The Two Major Types of Water Used in Sterile Processing


You may have heard the terms “Utility” water and “Critical” water. Whatever happened to “tap” water and “treated” water? Those terms were not specific enough to define how best to process instruments in a Sterile Processing department. Tap water is supposed to meet the EPA drinking water standards. Maybe it does, maybe it doesn’t. “Utility” water is what tap water is supposed to be, with specified ranges for a number of parameters. “Treated” water is a meaningless term. It can be tap water run through a sand filter to get the rocks out. It can be softened. It can be carbon filtered. It can be reverse osmosis/deionized (RODI). “Critical” water has specified maximum contaminant levels that establish a minimum purity level. So, what do you do with them? The applications are what matter and these are based upon recommendations and requirements in AAMI TIR34 “Water for Reprocessing of Medical Devices”, ST79 and other standards and best practices. Detergents are designed to dissolve and clean well in utility water, although you may have to tailor your dose to match the specific parameters you have. Rinsing with it works well, too. But “works well” isn’t good enough for medical devices for patient safety and instrument longevity. To finish the job, you need Critical water. Critical water has far lower contaminant levels, so it can dissolve residual mineral, detergent, and soil deposits that may remain on the instrument, finishing the job of making instruments clean, residue free and sterilizable. See you next month!