ANSI/AAMI ST108 Standard: Central Sterile Water Systems

The Central Sterile Water Systems are designed to meet or exceed the proposed standards

What is ANSI/AAMI ST108:2023?

The ANSI/AAMI ST108 standard, also known as the “Water for the processing of medical devices” standard, is a comprehensive set of guidelines for the design, construction, and operation of Central Sterile Departments (CSDs). The standard outlines the minimum requirements for water quality and steam purity necessary to effectively process medical devices intended for use on a patient. This standard was developed by the Association for the Advancement of Medical Instrumentation (AAMI) and is recognized as the gold standard for CSD operations.

The ANSI/AAMI ST108 standard is important because it helps to ensure that medical devices are sterilized to the highest standards, minimizing the risk of patient infections. Contaminated medical devices can transmit a variety of pathogens, including bacteria, viruses, and fungi, which can lead to serious infections in patients. By adhering to the AAMI ST108 standard, healthcare facilities can help to prevent these infections and protect the safety of their patients.

AAMI ST108 will not allow for direct feed systems in central sterile processing any longer, and thank goodness! The loop velocity of 3-5 feet per second being recirculated continuously through a 0.2 final filter will ensure that the last water that touches surgical instruments is free of bacteria and endotoxins. This means less surgical site infections!!

The technical information report 34 (TIR34) converted to Standard ST108 and covers the selection and maintenance of effective water quality suitable for reprocessing medical devices in central sterile water facilities. It provides guidelines for selecting the water quality necessary for the reprocessing of categories of medical devices and addresses water treatment equipment, water distribution and storage, quality control procedures for monitoring water quality, strategies for bacterial control, and environmental and personnel considerations.

Water can be treated by a variety of methods that yield different levels of water quality. In general, as the chemical quality of water improves, its microbial content could increase unless the system is closely monitored 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 to prevent problems with microbial overgrowth cannot be overemphasized.

The AAMI ST108 Central Sterile Water Systems are designed to meet or exceed the proposed standards put forth. The improved process water used in Water Systems lowers infection, protects equipment and improves patient outcomes.

Central Sterile Water Systems for AAMI TIR34

What will ANSI/AAMI ST108 require?


The best practice design provides for larger flow RO with a smaller fresh storage for your Critical Water Delivery System.  The design is compliant with AAMI TIR34 and brass/copper/lead free with rust free powder coated aluminum frame. Our deluxe controller with conductivity and optional facilities management communications package make it the most advanced solution on the market.

  • RO as pretreatment for DI pays for itself quickly
  • Less water waste with 40-75% recovery
  • Dedicated 115 Volt 20 amp circuit required
  • Minimal system floor space requirements
  • Optional Integrated Pretreatment Injection allows for smaller footprint and less maintenance (Chlorine Destruct/Antiscalent)
  • Ease hose Connection setup in minutes
  • Stainless Steel GRUNDFOS multi-stage RO Pump with integrated SS re-circulation pump for up to 30 GPM@40 PSI for re-circulation at 3 FPS


ANSI/AAMI ST108 Clean Water Standards Prevents:

  • Device breakage do to corrosion of a surgical instrument
  • Toxic effects due to residual endotoxins in the central sterile water supply
  • Patient infection caused by micro-biologicals in rinse water
  • Ineffective detergent performance due to contaminants binding to detergent surfaces

Design Specifications for Central Sterile Water Systems for ANSI/AAMI ST108

Design Specifications for Central Sterile Water Systems
Compact Central Sterile Water System

Complete systems are designed to feed your reprocessing requirements.

Footprint for Central Sterile System

More on ST108

ANSI/AAMI ST108: The Guide to Water Quality for Processing of Medical Devices

Surgical site infections are a leading cause of hospital re-admissions, many times due to water quality. Most sterilizers, washers and disinfectors used in the cleaning of surgical instruments are considered medical devices and require treated water within standards set by AAMI and IFU’s of the various device manufacturers.

CDC Toolkit On Ashrae 188

The Centers for Disease Control and Prevention (CDC) has developed a toolkit to guide building owners and managers in establishing and implementing effective water management programs.

Read Our WaterFACTs

Patient health doesn’t solely rely on the outcome of a surgical procedure, but also upon the sterile water treatment, cleanliness of the operating room and instruments used. Water quality could be the single most important factor for proper sterilization of surgical instruments. Learn more in our article.
AAMI ST108 for sterilization provides a water quality standard for medical devices. Water quality is an important consideration in all stages of medical device reprocessing and the equipment used to do so. Adequate water quality is a team effort between both the personnel who reprocess medical devices and the personnel who establish and maintain the water treatment system.
AAMI ST108 is an American National Standard that provides guidance on the quality of water used in the processing of reusable medical devices. It was published in 2023 and supersedes the previous standard, AAMI TIR34.