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What is AAMI ST108 for Sterilization?

AAMI ST108 is a water quality standard for medical device sterilization for the purpose of reprocessing equipment for future use. Water quality is an important consideration in all stages of medical device reprocessing. Ensuring adequate water quality in device reprocessing requires collaboration between the personnel who reprocess medical devices and the personnel who establish and maintain the water treatment system. Because the needs of these two groups are distinct, this technical information report (TIR) contains:

  • Sections in the main text that provide guidance for personnel involved in medical device reprocessing on the selection of the recommended water quality for each stage of medical device reprocessing for each category of medical device; and
  • Annexes that provide technical information to water maintenance personnel (i.e., personnel who are involved in water treatment and distribution in the facility) to guide them in setting up and monitoring water treatment systems.


AAMI TIR34 ST108 Learn More

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Why is Water Quality So Important in Sterile Processing?

Microbial content in water can increase without properly closely monitoring to prevent microbial overgrowth. Gram-negative bacteria and nontuberculous mycobacteria can grow in any type of water, including tap, softened, deionized (DI), reverse osmosis (RO) treated, and distilled water. The rate of growth and the microbial levels attained are a function of the amount of organic contaminants in the water. The importance of monitoring water quality, per AAMI TIR34 ST108 for sterilization, to prevent problems with microbial overgrowth cannot be overemphasized.

What Does Reprocessing Of Medical Devices Include?

The AAMI ST108 for sterilization defines two levels of water quality suitable for medical device reprocessing, and it describes the water treatment processes that can be used to obtain the correct water quality. To provide optimal water for medical device reprocessing, reprocessing personnel, and water maintenance personnel should collaborate with administrative personnel to implement adequate procedures as outline in the Standard.

Water for the Reprocessing of Medical Devices

This standard addresses how to determine the water quality needs for reprocessing various categories of medical devices at various stages of reprocessing and how to assess, generate, monitor, and maintain water meeting those requirements.


This TIR covers the quality of the water used to clean, rinse, disinfect, and sterilize medical devices. It defines water types on the basis of hardness, pH, microorganism levels, endotoxin levels, and other characteristics. The following specific topics are covered:

  • Importance of water quality and effective water treatment
  • Categories of water quality for medical device reprocessing
  • Selection of water quality
  • Water treatment systems
  • Monitoring of water quality
  • Strategies for microorganism control
  • Personnel considerations
  • Continuous quality improvement
  • Troubleshooting water quality issues

This TIR also provides definitions of terms and a bibliography. The annexes contain technical details pertaining to water treatment and monitoring for the benefit of water maintenance personnel.

To Purchase the TIR/Standard, go here!