Water is one of the most essential, yet most overlooked components of medical device reprocessing. As expectations around patient safety, infection prevention, and regulatory compliance continue to rise, healthcare facilities are being asked to take a much closer look at how water quality impacts sterile processing outcomes.
Enter ANSI/AAMI ST108:2023, a new standard that fundamentally changes how water quality is managed, monitored, and documented in healthcare facilities.
While ST108 may not yet be formally “mandated,” it is quickly becoming the standard of care. Facilities that understand and adopt it early are positioning themselves for smoother operations, stronger survey outcomes, and better long-term reliability.
Why Water Quality Matters More Than Ever
Water touches nearly every step of medical device reprocessing, from flushing and cleaning to rinsing, disinfection, and sterilization. Even when instruments appear visually clean, improper water quality can leave behind chemical residue, microbial contamination, or endotoxins that compromise patient safety.
As device complexity increases and infection prevention expectations rise, water quality has become a critical variable, not a background utility.
Many of the challenges sterile processing departments face daily can be traced back to inconsistent or poor water quality, including:
- Instrument staining and spotting
- Residue after washing
- Premature corrosion and pitting
- Biofilm development
- Washer and sterilizer alarms
- Increased rework and workflow disruptions
When water quality is not properly controlled, the consequences extend far beyond the sterile processing department. Residual contamination left on instruments can pose serious patient safety risks, while ongoing exposure to poor-quality water accelerates instrument damage, leading to higher repair and replacement costs. These issues often result in operational downtime and surgical delays, disrupting schedules and increasing stress across clinical teams. At the same time, accrediting bodies are placing greater scrutiny on water management practices, meaning gaps in water quality programs can significantly increase survey risk.
From TIR34 to ST108: How We Got Here
What Was AAMI TIR34?
Before ST108, healthcare facilities relied on AAMI TIR34, a Technical Information Report that offered general guidance on water quality for reprocessing. While helpful, TIR34 was not a formal standard and lacked enforceable requirements. Interpretation varied widely from facility to facility.
Why Change Was Needed
Over the past decade, the industry has seen:
- Increased concern around biofilm and infection prevention
- More complex medical devices
- Inconsistent water quality practices across facilities
- Greater demand from surveyors for clear, enforceable expectations
Voluntary guidance was no longer enough.
Introducing ANSI/AAMI ST108:2023
ST108 represents a major shift. It is an ANSI-approved standard, giving it greater weight during accreditation surveys. Key updates include:
- Defined water categories: Utility, Critical, and Steam
- Measurable water quality parameters and limits
- Required routine testing and documentation
- Formal corrective action processes
- A required Water Quality Management Team
- System validation requirements (IQ, OQ, PQ)
The Big Difference
TIR34 = guidance vs. ST108 = standard
Key Requirements You Need to Know
1. Defined Water Categories
ST108 recognizes that not all water is used the same way:
- Utility Water: Used for cleaning and flushing
- Critical Water: Used for final rinses and residue-sensitive steps
- Steam: Now formally recognized as a contamination pathway
Each category has distinct quality requirements.
2. Measurable Water Quality Parameters
ST108 defines actionable limits for parameters such as:
- Hardness
- Conductivity
- Bacterial levels
- Endotoxins
Facilities are expected to test regularly, document results, and take action when limits are exceeded.
3. System Design Expectations
The standard addresses system design elements that directly affect performance, including:
- Flow velocity and recirculation
- Storage tank configuration
- Pretreatment and disinfection methods
Facilities must evaluate whether their systems truly support consistent water quality.
4. Monitoring, Trending, and Documentation
One of the biggest changes in ST108 is documentation. Surveyors now expect:
- Routine testing records
- Trend analysis
- Documented corrective actions
- Survey-ready logs
Annual or sporadic testing is no longer sufficient.
5. A Formal Water Quality Management Team
ST108 requires a collaborative approach. Sterile Processing, Facilities, Infection Prevention, and water treatment partners all share responsibility. Clear roles, communication, and accountability are now expected.
How to Get Started with ST108
- Assess: Conduct a gap analysis comparing current practices to ST108 requirements.
- Plan: Develop an implementation roadmap that includes budget, training, equipment, and documentation needs.
- Collaborate: Establish and engage your Water Quality Management Team.
- Implement: Roll out system improvements, monitoring, and SOP updates in a structured way.
- Validate: Document installation, operation, and performance qualification (IQ, OQ, PQ).
- Monitor & Improve: Ongoing testing, trending, and corrective action ensure long-term compliance.
ST108 represents a fundamental shift in how healthcare facilities manage water quality in sterile processing. While it may not yet be formally mandated, the direction is clear.
Facilities that take action now will be better prepared for surveys, experience fewer disruptions, and build stronger, more resilient reprocessing programs.
Understanding ST108 today means fewer surprises tomorrow.
