FprEN 1278

Chemicals used for treatment of water intended for human consumption - Ozone

This document is applicable to ozone used for treatment of water intended for human consumption. It describes the characteristics of ozone, specifies tests methods for determining the ozone concentration in gases and determines rules for safe handling of the chemical ozone.

Produkte zur Aufbereitung von Wasser für den menschlichen Gebrauch - Ozon

Dieses Dokument gilt für Ozon zur Aufbereitung von Wasser für den menschlichen Gebrauch. Es beschreibt die Eigenschaften von Ozon und legt Prüfverfahren zur Bestimmung der Ozonkonzentration in anderen Gasen sowie Regeln für die sichere Handhabung der Chemikalie Ozon fest.

Produits chimiques utilisés pour le traitement de l'eau destinée à la consommation humaine - Ozone

Le présent document est applicable à l’ozone utilisé pour le traitement de l’eau destinée à la consommation humaine. Il décrit les caractéristiques de l’ozone, spécifie les méthodes d’essai pour la détermination de la concentration en ozone dans les gaz et détermine les règles pour la manipulation en toute sécurité de l’ozone chimique.

Kemikalije, ki se uporabljajo za pripravo pitne vode - Ozon

General Information

• Status: Not Published
• Publication Date: 19-Aug-2026
• ICS: 71.100.80 - Chemicals for purification of water
• Technical Committee: CEN/TC 164 - Water supply
• Drafting Committee: CEN/TC 164/WG 9 - Drinking water treatment
• Current Stage: 5020 - Submission to Vote - Formal Approval
• Start Date: 30-Apr-2026
• Due Date: 09-Feb-2026
• Completion Date: 30-Apr-2026
• Ref Project: kSIST FprEN 1278:2026 - Chemicals used for treatment of water intended for human consumption - Ozone

Relations

• Revises: EN 1278:2010 - Chemicals used for treatment of water intended for human consumption - Ozone
• Effective Date: 29-Jun-2022

Overview

FprEN 1278 is a European standard developed by CEN, specifying requirements for ozone used in the treatment of water intended for human consumption. This document covers the characteristics of ozone, testing methods for determining ozone concentration in gases, and the rules for safe handling and application. Ozone, as a powerful oxidant and disinfectant, plays a vital role in the purification and disinfection processes within the drinking water treatment sector.

This standard is crucial for water treatment professionals, utility operators, device manufacturers, and regulators seeking to ensure the safety, quality, and compliance of ozone applications in water treatment. It also aligns with EU regulatory frameworks such as REACH and the Biocidal Products Regulation (BPR), clarifying the use and authorization pathways for ozone.

Key Topics

• Ozone Characteristics:

  • Chemical name: Ozone (O₃)
  • CAS Registry Number: 10028-15-6
  • Highly unstable and generated on-site
  • Powerful oxidizer and disinfectant
  • Physical properties include bluish color, high reactivity, and gaseous form at ambient conditions

• Test Methods:

  • Determination of ozone concentration in gases via titration or UV-absorption (referenced through FprEN 17971)
  • Methods for monitoring ozone in water and process gas, including safety and performance checks

• Purity Criteria:

  • Purity of ozone gas is dependent on feed gas quality (clean dry air or oxygen) and generation technology
  • Purity requirements reference FprEN 17971
  • No relevant pesticides or polycyclic aromatic hydrocarbons are introduced as by-products

• Safe Handling:

  • Ozone is toxic by inhalation-strict controls and closed systems are required
  • Safety classifications and risk statements based on EU CLP Regulation
  • Handling requires adherence to strict safety procedures, personal protective equipment, and emergency guidelines

• Regulatory Frameworks:

  • Disinfection uses fall under the EU Biocidal Products Regulation (BPR)
  • Oxidative (non-biocidal) uses are addressed under REACH

Applications

Ozone is applied in various stages of water treatment for functions including:

• Disinfection:

  • Effective against bacteria, viruses, and parasites
  • Supports compliance with stringent microbial safety standards

• Removal of Pollutants:

  • Oxidation of organic pollutants, color, taste, and odor issues
  • Removal of metals such as iron and manganese

• Advanced Oxidation Processes (AOPs):

  • Used with hydrogen peroxide, UV, or catalysts for persistent pollutants
  • Supports modern water treatment solutions for emerging contaminants

• Coagulation Aid:

  • Promotes the coagulation of dissolved substances
  • Enhances overall treatment efficiency

Ozone is generated and applied on-site as its unstable nature prevents transport or storage. Dose and technology selection depend on source water quality and treatment goals, requiring professional assessment and operational control.

Related Standards

For comprehensive ozone application and system compliance, refer to these connected standards and regulations:

• FprEN 17971: Focuses on devices for in-situ generation of biocides (ozone), including operational safety and device-specific requirements
• EN ISO 3696: Pertains to water for analytical laboratory use
• Regulation (EU) No 528/2012 (BPR): Addresses biocidal product authorization for ozone disinfection
• Regulation (EC) No 1907/2006 (REACH): Covers registration and authorization for oxidative uses
• Directive (EU) 2020/2184: Sets the requirements for the quality of water intended for human consumption

By following FprEN 1278, organizations ensure safe, effective, and compliant ozone use in potable water treatment, safeguarding public health and meeting European regulatory standards.

Standards Content (Sample)

SLOVENSKI STANDARD
oSIST prEN 1278:2024
01-julij-2024
Kemikalije, ki se uporabljajo za pripravo pitne vode - Ozon
Chemicals used for treatment of water intended for human consumption - Ozone
Produkte zur Aufbereitung von Wasser für den menschlichen Gebrauch - Ozon
Produits chimiques utilisés pour le traitement de l'eau destinée à la consommation
humaine - Ozone
Ta slovenski standard je istoveten z: prEN 1278
ICS:
13.060.20 Pitna voda Drinking water
71.100.80 Kemikalije za čiščenje vode Chemicals for purification of
water
oSIST prEN 1278:2024 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

oSIST prEN 1278:2024
oSIST prEN 1278:2024
DRAFT
EUROPEAN STANDARD
prEN 1278
NORME EUROPÉENNE
EUROPÄISCHE NORM
May 2024
ICS 71.100.80 Will supersede EN 1278:2010
English Version
Chemicals used for treatment of water intended for human
consumption - Ozone
Produits chimiques utilisés pour le traitement de l'eau Produkte zur Aufbereitung von Wasser für den
destinée à la consommation humaine - Ozone menschlichen Gebrauch - Ozon
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
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 1278:2024 E
worldwide for CEN national Members.

oSIST prEN 1278:2024
prEN 1278:2024 (E)
Contents Page
European foreword . 3
Introduction . 4
1 Scope . 5
2 Normative references . 5
3 Terms and definitions . 5
4 Description . 5
4.1 Identification . 5
4.2 Commercial form . 6
4.3 Physical properties . 6
4.4 Chemical properties . 8
5 Purity criteria . 8
5.1 General. 8
5.2 Composition of in situ generated Ozone gas . 8
5.3 Impurities and main by-products . 9
5.4 Chemical parameters. 9
6 Test methods . 9
7 Labelling - Transportation – Storage . 9
7.1 Materials in contact with Ozone . 9
7.2 Risk and safety classification . 9
7.3 Transportation regulations and labelling . 10
7.4 Marking . 11
7.5 Stability . 11
Annex A (informative)  General information on ozone . 12
A.1 Feed gas . 12
A.2 Use . 12
A.3 Operational control methods . 13
Annex B (normative) General rules relating to safety . 16
B.1 Rules for safe handling and use . 16
B.2 Emergency procedures . 16
Bibliography . 18

oSIST prEN 1278:2024
prEN 1278:2024 (E)
European foreword
This document (prEN 1278:2024) 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.
This document will supersede EN 1278:2010.
prEN 1278:2024 includes the following significant technical changes with respect to EN 1278:2010:
— proposed harmonized classification of ozone according to EU CLP regulation is added;
— reference for use of ozone is made to EU BPR and EU REACH regulation;
— new threshold limit for ozone in air;
— reference is made to FprEN 17971, standard for ozone generation devices. Device related matters
are shifted to FprEN 17971, e.g. operational safety of the installation room. Matters of the chemical
ozone itself remain within this standard.
oSIST prEN 1278:2024
prEN 1278:2024 (E)
Introduction
In respect of potential adverse effects on the quality of water intended for human consumption, caused
by the product covered by this document, it provides no information as to whether the product may be
used without restriction in any of the Member States of the EU or EFTA.
NOTE 1 While awaiting the adoption of verifiable European criteria, attention is drawn to national regulations.
Ozone is a biocidal product according to the regulation (EU) No 528/2012 [1]. The use of in situ generated
ozone for disinfection purposes falls under the provisions of the BPR, requiring access by the user to a
data set for the product authorization of ozone under the BPR. This access may be achieved directly or
indirectly e.g. via the manufacturers’ authorization for ozone generated by their devices.
Users of in situ generated ozone should verify with their device manufacturer, if they can use ozone in
accordance to his product authorization for the disinfection of water intended for human consumption
(included in the BPR for drinking water use).
Non biocidal use of ozone, e.g. for oxidative purposes, falls under the provisions of the REACH Regulation
[2]. The use of ozone for non-biocidal purposes requires individual access by the user to the data set
provided for the authorization of ozone under REACH.
NOTE 2 Conformity with the standard does not confer or imply authorization of the product in any of the
Member States of the EU or EFTA. The use of the product covered by this document is subject to regulation or control
by National Authorities.
oSIST prEN 1278:2024
prEN 1278:2024 (E)
1 Scope
This document is applicable to ozone used for treatment of water intended for human consumption. It
describes the characteristics of ozone, specifies tests methods for determining the ozone concentration
in gases and determines rules for safe handling of the chemical ozone.
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.
FprEN 17971, Devices for in-situ generation of biocides — Ozone
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
normal temperature and pressure of gas
NTP
gas under the conditions of normal temperature tn = 0 °C and normal pressure pn = 101 325 Pa
3.2
feed gas
substance that is fed as gas to the ozone generation device to generate ozone
4 Description
4.1 Identification
4.1.1 chemical name
Ozone.
General information on Ozone is described in Annex A.
4.1.2 synonym or common name
None (has sometimes been called improperly “allotropic oxygen”).
4.1.3 relative molecular mass
48.
4.1.4 Empirical formula
O
3.
4.1.5 chemical formula
O
3.
oSIST prEN 1278:2024
prEN 1278:2024 (E)
1)
4.1.6 CAS Registry Number
10028-15-6.
2)
4.1.7 EINECS reference
Not applicable.
4.2 Commercial form
Ozone is very unstable; it is exclusively generated on-site nearby its use by ozone generation devices.
4.3 Physical properties
4.3.1 Appearance
Bluish gas, the liquid is dark blue.
NOTE A weak absorption in the visual range between 435 nm and 475 nm.
4.3.2 Density
Gas: 2,144 kg/m at NTP (Normal Temperature Pressure, 273 K and 1013,25 hPa);
Liquid: 1,574 g/cm at - 183 °C;
Solid: 1,728 g/cm .
4.3.3 The gas-liquid partition coefficient
In pure water, the partition coefficient values (S) expressed in grams per cubic meter water per (grams
per cubic meter) gas at 1013,25 hPa are given in Table 1.
Table 1 — The gas-liquid partition coefficient between water and gas phase
Temperature Solubility
of water
g / m HO
°C S, in
g / m gas
0 0,64
5 0,5
10 0,39
15 0,31
20 0,24
25 0,19
30 0,15
35 0,12
NOTE 1 Recent surveys of literature data are given in Bibliography. See [3], [4] and [5].
NOTE 2 S is a ratio, not an absolute concentration.

1)
Chemical Abstracts Service Registry Number
2)
European Inventory of Existing Commercial Chemical Substances
oSIST prEN 1278:2024
prEN 1278:2024 (E)
4.3.4 Vapour pressure
The vapour pressure of ozone depending on temperature is given in Table 2.
Table 2 — Vapour pressure
Temperature Vapour pressure
°C hPa
- 183 0,147
- 180 0,28
- 170 01,88
- 160 8,97
- 150 33,06
- 140 98,92
- 130 253,31
- 120 569,28
- 110 1153,22
- 100 2 1390,79
3)
4.3.5 Boiling point at 1000 hPa
− 112 °C.
NOTE Vaporization heat: 681 kJ/m3at NTP.
4.3.6 Melting point
− 196 °C.
4.3.7 Specific heat (liquid)
Not applicable.
4.3.8 Viscosity (dynamic)
0,004 2 Pa.s at – 195 °C;
0,0015 5 Pa.s at – 183 °C.
4.3.9 Critical temperature
− 12,1 °C.
4.3.10 Critical pressure
5 4600 hPa.
4.3.11 Physical hardness
Not applicable.
3)
1000 hPa = 1 bar
oSIST prEN 1278:2024
prEN 1278:2024 (E)
4.4 Chemical properties
Ozone is a powerful oxidant and disinfectant. The standard redox potentials (ORP) at 25 °C are:
H
( E values in volts):
O
H
+ - O + H O (1)
O + 2H + 2e → 2 2 = 2,07 V
E
O
H
- - (2)
O + H O + 2e → O + 2OH
E = 1,24 V
3 2 2
O
H
+ - H O (3)
OH° + H + e → 2
E = 2,42 V (calculated value)
O
H
If the pH increases by one unit, the E -values shall decrease by 30 mV per electron transferred. At
H
1000 hPa and 25 °C and pH = 7 the E -values, versus the normal hydrogen electrode, become:
O (1) = 1,66 V;
O3 (2) = 0,82 V;
OH° (3) = 2,21V
In water treatment most of the direct reactions of ozone are dipolar cyclo-additions and electrophilic
substitution reactions. Moreover ozone, in water, can generate radicals such as OH° in particular at
alkaline pH: (O + H O → 2 OH° + O ). The OH° radical is a strong general oxidant.
3 2 2
5 Purity criteria
5.1 General
The purity of the generated ozone depends strongly on the purity of the precursors and the technology
of the applied ozone generation device. The generation of ozone used for the treatment of water intended
for human consumption takes place usually by the technology of dielectric barrier discharge. This
technology uses ambient air or oxygen as feed gas for the ozone generation device to generate ozone. The
generation technology, purity requirements for the feed gas, by-products of the ozone generation, and by
products of ozone dosed in water are described in the FprEN 17971. The purity requirements of
FprEN 17971 apply for this standard.
NOTE Attention is drawn to national regulation for the users of Ozone in order to clarify whether it is of
appropriate purity for treatment of water intended for human consumption, taking into account raw water quality,
required dosage, contents of other impurities and additives used in the product not stated in this product document.
5.2 Composition of in situ generated Ozone gas
According to FprEN 17971 the nominal ozone concentration using:
3 3
— clean dry air is typically 20 g ozone per m n of process gas = ca. 1,5 % w/w (in practice 70 g/m n = ca.
5,3 % w/w can be achieved).
— oxygen as a feed gas is typically 100 g per m n of process gas = ca. 7 % w/w (in practice
300 g/m = ca. 21 % w/w can be achieved).
n
The concentration (in grams per cubic metre NTP) at the nominal operating condition of the generators
shall be specified in the tendering documents.
oSIST prEN 1278:2024
prEN 1278:2024 (E)
5.3 Impurities and main by-products
See A.3.2.
5.4 Chemical parameters
None of the chemical parameters according to the EU directive on the quality of water intended for human
consumption [7] are found in the gaseous ozone phase. Pesticides and polycyclic aromatic hydrocarbons
are not by-products of the ozone manufacturing processes.
NOTE For the purpose of this document “chemical parameters” are those defined in the EU directive on the
quality of water intended for human consumption [7].
6 Test methods
The test methods by titration and by UV-absorption are described in detail in the FprEN 17971.
7 Labelling - Transportation – Storage
7.1 Materials in conta
...