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Water quality – Washer disinfectors
The quality of the water used in all stages of cleaning is important for good results.
The water used in each stage must be compatible with:
* The material that the washer disinfector is made of
* The chemicals used in the process
* Process requirements for the various stages of the process
The main factors for good water quality are:
Hardness
High hardness will cause limescale deposits in the washer disinfector, lead-
ing to poor cleaning results.
Ionic contaminants
A high concentration of ionic contaminants may cause corrosion and pitting
on stainless steel. Heavy metals such as iron, manganese or copper cause
instruments to tarnish.
Microbial contaminants
The water used should not increase the biological load on the equipment
that is being treated against micro-organisms and their residual products
which may cause fever-like symptoms when they get into the human body.
Sanitary chemicals
High concentrations of and high exposure to sanitary chemicals may cause
corrosion and pitting on stainless steel.
Getinge Disinfection AB therefore recommends that water used in the pre-rinsing,
washing and final rinsing phases should be of drinkable quality in accordance with
the guidelines .
Detailed information about acceptable water quality can be found in “Guidelines for
Drinking Water Quality, 3rd Edition” published by WHO.
Getinge Disinfection AB also recommends following local standards. RO (reverse-
osmosis) water (or similarly treated water) is used for the final washing/disinfection
phase. A typical specification for RO water is:
pH
5.5 till 8
Conductivity
<30 µs.cm
-1
TDS
<40 mg/l
Maximum hardness
<50 mg/l
Chlorine
<10 mg/l
Heavy metals
<10 mg/l
Phosphates
<0.2 mg/l as P
2
O
5
Silicates
<0.2 mg/l som SiO
2
Endotoxins
<0.25 EU/ml
Total number of micro-organisms
<100 per 100 ml
Further advice should also be obtained from the manufacturers of chemical and
medical equipment.
Where local standards are stricter than Getinge Disinfection AB’s recommendations,
they should be followed. Note that it is the customer’s responsibility to supply the
washer disinfector with suitable water.
