ISO 12439:2025

International
Standard
ISO 12439
Second edition
Mixing water for concrete
2025-03
Eau de gâchage pour béton
Reference number
© ISO 2025
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Published in Switzerland
ii
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Requirements . 2
4.1 General .2
4.2 Preliminary assessment .2
4.3 Chemical properties . .3
4.3.1 Chlorides .3
4.3.2 Sulfates .3
4.3.3 Alkali .3
4.3.4 Harmful contamination .3
4.4 Setting time and strength . .4
5 Sampling . 4
6 Testing. 4
6.1 Test methods .4
6.1.1 Preliminary assessment .4
6.1.2 Humic matter .5
6.1.3 Chemical tests .5
6.1.4 Setting time and strength .5
6.2 Frequency for testing .6
6.3 Conformity evaluation .6
7 Test report . 6
Annex A (normative) Requirements for the use of water recovered from processes in the
concrete industry . 7
Annex B (informative) Testing scheme for mixing water for concrete .10
Annex C (informative) Recommended test methods.13
Annex D (informative) Requirements for radioactivity . 14
Bibliography .15

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
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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
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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 71, Concrete, reinforced concrete and pre-
stressed concrete, Subcommittee SC 3, Concrete production and execution of concrete structures.
This second edition cancels and replaces the first edition (ISO 12439:2010), which has been technically
revised.
The main changes are as follows:
— addition of some new normative references;
— addition of the definition of water types;
— inclusion of requirements regarding radioactive testing (subclause 4.3.4).
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
The quality of the mixing water for production of concrete can influence the setting time, the strength
development of concrete and the protection of the reinforcement against corrosion.
When assessing the suitability of water of unknown quality for the production of concrete, both the
composition of the water and the application of the concrete being produced must be considered.

v
International Standard ISO 12439:2025(en)
Mixing water for concrete
1 Scope
This document specifies requirements for the treatment of water that is suitable for making concrete in
accordance with ISO 22965 (all parts) and describes methods for assessing its suitability.
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 1920-3, Testing of concrete — Part 3: Making and curing test specimens
ISO 1920-4, Testing of concrete — Part 4: Strength of hardened concrete
ISO 23696-1, Water quality — Determination of nitrate in water using small-scale sealed tubes — Part 1:
Dimethylphenol colour reaction
ISO 6878, Water quality — Determination of phosphorus — Ammonium molybdate spectrometric method
ISO 13163, Water quality — Lead-210 — Test method using liquid scintillation counting
ISO 29581-1, Cement — Test methods — Part 1: Analysis by wet chemistry
ISO 9597, Cement — Test methods — Determination of setting time and soundness
ISO 22965-2, Concrete — Part 2: Specification of constituent materials, production of concrete and compliance
of concrete
ISO 10523, Water quality — Determination of pH
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
potable water
water intended for human consumption
Note 1 to entry: This water is generally considered as suitable for use in concrete. The water shall not be further
tested, if already tested and certified by concerned authorities. Otherwise, the water shall be tested and shall conform
to the requirements specified in 4.3.

3.2
natural surface water
water which flows over, or rests on, the surface of a land mass
Note 1 to entry: This water can be suitable for use in concrete but shall be tested to determine whether it is suitable
for use in concrete.
3.3
sewage water
wastewater conveyed in underground pipes
Note 1 to entry: This water is not suitable for use in concrete.
3.4
combined water
mixture of water recovered from processes in the concrete industry and water of some other origin.
Note 1 to entry: This water can be suitable for use in concrete but shall be tested to determine whether it is suitable
for use in concrete.
4 Requirements
4.1 General
Water for use in concrete shall conform to 4.2, 4.3.1, 4.3.2 and 4.3.3. The water shall conform to either the
chemical requirements in 4.3.4, or the requirements for setting time and compressive strength in 4.4.
NOTE When waters are mixed (see 3.4), the requirements apply to the combined water.
4.2 Preliminary assessment
The water shall be examined in accordance with the test procedures stated in Table 1. Water not in
accordance with one or more of the requirements in Table 1 may be used only if it can be shown to be suitable
for use in concrete in accordance with 4.4.
Table 1 — Requirements and test procedures for preliminary assessment of mixing water
Number Parameter Requirement Test procedure
1 Oils and fats Not more than visible traces. 6.1.1
2 Detergents Foam shall disappear within 2 min except for 6.1.1
small residues.
3 Colour Water not from sources classified as potable:
the colour shall be assessed qualitatively as pale 6.1.1
yellow or paler.
4 Suspended Water from sources classified as potable. A.4.4
matter
Water from other sources: max. 4 ml of sediment. 6.1.1
5 Odour Water from sources classified as potable: no smell,
except the odour allowed for potable water and a
slight smell of cement; where blast-furnace slag
is present in the water, a slight smell of hydrogen
6.1.1
sulfide.
Water from other sources: no smell, except the
odour allowed for potable water; no smell of hy-
drogen sulfide after addition of hydrochloric acid.
6 pH value pH ≥5 6.1.1
7 Humic mat- The colour shall be assessed qualitatively as yel-
6.1.2
ter lowish brown or paler after addition of NaOH.

4.3 Chemical properties
4.3.1 Chlorides
−
The chloride content of the water, tested in accordance with 6.1.3 and expressed as Cl , shall not exceed the
levels given in Table 2, unless it can be shown that the chloride content of the concrete does not exceed the
maximum value permitted for the total chloride content specified in ISO 22965-2.
ISO 22965-2 recommends that limits for the total chloride content in concrete be given in a national annex
to ISO 22965-2. The values may be different depending on the end use. It can be necessary to amend the
recommended values in Table 2 to fit with the limits for the total chloride content.
Table 2 — Maximum recommended values for the chloride content of mixing water
Chloride concentration
Test proce-
End use
dure
max. mg/l
Pre-stressed concrete or grout 500
Concrete with reinforcement or embedded metal 1 000 6.1.3
Concrete without reinforcement or embedded metal 4 500
4.3.2 Sulfates
2-
The sulfate content of the water, tested in accordance with 6.1.3 and expressed as SO shall not exceed
2 000 mg/l.
4.3.3 Alkali
If it is expected to use alkali-reactive aggregates in the concrete and the exposure conditions of the concrete
can promote deleterious alkali-related reactions to occur, the water shall be tested for its alkali content in
accordance with 6.1.3. The equivalent sodium oxide content of the water shall not exceed 1 500 mg/l, unless
it can be shown that the alkali content of the concrete does not exceed the maximum value recommended.
If these limits are exceeded, the water may be used only if it can be shown that actions have been taken to
prevent deleterious alkali-silica reactions.
NOTE Guidance can be found in technical literature, such as CEN CR 1901.
4.3.4 Harmful contamination
In the first instance, qualitative tests for sugars, phosphates, nitrates, lead and zinc may be carried out. If the
qualitative tests show a positive result, tests for setting time and compressive strength shall be performed
or chemical analysis shall be chosen.
If chemical analysis is chosen, the water shall conform to the limits given in Table 3.
When specified, the radioactivity of the water may be tested. See additional information in Annex D.
Table 3 — Requirements for harmful substances
Maximum concentration
Substance Test procedure
mg/l
Sugars 100
Phosphates; expressed as P O 100
2 5
−
6.1.3
Nitrates; expressed as NO
2+
Lead; expressed as Pb 100
2+
Zinc; expressed as Zn 100
4.4 Setting time and strength
When tested in accordance with 6.1.4, the initial setting time obtained on paste samples made with the
water shall be not less than 1 h and not differ by more than 25 % from the initial setting time obtained on
specimens made with distilled or de-ionized water. The final setting time shall not exceed 10 h and not differ
by more than 25 % from the final setting time obtained on specimens made with distilled or de-ionized
water. Potable water may be used, provided it has been demonstrated that it gives results similar to those
obtained with distilled or de-ionized water.
The mean compressive strength at 7 days and 28 days of the concrete or mortar specimens prepared with
the water shall be at least 90 % of the mean compressive strength of corresponding specimens prepared
with distilled or de-ionized water.
5 Sampling
A sample of water of not less than 5 l shall be taken. The sample shall be correctly identified. It shall be
representative of the water being used, with due regard being given to the possible effects of seasonal
fluctuations.
Natural surface water shall be collected from the centre of the water area and below 100 mm from the water
surface. The water from underground sources
...