IEC TS 63429:2023

IEC TS 63429 ®
Edition 1.0 2023-09
TECHNICAL
SPECIFICATION
Washing machines for household use – Method for measuring the
microbiological performance
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IEC TS 63429 ®
Edition 1.0 2023-09
TECHNICAL
SPECIFICATION
Washing machines for household use – Method for measuring the

microbiological performance
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 97.060  ISBN 978-2-8322-7477-4

– 2 – IEC TS 63429:2023 © IEC 2023
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references . 7
3 Terms, definitions and symbols. 8
3.1 Terms and definitions . 8
3.2 Symbols . 9
4 Requirements . 9
5 Test conditions, materials, equipment and instrumentation . 10
5.1 Test conditions . 10
5.2 Materials and reagents . 10
5.2.1 Microorganisms for test purposes . 10
5.2.2 Culture media and solutions . 11
5.2.3 Detergent . 13
5.3 Equipment . 14
5.3.1 General . 14
5.3.2 Incubator . 14
5.3.3 Autoclave . 14
5.3.4 Cotton carrier . 14
5.3.5 Biomonitor cloth . 14
5.3.6 Pipettes . 15
5.3.7 Electromechanical agitator. 15
5.3.8 Base load . 15
5.3.9 Measuring equipment for assessing temperature profile . 16
5.3.10 Measuring equipment for water consumption . 16
6 Tests . 16
6.1 Test method principles . 16
6.2 Preparation of washing machine . 16
6.3 Preparation of test microorganisms and biomonitors . 17
6.3.1 Cultures . 17
6.3.2 Biomonitors . 18
6.4 Main test . 19
6.4.1 General . 19
6.4.2 Evidence of test microorganisms . 19
6.5 Validation . 20
6.5.1 Enumeration of microorganisms before washing N (reference
biomonitor) . 20
6.5.2 Negative control (cross contamination) . 21
6.5.3 Determination of water quality . 21
6.5.4 Determination of water quantity in the main wash . 21
7 Evaluation . 21
7.1 Log reduction . 21
7.2 Cross contamination . 21
8 Test report . 22
Annex A (normative) Suitable methods to prepare the washing machine prior to test . 24
A.1 General . 24

A.2 Methods to prepare the washing machines before test . 24
A.2.1 Hot washing with the detergent . 24
A.2.2 Hot washing without detergent . 24
A.2.3 Treatment with sodium hypochlorite solution . 24
A.2.4 Treatment with peracetic acid solution (PAA) . 25
Annex B (informative) Sources of materials and supplies . 26
B.1 General . 26
B.2 Suppliers for test materials . 26
Bibliography . 27

Figure 1 – Biomonitor cloth . 15

Table 1 – Composition of TSA . 11
Table 2 – Composition of Sabouraud dextrose agar with chloramphenicol . 11
Table 3 – Composition of Tryptic Soy Broth (TSB) . 12
Table 4 – Composition of Baird-Parker agar . 12
Table 5 – Composition of cetrimide agar . 12
Table 6 – Composition of diluting agent . 13
Table 7 – Composition of neutralisation solution . 13
Table 8 – Temperature logger specification . 16

– 4 – IEC TS 63429:2023 © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
WASHING MACHINES FOR HOUSEHOLD USE –
METHOD FOR MEASURING THE MICROBIOLOGICAL PERFORMANCE

FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international
co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and
in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,
Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with
may participate in this preparatory work. International, governmental and non-governmental organizations liaising
with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for
Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
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6) All users should ensure that they have the latest edition of this publication.
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8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent
rights. IEC shall not be held responsible for identifying any or all such patent rights.
IEC TS 63429 has been prepared by subcommittee 59D: Performance of household and similar
electrical laundry appliances, of IEC Technical Committee 59: Performance of household and
similar electrical appliances. It is a Technical Specification.
The text of this Technical Specification is based on the following documents:
Draft Report on voting
59D/498/DTS 59D/503A/RVDTS
Full information on the voting for its approval can be found in the report on voting indicated in
the above table.
The language used for the development of this Technical Specification is English.
In this document, the following print type is used:
– terms defined in Clause 3: bold type.

This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in
accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available
at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are
described in greater detail at www.iec.ch/publications.
The committee has decided that the contents of this document will remain unchanged until the
stability date indicated on the IEC website under webstore.iec.ch in the data related to the
specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
– 6 – IEC TS 63429:2023 © IEC 2023
INTRODUCTION
This Technical Specification describes a method to measure the microbial contamination
reduction performance of household washing machines. Microbial reduction due to any
potential or claimed antimicrobial action of detergents other than the base powder of the
required detergent, as well as of bleach systems or any other additives, is not addressed.
This first edition has been developed to provide a globally applicable and agreed method to
measure the reduction of the microbial contamination of household washing machines and
their programmes, to be measured with textile pieces contaminated with test microorganisms
under standardized conditions.
The reduction of the microbial contamination is just one of the performance parameters
measurable for a washing machine. Therefore, it is not used as the only parameter to describe
the performance of a washing programme, but it is measured along with the other performance
parameters considered for that programme.
NOTE The use of the reference washing machine as defined in IEC 60456 as a reference process for the reduction
of microbial contamination is under consideration.
The test microorganisms requested for this Technical Specification require BSL-1 and 2
laboratories. BSL-1 laboratories are restricted to the use of Staphylococcus arlettae and
Saccharomyces cerevisiae, whereas BSL-2 laboratories shall use Pseudomonas aeruginosa,
Staphylococcus aureus, Candida albicans, or all five test microorganisms.
Classification of test microorganisms can change and can differ on national levels. It is the
responsibility of the user to ensure compliance with applicable national classification.
Different type strains of the same microbial species described in this Technical Specification
can be used if the achievement of comparable results is proven.
Additional test microorganisms can be used besides the test strains described in this Technical
Specification, but their result cannot be used to claim compliance with the Technical
Specification and shall not be reported in the same test report.
The ATCC numbers are the collection numbers of strains supplied by the American Type Culture
Collections (ATCC). This information is given for the convenience of users of this Technical
Specification and does not constitute an endorsement by IEC of the product named.
This document does not purport to address all the safety aspects, if any, associated with its
use. It is the responsibility of the user to establish appropriate health and safety practices and
to ensure compliance with any national, regional or international regulatory conditions.
A warning about the use of this document is included in Clause 4.

WASHING MACHINES FOR HOUSEHOLD USE –
METHOD FOR MEASURING THE MICROBIOLOGICAL PERFORMANCE

1 Scope
This Technical Specification provides a test method for measuring the microbial contamination
reduction performance of household washing machines with textile pieces contaminated with
test microorganisms under standardized conditions. The microbial numbers on the
contaminated textile pieces are measured before and after the washing programme and the
reduction is calculated. Furthermore, a potential cross contamination from contaminated to
uncontaminated textile pieces within the washing programme is measured.
This document does not address the microbial contamination reduction due to any potential or
claimed antimicrobial action of detergents as well as of bleach systems or any additives.
This document applies to washing machines for household use, within the meaning that the
scope of TC 59 indicates for household use, including the washing related functions of washer-
dryers.
This document does not apply to professional washing machines nor to commercial laundry
operations associated with food service, hospital linens or other non-residential applications.
This document deals with measurement procedures regarding the reduction of microbial
contamination resulting from the use of electrical appliances for household and similar use. This
document specifies methods that enable reproducible measurements. These derived
measurement results can only be used for a relative statement. Absolute statements, i.e.,
health-related claims or conclusions about prevention or treatment of a disease or health
improvement, are reserved for explicit regulatory action after a medical assessment.
This document does not apply to appliances intended to be used in medical, veterinary, or
pharmaceutical applications.
This document does not address sanitization, disinfection, or sterilization measures.
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.
IEC 60456:2010, Clothes washing machines for household use – Methods for measuring the
performance
IEC 60456:2010/AMD1:2022
ISO 2267, Surface active agents – Evaluation of certain effects of laundering – Methods of
preparation and use of unsoiled cotton control cloth
ISO 19458:2006, Water quality – sampling for microbiological analysis
EN 12353, Chemical disinfectants and antiseptics. Preservation of test organisms used for the
determination of bactericidal (including Legionella), mycobactericidal, sporicidal, fungicidal and
virucidal (including bacteriophages) activity

– 8 – IEC TS 63429:2023 © IEC 2023
3 Terms, definitions and symbols
For the purposes of this document, the following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following
addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1 Terms and definitions
3.1.1
washing machine
appliance for cleaning and rinsing of textiles using water which may also have a means of
extracting excess water from the textiles
[SOURCE: IEC 60456:2010, 3.1.1]
3.1.2
test run
performance assessment of one programme execution in the test washing machine
3.1.3
test series
set of test runs which are collectively used to assess performance
[SOURCE: IEC 60456:2010, 3.1.12]
3.1.4
operation
each performance of a function that occurs during the washing machine programme such as
pre-wash, washing, rinsing, draining, or spinning
[SOURCE: IEC 60456:2010, 3.1.13]
3.1.5
programme
series of operations which are pre-defined within the washing machine, and which are
declared by the manufacturer as suitable for washing certain textile types for hygiene purposes
[SOURCE: IEC 60456:2010, 3.1.14, modified – "for hygiene purposes" has been added to the
end of the definition.]
3.1.6
cycle
complete washing process, as defined by the programme selected, consisting of a series of
operations (wash, rinse, spin, etc.) and including any operations that occur after the
completion of the programme
[SOURCE: IEC 60456:2010, 3.1.6, modified – The note has been omitted.]
3.1.7
base load
textile load used for testing without biomonitor cloths and biomonitors

3.1.8
cross contamination
transfer of microorganisms from contaminated fabrics to uncontaminated fabrics during one
test run
3.1.9
biomonitor
microorganism carrier inoculated with microorganisms to be used to monitor the reduction of
microbial contamination
3.1.10
biomonitor cloth
cotton cloth with six individual pockets that fixes biomonitors and temperature loggers during
a test run in a washing machine
3.1.11
temperature profile
time-temperature data representing the water temperature in the washing machine during the
test run
3.1.12
washer-dryer
washing machine which includes both a spin extraction function and also a means for drying
the textiles, usually by heating and tumbling
[SOURCE: IEC 60456:2010, 3.1.4, modified – The note has been omitted.]
3.2 Symbols
cfu colony forming unit
N average value of microorganism amount of the three positive controls, before
exposition to the test programme (cfu/biomonitor)
N average value of microorganism amount per 5 biomonitors, after exposition to
the test programme (cfu/biomonitor)
log(N /N) reduction factor per microorganism type
-1
v microorganism amount in a 10 times diluted solution
-2
v microorganism amount in a 100 times diluted solution
4 Requirements
This document specifies a test method for measuring the reduction of microbial contamination
in clothes washing machines and of possible cross contamination from contaminated
biomonitors to sterile cotton swatches.
This document does not specify safety requirements and does not deal with performance of
washing machines measured under IEC 60456 nor with effects on fabrics.
WARNING – The tests given in this document shall be performed by expert staff trained to
handle microorganism-related techniques and in properly equipped laboratories under the
supervision of a skilled microbiologist. Some of the test microorganisms can be facultative
pathogens for humans, animals and plants; their handling requires a laboratory of an
appropriate biosafety level. National and international safety procedures for working with
infectious biomaterials exist to prevent any contamination of laboratory staff, apparatus, the
workplace or the environment.
– 10 – IEC TS 63429:2023 © IEC 2023
5 Test conditions, materials, equipment and instrumentation
5.1 Test conditions
Ambient conditions: electricity supply, water supply, and ambient temperature shall be in
accordance with IEC 60456:2010. The base load shall be the cotton base load as specified in
IEC 60456:2010.
Hard water with a total water hardness of (2,5 ± 0,2) mmol/l or soft water with a total water
hardness of (0,5 ± 0,2) mmol/l as defined in IEC 60456 shall be used for testing.
The water supplied to the washing machine shall contain less than 100 cfu/ml total microbial
counts at an incubation temperature of 30 °C. Microorganisms for test purposes as listed in
5.2.1 should not be present in the supplied water. The water supplied to the washing machine
shall not contain more than 0,3 mg/l of chlorine.
When checking for the presence of microorganisms in the supplied water, the following shall be
considered: Staphylococcus aureus, Staphylococcus arlettae, Candida albicans,
Saccharomyces cerevisiae are normally not present in the water system and shall not be looked
for. Pseudomonas aeruginosa can be present in small numbers (< 10 Pseudomonas aeruginosa
counts per 100 ml), and at these levels does not significantly influence measurements in
accordance with this document.
The water supplied to the washing machine shall contain less than 10 cfu/100 ml
Pseudomonas aeruginosa. If higher numbers of Pseudomonas aeruginosa are detected,
measures to decontaminate the water system should be taken and tests should be repeated.
Water sampling shall be done in accordance with ISO 19458:2006, 4.4.1.3 as outlined for the
assessment of water quality in the main distributor. The water shall be sampled from the water
tap in the water system which is closest to the connecting valve of the washing machine. The
aerator and O-rings of the sampling point shall be removed, and the water tap disinfected. The
water tap shall be rinsed until water temperature is constant before sampling. Sampling volume
shall be 150,0 ml.
The microbiological quality of the water supplied to the washing machine is determined in
accordance with 6.5.3.
5.2 Materials and reagents
5.2.1 Microorganisms for test purposes
For test purposes, the following strains shall be used as test microorganisms:
• Pseudomonas aeruginosa ATCC 15442
• Staphylococcus aureus ATCC 6538
• Candida albicans ATCC 10231
NOTE 1 This combination of microorganisms can require a Biosafety Level 2 laboratory.
Alternative test microorganisms that can be used are:
• Staphylococcus arlettae ATCC 43957
• Saccharomyces cerevisiae ATCC 9763
NOTE 2 This combination of microorganisms can require a Biosafety Level 1 laboratory.
NOTE 3 The use of additional risk group 1 test microorganisms (e.g., Escherichia coli) is under consideration.

The three test microorganisms P. aeruginosa, S. aureus and C. albicans or the two test strains
S. arlettae and S. cerevisiae shall be used in a test series. The use of all five test
microorganisms in one test series is permitted.
NOTE 4 This combination of microorganisms can require a Biosafety Level 2 laboratory.
NOTE 5 For indications about possible suppliers of ready-to-use biomonitors, see Annex B.
5.2.2 Culture media and solutions
5.2.2.1 Culture media
5.2.2.1.1 General
All media and solutions shall be of microbiological grade and sterilized appropriately prior to
use. It is recommended to use commercially available or water-free dry materials for the culture
media. The specifications in 5.2.2.1.2 to 5.2.2.1.6 refer to water-free products.
5.2.2.1.2 Tryptone soy agar (TSA)
The composition of tryptone soy agar (TSA) shall be in accordance with Table 1.
Table 1 – Composition of TSA
Description Specification
Casein peptone (pancreatic digest) 15,0 g/l
Soy peptone (papaic digest) 5,0 g/l
Sodium chloride 5,0 g/l
Agar 15,0 g/l
Final pH 7,3 ± 0,2
5.2.2.1.3 Sabouraud dextrose agar with chloramphenicol
The composition of Sabouraud dextrose agar with chloramphenicol shall be in accordance with
Table 2.
Table 2 – Composition of Sabouraud dextrose agar with chloramphenicol
Description Specification
Pancreatic digest of casein 5,0 g/l
Peptic digest of animal tissue 5,0 g/l
Dextrose monohydrate 40,0 g/l
Chloramphenicol 0,05 g/l
Agar 15,0 g/l
Final pH 5,6 ± 0,2
5.2.2.1.4 Tryptic soy broth (TSB)
The composition of tryptic soy broth (TSB) shall be in accordance with Table 3.

– 12 – IEC TS 63429:2023 © IEC 2023
Table 3 – Composition of Tryptic Soy Broth (TSB)
Description Specification
Tryptone, pancreatic digest of casein 17,0 g/l
Soy peptone, papaic digest of soybean meal 3,0 g/l
Sodium chloride (NaCl) 5,0 g/l
Dipotassium hydrogen phosphate (K HPO ) 2,5 g/l
2 4
Glucose 2,5 g/l
Final pH 7,3 ± 0,2
5.2.2.1.5 Baird-Parker agar
The composition of Baird-Parker agar shall be in accordance with Table 4.
Table 4 – Composition of Baird-Parker agar
Description Specification
Tryptone 10,0 g/l
Beef extract 5,0 g/l
Yeast extract 1,0 g/l
Glycine 12,0 g/l
Sodium pyruvate 10,0 g/l
Lithium chloride 5,0 g/l
Agar 20,0 g/l
Final pH 6,8 ± 0,2
Autoclave the agar at 121 °C for 15 min. After cooling down to 50 °C, add aseptically 50,0 ml/l
of egg yolk tellurite emulsion.
5.2.2.1.6 Cetrimide agar
The composition of cetrimide agar shall be in accordance with Table 5.
Table 5 – Composition of cetrimide agar
Description Specification
Pancreatic digest of gelatine 20,0 g/l
Potassium sulphate 10,0 g/l
Magnesium chloride 1,4 g/l
Cetyltrimethylammonium chloride 0,3 g/l
Agar 13,6 g/l
Final pH 7,2 ± 0,2
Dissolve the components of the cetrimide agar in 1,0 L water, as specified in 5.2.2.2. Add
10,0 ml of glycerol and boil to dissolve completely. Autoclave the agar at 121 °C for 15 min.

5.2.2.2 Water for culture media and solutions
Bi-distilled or demineralised water may be used. However, water for culture media and solutions
shall be sterilized prior to use.
Sterilization is not required if the water will be used for preparation of culture me
...