Introduction
With the release of ANSI/AAMI ST108:2023, sterile processing leaders face a new level of responsibility for water quality in reprocessing surgical instruments. The standard outlines requirements (the “shalls”) and recommendations (the “shoulds”)—but interpreting how they work together is essential for building a compliant and sustainable water management program.
Too often, the industry reduces ST108 to its “shall” statements alone. In reality, compliance is not achieved by checking boxes—it is demonstrated by producing and maintaining water of appropriate quality for every stage of instrument reprocessing. This white paper clarifies the role of both “shall” and “should” statements and provides guidance for how Sterile Processing Departments (SPDs) can prioritize their efforts.
1. What “Shall” and “Should” Mean in ST108
Shall: Mandatory. A requirement that must be followed to meet the standard.
Should: Recommended practice. Not strictly enforceable, but often critical to consistently meeting the “shall” requirements.
Importantly, some “should” statements carry such weight that they functionally act as “shall.” Facilities that ignore them may still fail to achieve the intended compliance outcome.
2. Compliance Is More Than Just “Shall”
While “shall” statements define the minimum baseline, compliance requires more than meeting those few clauses.
Section 9.1 Example: There is no explicit “shall” requiring performance qualification testing over time. Instead, ST108 explains that facilities need to monitor and test during startup and then shift to routine monitoring once stable performance is demonstrated. This “should”-driven process is how compliance is proven in practice.
VERDA and other industry leaders apply this by front-loading testing frequency during system startup, then tapering to routine monitoring once the water system demonstrates consistent performance.
3. The Role of “Should” in Water System Design
The design and implementation of water systems rely heavily on “should” statements. While only a handful of “shall” clauses address design (e.g., recirculation loops and sampling ports), most system reliability practices are recommended under “should.”
Examples include:
Designing future systems with recirculation loops (critical for reducing stagnation and microbial growth).
Ensuring steam condensate is tested to Table 2 parameters. Though written as “should,” this is not optional in practice—steam must meet these quality levels to be ST108 compliant.
Considering seasonal changes in water sources and adjusting pretreatment methods accordingly.
These recommendations are vital because ST108’s core concern is not how a facility configures its system, but whether the water produced meets the defined quality specifications for each processing step.
4. Why “Should” Often Feels Like “Shall”
Some “should” statements are so fundamental that they likely would have been written as “shall” had the committee wanted to prescribe methods as tightly as outcomes. Facilities should treat these statements as de facto requirements.
Example: The standard says steam condensate should be tested to Table 2. If a facility were to ignore that recommendation, it could not reasonably claim ST108 compliance since the steam’s impact on sterilization is critical.
5. Prioritization Framework for SPDs
SPDs often face limited resources and need a clear path forward. A practical way to prioritize:
Tier 1: Baseline Compliance (Shall Statements)
Address every explicit requirement. These form the non-negotiable foundation of ST108 compliance.Tier 2: Critical Support Practices (Should Statements with Direct Compliance Impact)
Implement design and monitoring recommendations that directly ensure water quality meets specifications—such as recirculation design, condensate testing, and proactive seasonal adjustments.Tier 3: Continuous Improvement (Remaining Should Statements)
Adopt remaining recommendations that improve efficiency, extend equipment life, and strengthen resilience against failures.
6. Equipment-Based Examples
Concrete equipment-related examples make ST108 actionable for SPDs:
Shall: Install sampling ports on both supply and return sides of a recirculation loop.
Should: Design the system with recirculation loops to prevent stagnation.
Should: Test steam condensate against Table 2 parameters to confirm water quality at sterilization.
These examples show how design “shoulds” directly support achieving the outcome defined by “shalls.”
Conclusion
Compliance with ST108 requires more than checking off “shall” statements. The standard’s true intent is that hospitals consistently produce water of the quality required for safe medical device reprocessing.
Shall = The baseline.
Should = The roadmap.
SPDs that prioritize both will not only achieve compliance but also reduce corrective actions, extend instrument life, and protect patients.