oSIST prEN 18268:2026

• Abstract:

  This document is applicable to citric acid used as an antiscalant for membranes in the treatment of water intended for human consumption. It describes the characteristics and specifies the requirements and the corresponding analytical methods for citric acid. It gives information on its use as an antiscalant for membranes in water treatment.; General information on citric acid is given in Annex A (informative).

• Status: Not Published
• Public Enquiry End Date: 19-Jan-2026
• ICS: 13.060.20 - Drinking water
• ICS: 71.100.80 - Chemicals for purification of water
• Technical Committee: IOVO - Water supply and waste water engineering
• Current Stage: 4020 - Public enquire (PE) (Adopted Project)
• Start Date: 20-Nov-2025
• Due Date: 09-Apr-2026
• Completion Date: 20-Jan-2026
• Ref Project: FprEN 18268 - Chemicals used for treatment of water intended for human consumption - Antiscalants for membranes - Citric Acid

Overview

oSIST prEN 18268:2026 is a draft European Standard developed by CEN, specifying the requirements for citric acid used as an antiscalant in membrane water treatment processes, especially for water intended for human consumption. The standard outlines product characteristics, purity criteria, analytical test methods, delivery forms, safety, and handling guidelines. This document is relevant for producers, suppliers, water treatment professionals, and regulatory authorities concerned with chemicals for purification of drinking water using membrane technology.

Key Topics

• Citric Acid for Membrane Protection: Focuses on the use of citric acid to prevent or remove scale and fouling in membrane-based water treatment, such as reverse osmosis (RO) systems.
• Product Forms: Covers solid (anhydrous and monohydrate) and liquid citric acid; liquid products typically contain at least 45% citric acid.
• Purity Criteria: Sets minimum purity requirements, including limits for metallic and non-metallic impurities, to ensure safety and efficacy in water treatment applications.
• Analytical Methods: Details standardized procedures for sampling, testing citric acid content, and determining impurity levels, referencing international methods and standards.
• Safety and Handling: Provides guidance on safe handling, storage, labelling, and emergency procedures according to EU regulations.
• Regulatory Compliance: Offers information on relevant EU directives and national regulations which govern the use of chemicals in drinking water treatment.

Applications

Citric acid serves as a critical antiscalant and cleaning agent for maintaining high performance in membrane water treatment systems:

• Reverse Osmosis (RO) and Membrane Systems: Used as an offline cleaner and occasional antiscalant to remove mineral scale and organic fouling, prolonging membrane lifespan and ensuring safe drinking water quality.
• Dosage and Application: Typically applied as a dilute solution (1-3% for cleaning), though lower continuous dosages (1-20 mg/L) may be recommended for scale prevention. Dosage specifics should follow membrane manufacturer recommendations and system requirements.
• Safe Water Production: By adhering to the requirements in oSIST prEN 18268:2026, treatment operators can ensure that only suitable, high-purity citric acid is used, reducing the risk of introducing harmful impurities into potable water supplies.
• Industry and Municipal Use: The standard applies to both municipal drinking water plants and industrial facilities using membrane technology for potable water production.

Related Standards

To ensure comprehensive quality and safety in water treatment, oSIST prEN 18268:2026 should be used alongside the following key standards and regulations:

• EN 1233: Water quality - Determination of chromium by atomic absorption spectrometry.
• EN ISO 3696: Water for analytical laboratory use - Specification and test methods.
• EN ISO 5961: Water quality - Determination of cadmium by atomic absorption spectrometry.
• ISO 3165, ISO 6206, ISO 8213: Sampling techniques for chemical water treatment products.
• EU Regulation (EC) No 1272/2008: Classification, labelling, and packaging of chemical substances.
• Directive (EU) 2020/2184: Quality of water intended for human consumption.
• Membrane Manufacturer Guidelines: Specific dosing and cleaning instructions.

For water treatment professionals, compliance with oSIST prEN 18268:2026 enhances operational reliability, regulatory adherence, and public health protection through clearly defined specifications for citric acid as an antiscalant for membranes in drinking water systems.

SLOVENSKI STANDARD
01-januar-2026
Kemikalije, ki se uporabljajo za pripravo pitne vode - Sredstva proti apnencu na
membranah - Citronska kislina
Chemicals used for treatment of water intended for human consumption - Antiscalants
for membranes - Citric Acid
Produkte zur Aufbereitung von Wasser für den menschlichen Gebrauch - Antikalkmittel
für Membranen - Zitronensäure
Produits chimiques utilisés pour le traitement de l’eau destinée à la consommation
humaine - Produits antitartres pour membranes - acide citrique
Ta slovenski standard je istoveten z: prEN 18268
ICS:
13.060.20 Pitna voda Drinking water
71.100.80 Kemikalije za čiščenje vode Chemicals for purification of
water
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
EUROPEAN STANDARD
prEN 18268
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2025
ICS 71.100.80
English Version
Chemicals used for treatment of water intended for human
consumption - Antiscalants for membranes - Citric Acid
Produits chimiques utilisés pour le traitement de l'eau Produkte zur Aufbereitung von Wasser für den
destinée à la consommation humaine - Produits menschlichen Gebrauch - Antikalkmittel für
antitartres pour membranes - acide citrique Membranen - Zitronensäure
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee
CEN/TC 164.
If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
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.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a European Standard.

EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 18268:2025 E
worldwide for CEN national Members.

prEN 18268:2025(E)
Contents Page
European foreword . 4
Introduction . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Description . 6
4.1 Identification . 6
4.1.1 Chemical name . 6
4.1.2 Synonym or common names . 6
4.1.3 Relative molecular mass . 7
4.1.4 Empirical formula . 7
4.1.5 Chemical formula . 7
4.1.6 CAS Registry Number) . 7
4.1.7 EINECS reference) . 7
4.2 Commercial forms . 7
4.3 Physical properties . 7
4.3.1 Appearance . 7
4.3.2 Density . 7
4.3.3 Solubility in water . 8
4.3.4 Vapour pressure . 8
4.3.5 Boiling point at 100 kPa) . 8
4.3.6 Melting point . 8
4.3.7 Specific heat . 8
4.3.8 Viscosity (dynamic) . 8
4.3.9 Critical temperature . 8
4.3.10 Critical pressure . 8
4.3.11 Physical hardness . 8
4.4 Chemical properties . 8
5 Purity criteria . 8
5.1 General. 8
5.2 Composition if commercial product . 9
5.3 Impurities and main by-products . 9
5.4 Chemical parameters. 10
6 Test methods . 10
6.1 Sampling . 10
6.1.1 General. 10
6.1.2 Liquid . 10
6.2 Analyses. 11
6.2.1 Citric Acid content (main product) - General . 11
6.2.2 Impurities . 11
6.2.3 Chemical parameters. 12
7 Labelling - Transportation – Storage . 13
7.1 Means of delivery . 13
prEN 18268:2025 (E)
7.2 Risk and safety labelling according to the EU legislation[2]) . 14
7.3 Transportation regulations and labelling . 14
7.4 Marking . 14
7.5 Storage . 14
7.5.1 Material . 14
7.5.2 Long term stability . 14
7.5.3 Storage incompatibilities . 14
Annex A (informative) General information on citric acid . 15
Annex B (normative) General rules relating to safety . 17
Bibliography . 18

prEN 18268:2025(E)
European foreword
This document (prEN 18268:2025) has been prepared by Technical Committee CEN/TC 164 “Water
Supply”, the secretariat of which is held by AFNOR.
This document is currently submitted to the CEN Enquiry.
prEN 18268:2025 (E)
Introduction
In respect of potential adverse effects on the quality of water intended for human consumption, caused
by the products covered by this document:
a) this document provides no information as to whether the products may be used without restriction
in any of the Member States of the EU or EFTA;
b) it should be noted that, while awaiting the adoption of verifiable European criteria, existing national
regulations concerning the use and/or the characteristics of these products remain in force.
NOTE 1 Conformity with this document does not confer or imply acceptance or approval of the products in any
of the Member States of the EU, EFTA, or other European countries that are part of CEN.
The use of the product covered by this document is subject to regulation or control by National
Authorities.
NOTE 2 Attention is also drawn to citric acid products used as food additives meeting the high purity requirements
[3].
of E330 citric acid
WARNING – The use of this document may involve hazardous materials, operations and equipment. This
document does not purport to address all the safety problems associated with its use. It is the
responsibility of the user of this document to establish appropriate safety and health practices and
determine the applicability of regulatory limitations prior to use.
prEN 18268:2025(E)
1 Scope
This document is applicable to citric acid used as an antiscalant for membranes in the treatment of water
intended for human consumption. It describes the characteristics and specifies the requirements and the
corresponding analytical methods for citric acid. It gives information on its use as an antiscalant for
membranes in water treatment. It also provides guidance relating to safe handling and use (see Annex B).
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are
indispensable for its application. For dated references, only the edition cited applies. For undated
references, the latest edition of the referenced document (including any amendments) applies.
EN 1233, Water quality — Determination of chromium — Atomic absorption spectrometric methods
EN ISO 3696, Water for analytical laboratory use - Specification and test methods (ISO 3696)
EN ISO 5961, Water quality - Determination of cadmium by atomic absorption spectrometry (ISO 5961)
EN ISO 11885, Water quality - Determination of selected elements by inductively coupled plasma optical
emission spectrometry (ICP-OES) (ISO 11885)
EN ISO 12846, Water quality - Determination of mercury - Method using atomic absorption spectrometry
(AAS) with and without enrichment (ISO 12846)
ISO 3165, Sampling of chemical products for industrial use — Safety in sampling
ISO 6206, Chemical products for industrial use — Sampling — Vocabulary
ISO 8213, Chemical products for industrial use — Sampling techniques — Solid chemical products in the
form of particles varying from powders to coarse lumps
ISO 8288:1986, Water quality — Determination of cobalt, nickel, copper, zinc, cadmium and lead — Flame
atomic absorption spectrometric methods
ISO/TS 17379-2, Water quality — Determination of selenium — Part 2: Method using hydride generation
atomic absorption spectrometry (HG-AAS)
3 Terms and definitions
No terms and definitions are listed in this document.
4 Description
4.1 Identification
4.1.1 Chemical name
2-hydroxypropane-1,2,3-tricarboxylic acid
4.1.2 Synonym or common names
Citric Acid
Citric Acid Anhydrous
prEN 18268:2025 (E)
Citric Acid Monohydrate
4.1.3 Relative molecular mass
Citric Acid Anhydrous: 192,12
Citric Acid Monohydrate: 210,14
4.1.4 Empirical formula
C H O
6 8 7
C H O .H O
6 8 7 2
4.1.5 Chemical formula
C H O
6 8 7
Figure 1 — Chemical formula
4.1.6 CAS Registry Number )
Citric Acid Anhydrous 77-92-9
Citric Acid Monohydrate: 5949-29-1
4.1.7 EINECS reference )
Citric Acid Anhydrous 201-069-1
Citric Acid Monohydrate 691-328-9
4.2 Commercial forms
Citric Acid is available in a number of different forms (see 4.3.1).
Different commercial forms, anhydrous solids, monohydrate solid or dissolved in water are possible.
Commercial, stable aqueous solutions are available at a minimum 45 % weight/weight Citric Acid. All
concentrations mentioned refer to the active matter (active acid) and shall be calculated accordingly.
4.3 Physical properties
4.3.1 Appearance
Solid: The product is a colourless / white powder or crystalline granulate.
Liquid: The product is a clear, colourless solution.
4.3.2 Density
Solid: The bulk density of the product varies from 750 g/dm3 to 900 g/dm3.
...