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Water Quality Standards for CSD
A look at Australian, UK, ISO/EN, AAMI and WFHSS
standards and guidelines
QLD SRACA August 2014
Current AS 4187-2003

2.1 WATER QUALITY FOR CLEANING

“Tests should be conducted weekly on the hardness of the water, and
records kept.”

“High water hardness will leave a white-grey coloured residue on all
types of surfaces, which in the case of instruments will shorten their life
span. Water hardness also affects the activity of the detergent”
Current AS 4187-2003

2.1 WATER QUALITY FOR CLEANING

“Consideration should be given to the use of softened, filtered,
demineralized, or even distilled water in at least the final rinse stage of
the washing process and preferably all washing stages. Water
treatment, reverse osmosis or softening units should be selected having
regard to the total demand, volume and rate of treated/softened water
required in the instrument washing area. Water with high mineral
content is unsuitable for the rinsing of instruments due to mineral
deposits permanently damaging and seriously shortening the life of the
instruments.”
ISO 15883-1 Washer-disinfectors —Part 1:
General requirements, terms and definitions and tests

6.4.2 Quality of final rinse water

6.4.2.2 Tests for chemical purity

Tests for chemical purity shall include tests for those determinands
known to influence the efficacy of the process.

NOTE This can include, but is not limited to, tests to determine the
value of the following:
 ⎯ conductivity;
 ⎯ pH;
 ⎯ oxidizable substances [determined by the European Pharmacopoeia (EP) method or
as redox potential determined
 by the United States Pharmacopoeia (USP) method];
 ⎯ total hardness (salts of Ca2+, Mg2+, Sr2+ expressed as mmol CaCO3);
 ⎯ total dissolved solids (TDS) determined as evaporative residue;
 ⎯ inorganic phosphate [Pi] and inorganic silicate [SiO2], determined as the molybdate
reactive species;
 ⎯ chloride [Cl−
ISO 15883-1 Washer-disinfectors —Part 1:
General requirements, terms and definitions and tests

6.4.2 Quality of final rinse water

6.4.2.3 Tests for bacterial endotoxins
 If a requirement for the level of bacterial endotoxins in the final rinse water is given in
other parts of ISO 15883, determine the level by the limulus amoebocyte Iysate (LAL)
test with a sensitivity of 0,25 EU/ml, or better, using the method given in the European
Pharmacopeia (EP) or United States Pharmacopeia (USP).

6.4.2.4 Tests for microbial quality
 Make a total viable count by membrane filtration of not less than 100 ml final rinse
water sample. Place the filter on R2A-medium in accordance with Annex D, or other
suitable low nutrient medium and incubate at 28°C to 32 °C for a minimum of 5
days to determine the aerobic mesophillic viable count.
ISO 15883-1 Washer-disinfectors —Part 1:
General requirements, terms and definitions and tests

6.4.3 Quality of water used during testing

Prior to carrying out operational qualification and performance
qualification testing, determine the quality of water used at each stage
of the operating cycle other than the final rinse (see also 6.4.2).

Tests for chemical purity shall include tests for those determinants
known to influence the efficacy of the process.

NOTE This can include, but is not limited to, tests to determine the
value of the following:
 ⎯ conductivity;
 ⎯ pH;
 ⎯ oxidizable substances [determined by the European Pharmacopoeia (EP) method or
as redox potential determined
 by the United States Pharmacopoeia (USP) method];
 ⎯ total hardness (salts of Ca2+, Mg2+, Sr2+ expressed as mmol CaCO3);
 ⎯ total dissolved solids (TDS) determined as evaporative residue.
ISO 15883-1 Washer-disinfectors —Part 1:
General requirements, terms and definitions and tests

ISO 15883 -1 provides a qualification for the water quality but it does
not quantify limits

ISO 15883-1 does not provide a prescriptive specification for water

To a very large extent ISO 15883-1 remains subjective and subject to
interpretation and justification.

IF you are operating to ISO 15883 standard who ultimately determines
the standard for water quality?
ISO 15883-1 Washer-disinfectors —Part 1:
General requirements, terms and definitions and tests

5.23 Water supply

5.23.1 The quality of water required for each process stage shall
be specified by the WD manufacturer.
 When necessary, means shall be provided to monitor the attainment of this water
quality either periodically or continually for each cycle.
 NOTE The quality of water can include consideration of chemical purity, hardness,
temperature, supply pressure, microbial contamination, etc.
 The monitoring function can be provided by equipment external to the WD, installed
on the water supply system.

5.23.2 The WD shall be designed to operate either:
 a) with potable water supplied directly to the WD, or
 b) with potable water supplied to the water treatment equipment supplying the WD.
 Water treatment equipment can include, e.g. a softener, de-ionizer or reverse osmosis
plant, as necessary.
Guideline Compiled by the DGKH, DGSV and AKI
DGKH = German Society for Hospital Hygiene
DGSV = German Society for Sterile Supply
AKI = Working Group Instrument Preparation

The use of salt-free or fully demineralised water for the final rinse step
assures clean, spotless goods. Chapter 6.4.2.2 of EN ISO 15883 – Part
1 lists the critical parameters. EN 285, Annex B, Table B1, lists values
for the boiler water of a steam steriliser. This water quality can be
recommended for the final rinse step for automated instrument
processing.

The following values are recommended as a guide:







Conductivity: 5 μS/cm
pH value: 5 – 7
Total hardness: 0,02 mmol CaO/l
Salt content: 10 mg/l
Phosphate: (as P2O5) 0,5 mg/l
Silicate: (as SiO2) 1 mg/l
Chloride: 2 mg/l
Guideline Compiled by the DGKH, DGSV and AKI
DGKH = German Society for Hospital Hygiene
DGSV = German Society for Sterile Supply
AKI = Working Group Instrument Preparation

It is recommended that at the time of validation of the cleaning and
disinfection process the water quality used for precleaning, cleaning
and intermediate steps be documented too.

The following values are recommended as minimum requirements:




Total hardness: < 3°dH (< 0,5 mmol CaO/l)
Total salt: < 500 mg / l
Chloride content: < 100 mg / l
pH value: 5 – 8
Working group on Instrument Reprocessing AKI “Red Book”

Recommendations for thermal rinse water quality published in AKI “red
book” are based on EN 285 and ISO 17665 feed water quality for boilers

“Since there is currently no specific standard regarding the use of
demineralized water in automated reprocessing, we recommend the boiler
feed water quality as defined in DIN EN 285”.
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First Revision of AS 4187 picked up on EN285 and AKI
recommendation
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Choice Framework for local Policy and
Procedures (CFPP) 01-01
Management and decontamination of
surgical instruments (medical devices) used in acute care
Part D: Washer-disinfectors

Part 3 deals with all aspects of water supply.

Captures and updates the information on water quality previously
contained in the NHS Health Technical Memorandum (HTM) 2030
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Choice FrameworkPart D Washer
Disinfectors
Latest revision of AS 4187 (DR 100397 April 2014) references the UK
Dept of Health “Choice Framework”
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Is water quality testing compulsory?
Latest revision of AS 4187 (DR 100397 April 2014)

NOWHERE in the draft does it say water quality used for cleaning and rinsing
medical devices SHALL COMPLY with the water quality guidelines contained in
table 7.2.

The word SHALL in reference to water quality is used in the following context
7.2.3.1 Water quality ….“Softened, filtered, demineralized, reverse osmosis or
distilled water shall be provided in accordance with the requirements specified
by the equipment manufacturer”

In this regard DR 100397 is consistent with the ISO Guideline. IT IS
INCUMBENT UPON THE EQUIPEMNT MANUFACTURER TO SPECIFY THE
REQUISITE WATER QUALTY FOR YOUR FACILITY.

Just so there is no confusion as to which “equipment manufacturer” it means the
manufacturer of the washer.

Water quality falls under “Services qualification” which forms part of the
Installation Qualification (IQ). The IQ specification are the responsibility of
washer manufacturer.
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Is water quality testing compulsory?
Latest revision of AS 4187 (DR 100397 April 2014)

NOWHERE in the draft does it say water quality used for cleaning and rinsing
medical devices SHALL COMPLY with the water quality guidelines contained in
table 7.2.

Compare with the unambiguous direction for steam quality……”The quality of
water used for generation of steam for a sterilizing process SHALL comply with
the requirements in table 7.3”
Frequency of testing the water quality
Latest revision of AS 4187 (DR 100397 April 2014).
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Compare Frequency of testing in DR 100397 with
Choice Framework- Part D Washer Disinfectors

Existing AS 4187(2003) test hardness (weekly).

DR 100397 test water quality annually?
 Contains no other clear directions on frequency of testing ??

Choice Framework Part D
 Water hardness (weekly)
 Conductivity Final rinse (weekly)
 Chemical Purity tests (yearly)
 Bacterial endotoxins (yearly)
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Choice Framework – The key elements

The key factors are:

Hardness;

Temperature;

Ionic contaminants (for example heavy metals, halides, phosphates and
silicates);

Microbial population;

Bacterial Endotoxins
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Choice Framework – Microbial Quality and Bacterial Endotoxin

Bacterial Endotoxins

Items intended for surgically invasive use should have suitably low levels of
bacterial endotoxins.

Bacterial endotoxins are thermostable compounds primarily derived from the cell
wall of Gram-negative bacteria. When introduced into the human body, can
cause a fever-like (pyrogenic) reactions and other adverse effects. They are not
readily inactivated at the temperatures used for disinfection or sterilization.

Water used for the final stages of processing in a washer-disinfector, where
there is a significant risk of residual water remaining on the load items,
should not contain more than 0.25 EU/ mL–1 when the washer-disinfector is
being used to process surgically invasive items.
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Choice Framework – Treatment processes to remove Microbial
Contaminants and Bacterial Endotoxin

Bacterial Endotoxins

RO treatment plants remove almost all dissolved inorganic contaminants by
passing the water, under pressure, through a semi-permeable membrane
against an osmotic gradient. The process will also remove a high proportion
of organic material, bacterial endotoxins and microorganisms. Some RO
units are fitted with a final 0.2 μm filter to control bacterial numbers.

An RO system removes bacteria, endotoxins and approximately 95% of
chemical contaminants.

Water softeners, “base-exchange” softeners, de-ionisers do not remove nonionic contaminants such as organic materials, microbial contaminants, bacterial
endotoxins. Moreover ion exchange columns can become fouled and colonised
with microbial contaminant and cause a significant increase in the microbial
content of the water.

Deionised water should not be used for the final rinse of products intended for
invasive use without further decontamination processing by heating,f iltration
etc.
Choice Framework – Testing for Microbial Contaminants and
Bacterial Endotoxin

Bacterial Endotoxins

The sampling containers used should be specific for the determinands of
interest. This should include, as appropriate:

250 mL sterile pyrogen-free single-use containers (for determination of bacterial
endotoxin levels and/or total viable count);

Samples should be stored at 2–5°C and tested within 4 h (previously 48 Hours)
of collection.

HTM 2030 section 9.76. Samples should be tested within four hours of
collection or stored at 2ºC to 5ºC and tested within 48 hours of collection.
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Choice Framework – Ionic contaminants and
associated metrics

Hardness
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
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final rinse (both Choice and 4187 revision) <50mg/L .
4187 Revision other stages < 60mg/L
Choice other stages > 125mg/L should employ softening
Choice other stages >210mg/L not suitable for use
EN285 2mmol/L = 2ppm
Choice Framework – Salts & mineral contaminants and associated
metrics

Chloride
 <10mg/L in final rinse and <120mg/L other stages
 (chromomorphic salt - #1 suspect for pitting and crevice corrosion)

Heavy Metals (determined as lead)
 Final Rinse <10mg/L
 Causes staining and corrosion of steels

Iron
 Final Rinse < 2mg/L
 Causes corrosion of steels and staining

Phosphate
 Final Rinse < 0.2mg/L
 Contributes to scaling an blackening of steels

Silicate & Silica (SiO2)
 Final Rinse < 0.2mg/L
 Other stages <2mg/L
Choice Framework – Treatment processes to remove mineral
and ionic contaminants

Mineral contaminants will exist predominantly as dissolved ions.

Ions responsible for water hardness Ca, Mg together with other metals ions
responsible for staining can be removed by ion exchange systems such as
water softeners; water deionisers and RO treatment plants.

Ion exchange systems to not remove non-ionic species such as dissolved Silica
Dioxide.

Silica Slip

If ion exchangers are used in the production of fully demineralized water, glazelike discolorations may occur as a result of silicon dioxide passage. Quality
monitoring of the fully demineralized water by way of monitoring of electrical
conductivity is not adequate for identification, as the silicon dioxide does not
imbue the water with conductivity. Practical experience has shown that silicon
dioxide passage may occur even at electrical conductivity of approximately 1
μS/cm.
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Silica
Typical silica discoloration in the rinsing chamber and on the surface of the
instrument caused by cleaning agent containing silicate, or excessive levels of
silica in the water.
Choice Framework – Ionic contaminants and associated metrics
Conductivity & Total Dissolved solids

Conductivity
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Choice framework <30µs/cm
Choice framework tested weekly (Final Rinse)
revised draft DR100397 <30µs/cm
EN285 and AKI Redbook <5µs/cm (boiler feedwater)
The most telling parameter, captures the most information
It readily identifies changes in water quality and alerts you to when more
detailed analysis is required.
Total dissolved solids (TDS)
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


Choice framework 4mg/100mL = 40mg/1000ml = 40ppm (mg/L)
revised draft DR100397 <0.4mg/L???
TDS is measured as conductivity with a conversion factor applied.
TDS mg/L = electrical conductivity mS m–1 × 1.6.
Conductivity Toowoomba Hospital
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A Checklist of what a water quality standard should include

A water quality standard should provide a specification .

A clear unambiguous statement that Water used for final rinse and/or
cleaning SHALL comply with the requisite specification. Not left to other 3rd
parties.
Water quality specification
checklist
Current revision of AS4187 adapted
form “CHOICE FRAMEWORK”
Qualifies what to test for
YES
Quantitative limits
YES
Suitable methodologies
NO (contained in Choice Framework)
Testing frequency
NO (annual??)
Binding – SHALL COMPLY with spec.
NO (Not prescriptive. Defers to WD
manufacturer)
Water Quality Standards for CSD
A look at Australian, UK, ISO/EN, AAMI and
WFHSS standards and guidelines
QLD SRACA August 2014.