Using AAMI ST108 to investigate water, steam, equipment, materials, and the full processing pathway
Discovering the root cause of buildup on instruments requires more than seeing it. Staff may suspect water first, especially when residue, staining, or buildup appears after cleaning or sterilization.
“Finding the source of particulates on surgical instruments requires more than a visual inspection. Water may be suspected first, but a thorough investigation must also look at steam, equipment, filtration, detergents, packaging materials, maintenance, and the complete instrument processing workstream.” – Len Sparks, Chief Operations Officer, VERDA Water Quality Systems
The goal is not to find the fastest explanation. Instead, the team must follow the evidence across the entire processing pathway.
“Water touches nearly every stage of medical device processing, but it cannot be evaluated in isolation. When you’re finding debris on processed instruments, hospitals need a multidisciplinary team that considers water, steam, equipment, materials, maintenance, and workflow as parts of one interconnected quality system.”
— Jeffrey Paquet, CEO, VERDA Water Quality Systems
This is Part 2 of VERDA’s three-part series. Part 1 explains why visible particulate should be treated as a broader quality-system signal rather than an isolated tray defect.
Why water belongs in a surgical instrument particulate investigation
Water quality can affect both the cleaning process and the condition of the finished instrument.
For example, poor water quality may contribute to:
- incomplete cleaning
- mineral deposits
- hardness scale
- staining
- corrosion
- reduced detergent performance
- residue on instruments or packaging
- shortened equipment life
- steam-quality problems
- repeat processing
- rejected trays
A facilities-focused review of ANSI/AAMI ST108 notes that improper water quality can contribute to incomplete cleaning, rusting, staining, hardness deposits, equipment problems, rejected instrument sets, unplanned maintenance, and SPD shutdowns.
In addition, the article cites an economic analysis estimating that a 110-bed hospital performing about 5,000 procedures each year could face up to $1 million in first-year disruption costs if steam-quality problems forced the sterile processing operation offline.
These consequences show why hospitals should not treat water as background infrastructure.
In Sterile Processing, water is a process input.
However, water is only one part of the investigation. The team should evaluate it alongside equipment, chemicals, materials, maintenance records, and process conditions.
How AAMI ST108 supports source investigation
ANSI/AAMI ST108:2023, Water for the processing of medical devices, gives hospitals a risk-based framework for managing water and steam used during device processing.
The standard addresses three principal categories:
- Utility Water
- Critical Water
- steam
ST108 focuses on water-quality outcomes, risk analysis, qualification, monitoring, documentation, and remedial action. And that is a departure from a lot of traditional thinking which tells hospitals to just purchase reverse osmosis equipment or another treatment technology.
Therefore, when unexplained particulate, staining, or residue appears, an ST108-informed investigation may review:
- incoming water quality
- Critical Water generation
- storage and distribution conditions
- point-of-use water quality
- steam quality
- recent repairs or shutdowns
- utility interruptions
- filters, membranes, resins, piping, and valves
- temperature and conductivity trends
- hardness, chloride, silica, metals, and pH
- microbial results
- detergent concentration and compatibility
- washer and sterilizer performance
- maintenance history
- evidence of component wear or degradation
It turns out that all of these things matter and can influence SPD water quality. So, this approach helps the team determine whether water or steam contributed to the problem. Just as importantly, it prevents the team from blaming water without evidence.
Why multidisciplinary investigation matters
No single department sees the entire medical device processing system.
For that reason, ST108 emphasizes the value of a multidisciplinary water management team. Depending on the facility, the team may include representatives from:
- Sterile Processing
- Facilities or healthcare engineering
- Infection Prevention
- Perioperative Services
- Clinical or Biomedical Engineering
- executive leadership
- water treatment specialists
- equipment manufacturers
- outside laboratories or technical experts
Each group contributes a different part of the picture.
Facilities understands boilers, water treatment, piping, steam generation, storage, and building infrastructure.
Sterile Processing sees changes in instrument appearance, washer performance, residue patterns, recurring tray problems, and workflow disruptions.
Perioperative personnel evaluate the finished product at the point of care.
Infection Prevention considers potential clinical implications.
Biomedical and technical specialists assess equipment function, component condition, and maintenance needs.
As a result, the investigation becomes stronger when the team combines these observations rather than reviewing them in isolation.
Investigating the source of particulate on surgical instruments
A structured investigation should follow the complete path of the instrument.
1. Preserve and identify the material
First, the team should preserve affected instruments and samples in a way that limits additional contamination.
Next, laboratory analysis may help determine whether the material is:
- mineral
- metallic
- polymeric
- fibrous
- organic
- detergent-related
- corrosion-related
- packaging-related
- microbial
Color and appearance may provide useful clues. However, visual inspection alone rarely confirms the material’s composition or source.
2. Determine where the material entered the process
The team should then review every stage that could have introduced the particulate.
Potential sources include:
- incoming water
- Critical Water treatment
- steam
- storage tanks
- distribution piping
- filters or membranes
- washer components
- sterilizer components
- detergents and lubricants
- tray liners
- wraps and rigid containers
- facility maintenance activity
- environmental shedding
For example, particulate found only after one washer cycle may suggest a localized equipment issue. In contrast, particulate found across several devices and locations may point to a broader source.
Therefore, the team should investigate the full processing route rather than focusing only on the place where staff discovered the defect.
3. Compare patterns across the process
One tray provides limited information. However, several observations may reveal a useful pattern.
The team should compare:
- affected device types
- washer and sterilizer identification
- processing dates and shifts
- load composition
- point-of-use locations
- water and steam results
- maintenance activity
- treatment-system changes
- detergent or chemical changes
- packaging materials
- staff reports
These comparisons may help the team distinguish an isolated event from a recurring system condition.
They may also reveal whether the problem appears after a specific repair, component change, chemical adjustment, or shift in water quality.
Water-quality monitoring must lead to action
ST108 describes monitoring as a prospective process that confirms whether control strategies are working and identifies when review or remedial action may be needed.
That distinction matters.
Monitoring is more than the collection of laboratory reports, meter readings, or sensor data. A hospital may perform extensive testing and still have a weak program when:
- no one reviews results promptly
- ownership is unclear
- action thresholds have not been defined
- failed results do not trigger escalation
- departments interpret results differently
- corrective actions are not documented
- recurring failures are treated as isolated events
- no one confirms whether the intervention worked
In other words, testing creates data. A functioning quality program turns that data into decisions and risk reduction.
For example, a conductivity result outside the expected range should lead to more than a note in a log. The team should know who reviews it, what threshold triggers action, which departments receive the alert, and what follow-up testing is required.
Without that structure, monitoring may describe the problem without helping the hospital control it.
Avoiding common investigation mistakes
Hospitals can weaken an otherwise strong investigation by making several common mistakes.
Assuming one cause too early
A visible residue may appear mineral-like, but appearance alone does not prove that water caused it. Likewise, a recent equipment repair may draw attention, but timing alone does not confirm the source. Therefore, the team should test competing explanations and document the evidence for each conclusion.
Testing only at the point of generation
Water may meet specifications where the facility produces it and still change before reaching the washer, sink, ultrasonic unit, or sterilizer. For that reason, point-of-use testing may reveal issues that generation-site testing misses.
Ignoring maintenance and change history
A new filter, detergent, valve, membrane, tray liner, or replacement component may alter the process. Therefore, investigators should review recent changes alongside water data and equipment performance.
Treating each affected tray as an isolated event
Repeated tray rejection may look like a series of small incidents. However, trend analysis may show a recurring pattern tied to equipment, timing, location, or materials. A quality system should connect those events rather than allow them to remain separate.
From assumption to evidence
Finding the source of particulate on surgical instruments requires evidence, multidisciplinary review, and a structured investigation of the entire processing pathway.
AAMI ST108 helps hospitals evaluate water and steam as critical process inputs. However, it also supports a broader risk-based approach that considers equipment, materials, maintenance, monitoring, and point-of-use conditions.
The most effective investigation does not begin with blame.
It begins with a question:
Where did the particulate enter the process, and what evidence proves it?
Once the team answers that question, the hospital can move from suspicion to action.
Next in the series
In Part 3, we examine how AAMI ST90 helps hospitals turn technical findings into standard work, root-cause analysis, corrective action, and long-term process control.