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6.5 Water Quality

WATER HARDNESS
Water with high mineral content is unsuitable for reprocessing flexible endoscopes and accessory items. It may reduce the efficacy of biocides and leave mineral deposits on equipment.

Water hardness is determined by the amount of calcium and magnesium ions present in the water. Water quality can be easily tested with test kits available from commercial manufacturers. Many health care facilities undertake a facility wide water treatment process.

For more information about your water quality contact the local water authority and also refer to the discussion of water quality in section two of AS4187.


WATER CONTAMINATION
It is increasingly recognised that hospital tap water may be contaminated with a variety of microorganisms. Pseudomonas and related species, atypical mycobacteria and Legionella are the most important frequently detected contaminants.

Factors effecting water contamination
Whether or not the hospital water is contaminated will depend on a wide variety of factors which include:
  • the quality of the water delivered to the hospital
  • the age and particular structure of the hospital plumbing system
    • if the plumbing is old or has been altered, particularly if there are blind endings and where there is not a frequent high flow of water, the risk of contamination is increased
  • the hot water temperature
    • systems which have the temperature regulated to prevent patient scalding will also increase the likelihood of water contamination
    • a constant temperature of at least 55°C at the point of use is necessary in order to prevent persistence of organisms in warm water


Risks associated with contaminated water
The principal risks of such contaminated water in endoscopy units are that:
  • endoscopes and accessory equipment will become contaminated during the washing or rinsing process
  • the organisms will proliferate in damp areas of the endoscope during storage
    • it is likely that this is one of the principal mechanisms for colonisation of endoscopes and disinfecting machines.
  • these organisms may be introduced to the next patient on the list


This risk of clinical infection is likely to be extremely small and probably only significant where an invasive procedure, e.g. injection sclerotherapy or ERCP is undertaken or if the patient has a severely compromised immune system, (e.g. leukaemia, HIV infection).

Contamination of biopsy or culture specimens may also cause confusion by falsely suggesting that infection is present, (e.g. pseudo infection). This risk has prompted a call for filtration of all water used to wash and rinse endoscopes. Such a general usage is both difficult, expensive and may carry its own significant problems. Filters which are not changed and/or regenerated (for example by steam under pressure sterilisation) may in fact become a source of contamination themselves, increasing rather than reducing the problem. In general, however, persisting vegetative pathogens are unlikely to survive in a completely dry environment.

Bacteriological examination of tap water is not simple. The tap mouth should be flamed to eliminate surface gram negatives and at least a litre (preferably more) of tap water needs to be collected. Therefore, a practical alternative to monitoring water quality or filtering water is meticulous air drying of all channels following an alcohol flush after each case.


GENCA and GESA recommendations

  • The quality of water delivered to the endoscopy unit be tested on a regular basis. Collection and testing methods should be determined in consultation with a microbiologist. If significant contamination is found then filters should be installed.
  • Where filters are installed they should be subjected to regular hygiene and maintenance processes according to the manufacturers protocol.
  • Filters for final rinse water in AFERs should be changed and/or regenerated regularly according to the manufacturer's instructions.
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