimating visibility at designated depths by trained divers.
• Sampling and sample handling: Clean sample bottles, bubble‑free filling and prompt measurement; cleaning recommendations (e.g., acid or surfactant) are referenced.
• Data expression and reporting: Procedures for expressing visual range and transparency results, including notes on estimating the attenuation coefficient (useful in marine monitoring).
• Quality and validation: References to interlaboratory field study results (Annex B) and normative references such as CIE S 017 for lighting vocabulary.
• Limitations and interferences: Notes that dissolved colouring substances and surface reflections (wind/light conditions) can affect results.

Practical applications and users

• Environmental monitoring teams performing water quality and turbidity surveys.
• Laboratories needing a semi‑quantitative alternative to nephelometric/optical turbidimeter methods.
• Marine and limnology researchers using Secchi‑type data to estimate light penetration and trophic conditions.
• Bathing water and wastewater managers for routine transparency checks.
• Diving teams and monitoring programs that assess underwater visibility for ecological surveys or safety.

Related standards

• ISO 7027-1:2016 - Quantitative methods using optical turbidimeters and nephelometers (complements Part 2).
• CIE S 017/E - International lighting vocabulary (normative reference used in the standard).

EN ISO 7027-2:2019 is a practical standard for organisations that need repeatable, field‑capable transparency assessments to inform water quality management, ecological studies and regulatory monitoring. Keywords: EN ISO 7027-2:2019, turbidity, transparency testing tube, Secchi disc, water quality monitoring, attenuation coefficient, semi-quantitative methods.

Standards Content (Sample)

SLOVENSKI STANDARD
01-maj-2019
1DGRPHãþD
SIST EN ISO 7027:2000
Kakovost vode - Ugotavljanje motnosti - 2. del: Semikvantitativne metode za
ocenjevanje prosojnosti vode (ISO 7027-2:2019)
Water quality - Determination of turbidity - Part 2: Semi-quantitative methods for the
assessment of transparency of waters (ISO 7027-2:2019)
Wasserbeschaffenheit - Bestimmung der Trübung - Teil 2: Semi-quantitative Verfahren
zur Beurteilung der Transparenz von Gewässern (ISO 7027-2:2019)
Qualité de l'eau - Détermination de la turbidité - Partie 2: Méthodes semi-quantitatives
pour l'évaluation de la transparence des eaux (ISO 7027-2:2019)
Ta slovenski standard je istoveten z: EN ISO 7027-2:2019
ICS:
13.060.60 Preiskava fizikalnih lastnosti Examination of physical
vode properties of water
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 7027-2
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2019
EUROPÄISCHE NORM
ICS 13.060.60 Supersedes EN ISO 7027:1999
English Version
Water quality - Determination of turbidity - Part 2: Semi-
quantitative methods for the assessment of transparency
of waters (ISO 7027-2:2019)
Qualité de l'eau - Détermination de la turbidité - Partie Wasserbeschaffenheit - Bestimmung der Trübung - Teil
2: Méthodes semi-quantitatives pour l'évaluation de la 2: Semi-quantitative Verfahren zur Beurteilung der
transparence des eaux (ISO 7027-2:2019) Transparenz von Gewässern (ISO 7027-2:2019)
This European Standard was approved by CEN on 6 January 2019.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2019 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7027-2:2019 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 7027-2:2019) has been prepared by Technical Committee ISO/TC 147 "Water
quality" in collaboration with Technical Committee CEN/TC 230 “Water analysis” the secretariat of
which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by August 2019, and conflicting national standards shall
be withdrawn at the latest by August 2019.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 7027:1999.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 7027-2:2019 has been approved by CEN as EN ISO 7027-2:2019 without any
modification.
INTERNATIONAL ISO
STANDARD 7027-2
First edition
2019-01
Water quality — Determination of
turbidity —
Part 2:
Semi-quantitative methods for the
assessment of transparency of waters
Qualité de l'eau — Détermination de la turbidité —
Partie 2: Méthodes semi-quantitatives pour l'évaluation de la
transparence des eaux
Reference number
ISO 7027-2:2019(E)
©
ISO 2019
ISO 7027-2:2019(E)
© ISO 2019
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
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CH-1214 Vernier, Geneva
Phone: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2019 – All rights reserved

ISO 7027-2:2019(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Laboratory . 2
4.1 General . 2
4.2 Measurement using the transparency testing tube . 2
4.2.1 Apparatus . 2
4.2.2 Sampling and samples. 2
4.2.3 Procedure . 3
4.2.4 Expression of results . 3
5 In situ methods (field methods) . 3
5.1 General . 3
5.2 Measurement using the transparency testing disc . 3
5.2.1 Apparatus . 3
5.2.2 Procedure . 4
5.2.3 Expression of results . 5
5.2.4 Estimation of the attenuation coefficient (in the marine environment) . 5
5.3 Determination of visibility by divers . 5
5.3.1 Apparatus . 5
5.3.2 Procedure . 6
5.3.3 Expression of results . 6
6 Test report . 6
Annex A (informative) Devices . 8
Annex B (informative) Interlaboratory field study results .10
Bibliography .12
ISO 7027-2:2019(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
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different types of ISO documents should be noted. This document was drafted in accordance with the
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Attention is drawn to the possibility that some of the elements of this document may be the subject of
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URL: www .iso .org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 2,
Physical, chemical and biochemical methods.
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.
This first edition of ISO 7027-2, together with ISO 7027-1:2016, cancels and replaces ISO 7027:1999,
which has been technically revised.
A list of all parts in the ISO 7027 series can be found on the ISO website.
iv © ISO 2019 – All rights reserved

ISO 7027-2:2019(E)
Introduction
Turbidity in waters is caused by the presence of undissolved and/or colloidal matter and small
organisms (for example bacteria, phyto- and zooplankton) present in the water. Turbidity changes the
lighting conditions in surface waters by absorption and scattering of the light and thus influences the
trophic status of these waters. For the indicative assessment of the lighting conditions of waters or the
transparency of the water, semi-quantitative methods can be used (Reference [2]).
Measurements of transparency can be affected by the presence of dissolved light-absorbing substances
(substances imparting colour) as well as by particles (such as sediments).
In semi-quantitative methods such as the determination of transparency depth by Secchi disc,
reflections on the water surface can cause interferences. These are often dependent on the light and
wind conditions.
NOTE Results of a field study for the validation of this document is given in Annex B.
INTERNATIONAL STANDARD ISO 7027-2:2019(E)
Water quality — Determination of turbidity —
Part 2:
Semi-quantitative methods for the assessment of
transparency of waters
WARNING — Working in or around water is inherently dangerous. 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.
IMPORTANT — It is absolutely essential that tests conducted in accordance with this document
be carried out by suitably qualified and trained staff.
1 Scope
This document specifies the following semi-quantitative methods for the assessment of transparency
of waters:
a) measurement of visual range using the transparency testing tube (applicable to transparent and
slightly cloudy water), see Clause 4;
b) measurement of visual range in the upper water layers using the transparency testing disc
(especially applicable to surface, bathing water, waste water and often used in marine monitoring),
see 5.1;
c) measurement of visibility by divers in a destined depth, see 5.2.
NOTE The quantitative methods using optical turbidimeters or nephelometers are described in ISO 7027-1.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including amendments) applies.
CIE S 017/E, ILV: International Lighting Vocabulary
3 Terms and definitions
For the purposes of this document, the terms and definitions given in CIE S 017 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org ./obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1
transparency
permeability with respect to electromagnetic waves, here especially of light
Note 1 to entry: In this document, transparency is used in terms of visibility in waters.
ISO 7027-2:2019(E)
3.2
turbidity
reduction of transparency of a liquid caused by the presence of undissolved and/or colloidal matter and
small organi
...