Water for Glassware Washing

Impact of Water

• Hardness ions
  Calcium and magnesium salts can decrease the effectiveness of most detergents by binding with detergent surfactants, preventing them from dispersing soils. These salts are less soluble in hot water than in cold water, and can generate scaling. Scale deposits inside hot water pipes, around spray nozzles and on heating elements restrict water flow and reduce heat exchange efficacy, leading to increased heating and maintenance cost. In addition, as the water used for the final rinse is allowed to dry, “water spots” will appear on the items being rinsed if those ions are not properly removed.
  
  
• Silica
  Silica may also deposit on the glassware or instruments washed, inside the washers and on the heating elements. It provokes discolorations of metallic items.
  
  
• Metals and particles
  Iron, copper and manganese, as well as particles, may form deposits and reduce heat transfer. They may also deposit on the items being rinsed, increasing the risk of discoloration or corrosion of stainless steel items.
  
  
• Chloride
  Excessive chloride ions can cause corrosion pitting of stainless steel items.
  
  
• pH
  Although pH is not stricto sensu a water contaminant, it can change due to the presence of different water contaminants. Water pH can interfere with the effectiveness of detergents (especially enzymatic detergents).
  
  
• Organics
  Organics may interfere with the effectiveness of detergents. In addition, if water with a high TOC level is used for rinsing, water residuals can lead to discolorations.
  
  
• Bacteria
  Levels of bacteria present in the rinse water should be minimized, as they may deposit onto the items being rinsed. Bacteria by-products, such as endotoxins, may also be deposited. This may be a concern for items being used for applications sensitive to these contaminants.

Conclusion
It is recommended to use purified water for washing glassware and instruments, and final rinses especially should be done with purified water. Water purified by reverse osmosis is generally recommended; in some cases, pure (Type 2) water or even ultrapure (Type 1) water may be required. Some specific types of washers, such as washer-disinfectors for flexible endoscopes, may require a specific water quality. It is important to follow washer manufacturer guidelines and recommendations concerning feed water quality. In addition, compliance to norms or standards may be required.

More information

• AAMI TIR34:2007: Water for the reprocessing of medical devices: http://marketplace.aami.org/eseries/scriptcontent/docs/Preview%20Files%5CTIR340710_preview.pdf
• ISO 15883-1:2006: Washer-disinfectors - Part 1: General requirements, terms and definitions and tests

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