Water Quality
Correct cleaning procedures extend
life expectancy of instruments and
equipment
Issue management paper
Water Quality
www.getinge.com
Focus on water quality to ensure effective cleaning,
disinfecting and sterilization of medical devices
In the healthcare environment, water is a central part of cleaning, disinfection and steam
sterilization processes. Conversely, it’s also the primary culprit in the deterioration and wear
of medical instruments and equipment. Water is substantially H20, but everything else found
in water can be considered a ‘pollutant’ and must be monitored and checked regularly.
Natural water contains many pollutants, such as salts, organic solutes, micro-organisms,
particles and gases. Common impurities in water include metal salts and oxides, such as
copper, iron, calcium and lead; and/or harmful bacteria, such as Vibrio. Some solutes are
acceptable and even desirable for taste enhancement and to provide needed electrolytes.
But even if water is natural, it is considered to be insufficiently clean for use in the
sterilization process. While drinking water or tap water is usually pure enough to drink, it is
rarely pure enough for cleaning, disinfecting and sterilizing medical devices or instruments.
The presence of metal ions in water may
cause discoloration, the so-called ‘rainbow
effect’ on the surface of an instrument.
Hard water is an example. Hard water can cause calcium and magnesium deposits in
washer-disinfectors and stains on instruments. These visible or invisible deposits can
protect spores during sterilization, may remain on chamber walls and can also clog machine
components.
Metal ions are another pollutant. The presence of metal ions in water may cause
discoloration, the so-called ‘rainbow effect’ on the surface of an instrument. They can also
cause ‘replating’ of other, less noble metal instruments. Excess sodium will result in foaming
during cleaning and disinfection.
PH factors are also important. Bicarbonate, carbonate, and hydroxide affect water
corrosiveness. Acid environments with a low pH tend to be more corrosive to instruments
than alkaline environments.
Silicate deposits on the instruments are
opaque at first, and turn a dark blue when the
layers grow thicker.
Silicates (minerals with silicon) are found in water that is taken from sandy locations.
Deposits on the instruments are opaque at first, and turn a dark blue when the layers grow
thicker. Silicates in the steam during sterilization typically cause ‘snakeskin’ patterns on the
surface of instruments.
Corrosive anions (sulfate, fluor, chloride, nitrate, phosphate) are the major cause of pit
corrosion. Chloride for instance may be present in rinse water and steam.
The passive layer of stainless steel contains chromium to at least 10% or more by weight
and gives the steel its unique stainless, corrosion-resistant properties. But an unstable
passive layer, with inclusions or a breakdown of the passive film, can cause stainless steel
to corrode in the form of localized attacks (pitting).
2
Silicates in the steam during sterilization
typically cause ‘snakeskin’ patterns on the
surface of instruments.
Understanding pollutants and the different water
purification processes
The dangers of water impurities range from the risk of patient infections to higher hospital
costs as a result of device and equipment deterioration. Water impurities can destroy the
surface of instruments, and/or damage the chamber walls and components in the machines
used for cleaning and disinfection (washer-disinfectors) and sterilization (steam sterilizers).
To minimize these threats, an understanding of water quality and the different water
purification methods (filtering, softening, distilling, deionizing and reverse osmosis) is
vitally important. Healthcare professionals must understand how to test and evaluate water
quality, in order to determine the correct treatment and water quality goals.
With a softener or ion exchanger, magnesium and calcium ions are removed, exchanged
with sodium ions.
Distillation is the removal of dirt by boiling. The boiling water evaporates and is collected in
a clean container. Ionian and volatile organic compounds and chlorinated solvents are left
behind.
Deionizing removes all salts from the water. A possible drawback for steam sterilizers
(for certain types of level measurement in steam generators) is that when all salt ions are
removed, the conductivity of the water disappears. Salt dissolved in water is divided into:
• Cations (+) e.g. Na+, Ca2+, Mg2+
• Anions (-) e.g. OH-, Cl-, SO4 2There are two different methods to deionize: chemical and electrical. With the first method,
water passes through the chemical ‘filters’ that absorb salts. With the electrical method,
cathode and anode absorb the salts. Cations are pulled toward the cathode and anions
toward the anode.
Reverse osmosis occurs when water is projected under high pressure through a
semipermeable membrane. This is an extremely thin membrane, just like the cell
membranes that are found in both plants and animals. This membrane allows only small
molecules to get through; it separates bacteria and removes up to 98% of the salts in water.
Osmosis strives to smooth out/equalize the content (e.g. salt content) on both sides of
the membrane. Osmosis takes place in many instances in nature, for example when a tree
draws fluid nutrition from the soil.
Requirements for water quality during the sterilization process also vary, depending on how
the water is used – i.e. for cleaning, disinfection, feeding water to the steam generators, or
condensate from steam.
For washer-disinfectors, the
quality regulations DIN EN ISO
15883-1 specify:
• The quality of water required for
each phase shall be indicated by the
manufacturer of the washer-disinfector.
There should, where appropriate, exist
equipment to monitor compliance
on how the requirements on water
quality are achieved, periodically or
continuously, for each cycle.
• The quality of water can provide
an assessment of chemical purity,
hardness, temperature, feed pressure,
microbial contamination, etc. (section
5.23.1)
• The manufacturer of the washerdisinfector should request information
about the quality of the water available
from the user. The manufacturer
shall provide advice to users about
the necessary water treatment. In
the absence of reliable information
from the user, the quality of the water
should be tested in accordance with
6.4. (section 5.23.3)
• The quality of the water used in the
end of the sterilization process (final
rinse) needs to be tested according to
the EN ISO 15883-4 sections (washerdisinfectors for flexible endoscopes),
<10 cfu (colony forming units)/100 ml
sample of the final rinse and free from
Legionella, Pseudomonas aeruginosa
and mycobacteria.
To achieve this, in each process builtin sensors must measure and log
electrical conductivity, and once a week
microbiological quality needs to be
tested, measuring according to national
guidelines.
3
Learning how to manage water quality
Understanding water quality, and how the elements in water can affect cleaning,
disinfection and sterilization processes and the longevity of equipment, is key for healthcare
professionals responsible for device decontamination and equipment management.
Getinge’s training programs, offered through the company’s ‘Getinge Academy’, have
been developed to help participants achieve these goals. Visit www.getinge.com for more
information about training or contact information for Getinge Academy, or call or e-mail your
local Getinge representative.
71%
of the earth’s surface
is covered by water.
2.5%
is fresh water.
The Getinge Academy: the knowledge is the value
Getinge’s infection control systems provide hospitals with a complete solution for
effective cleaning, disinfection and sterilization. They’re designed to meet the needs of
sterile processing departments, sterile processing in the O.R., endoscope reprocessing,
dental, wards, outpatient clinics, and more. The product line includes washers, flushers,
sterilizers, loading equipment, accessories and software solutions.
98.8%
of that water
is in ice and groundwater.
In addition to industry-leading disinfection and sterilization equipment and solutions,
Getinge offers a comprehensive selection of professional training courses through the
Getinge Academy, including application areas of infection and contamination control.
Beyond the broad selection of standard courses available at the training centers, Getinge
Academy offers on-site training as well as distance learning on the internet. Courses can
be customized based on attendees’ level of knowledge, special requests and schedules.
The training staff has extensive experience across the healthcare sectors.
Reference
1.Gleick, P.H., ed. (1993). Water in Crisis: A Guide to the World’s Freshwater Resources. Oxford University Press. p. 13, Table 2.1 “Water reserves
on the earth”.
Getinge is the world’s leading provider of complete, ergonomical, cost-efficient solutions for effective cleaning, disinfection and
sterilization in the healthcare and life science sectors.
Getinge Group is a leading global provider of products and systems that contribute to quality enhancement and cost efficiency within
healthcare and life sciences. We operate under the three brands of ArjoHuntleigh, Getinge and Maquet.
ArjoHuntleigh focuses on patient mobility and wound management solutions. Getinge provides solutions for infection control within
healthcare and contamination prevention within life sciences. Maquet specializes in solutions, therapies and products for surgical
interventions, interventional cardiology and intensive care.