A tray comes out of the washer with a chalky film. Instruments develop discoloration that keeps returning after cleaning. A sterilizer needs another repair for a leaking valve or deteriorating connection.
Each problem demands attention. When they recur, water quality deserves a place in the investigation.
The water used throughout sterile processing can affect instrument surfaces, cleaning performance, and equipment reliability. Mineral deposits and corrosion can indicate a need to investigate processing water. Recognizing those signs early gives a facility an opportunity to investigate before damage becomes more extensive. NHS guidance on washer-disinfectors and water quality
Appearance alone, however, cannot identify the cause. Detergent selection, rinsing, instrument handling, equipment condition, and water chemistry all belong in the same investigation.
Water participates in nearly every stage of reprocessing. It carries cleaning agents, removes loosened soil, rinses chemical residues, and supplies steam generation. Those functions make water quality part of the cleaning process itself. CDC guidance emphasizes that effective cleaning must precede disinfection and sterilization because residual material can interfere with subsequent processing. CDC guidance on cleaning medical devices
Recognizing the Warning Signs
Recurring surface changes are useful clues. Documenting their appearance and location can help narrow the investigation:
| Observation | Possible contributors to investigate |
|---|---|
| White spots or chalky deposits | Mineral deposits, including calcium and magnesium; cleaning or rinsing conditions |
| Rust-colored staining or chamber discoloration | Iron contamination, corrosion products, or deterioration elsewhere in the system |
| Unusual surface films or discoloration | Interactions between instrument materials, water constituents, and processing chemistry |
| Pitting or visible surface deterioration | Chloride exposure, chemical compatibility, retained residues, or other corrosive conditions |
These associations provide starting points for investigation. They do not establish a diagnosis or determine whether an instrument is suitable for use. Deposits and corrosion can have several contributing causes, which is why inspection and testing should be considered together. NHS guidance on water quality and instrument processing
How Water Chemistry Contributes to Damage
Understanding the chemistry helps explain why these problems develop. Water hardness primarily reflects dissolved calcium and magnesium. Under conditions that promote precipitation, those minerals can form scale on surfaces and within water-handling equipment. The U.S. Geological Survey describes how hard water contributes to mineral buildup in plumbing and equipment. A hardness result therefore helps investigate one important class of deposits, although it cannot characterize every contaminant in the water. USGS explanation of water hardness
Chloride exposure presents a different concern. Chloride in processing water can contribute to pitting and corrosion of stainless steel. Finding pitting should prompt a review of the instrument's entire processing history. Follow the instructions for the specific device when evaluating damage and deciding whether it can return to service. NHS guidance on chloride and corrosion
Cleaning chemistry also affects the outcome. Water composition, detergent formulation, device materials, and rinsing performance interact. Changing detergents without understanding the water supply can leave the underlying problem unresolved. Review concentration, dosing performance, temperature, contact time, and material compatibility with the relevant manufacturers. CDC guidance on cleaning agents and manufacturer instructions
Connecting Water Quality to Equipment Reliability
The consequences can extend well beyond individual instruments. In a January 2026 article, AAMI described an investigation at Phoebe Putney Memorial Hospital involving repeated failures of sterile processing equipment and plumbing. Testing identified elevated silica and other water quality concerns. The team combined laboratory findings with photographs, repair histories, and downtime information to support investment in improved treatment.
At the time of the article, the planned reverse osmosis replacement remained in procurement. The case illustrates how testing can support a maintenance and investment decision; it does not establish completed savings or prove that a particular treatment system will solve every facility's problems. AAMI's account of the hospital's investigation
Matching Water Testing to the Processing Stage
A useful investigation connects the water result to its intended use. ANSI/AAMI ST108:2023 addresses water used in medical device processing, including utility water, critical water, and steam condensate. Different processing applications have different quality expectations. A facility should identify which category applies at each location and review the requirements alongside device, equipment, and cleaning-product instructions. ANSI/AAMI ST108:2023
The laboratory request should reflect that context. Describe the affected equipment, the observed problem, the water treatment system, and the sampling location. Depending on the application, an investigation may include hardness, pH, alkalinity, conductivity, relevant metals and ions, and separate assessments of microbial quality or endotoxin.
A conductivity reading offers useful information about dissolved ionic substances, but it cannot establish microbial or endotoxin quality. Similarly, a sample collected immediately after treatment cannot establish conditions throughout the storage and distribution system. ST108 addresses monitoring at both water generation and points of use. ANSI/AAMI ST108:2023
Steam deserves its own attention when the problem appears during or after sterilization. Feedwater, the steam distribution system, and maintenance conditions can influence what reaches the sterilizer. Steam condensate testing evaluates chemical purity; physical steam quality involves additional characteristics that require appropriate assessment. An investigation can include feedwater and condensate testing, assessment of physical steam quality, and review of steam distribution components such as piping and traps. NHS technical guidance on steam sterilization
Six Steps for Investigating Recurring Problems
For a department facing repeated spotting, scale, or corrosion, the following sequence can help organize the work:
- Document the pattern. Photograph affected instruments and equipment surfaces. Record when the issue first appeared, which devices or loads were involved, and where they were processed. Separate observations from assumptions: “white deposit after washer cycle” is more useful evidence than an unconfirmed diagnosis of “hard-water damage.”
- Establish the appropriate response for affected items. Use the device and equipment manufacturers' instructions, facility procedures, and qualified inspection to determine disposition. CDC recommends inspecting equipment and repairing or discarding items that cannot function or be reprocessed properly. Laboratory results inform the investigation; they do not independently authorize returning damaged instruments to use. CDC recommendations for inspecting and maintaining equipment
- Bring the relevant teams together. Sterile processing staff can describe the pattern at the instrument level. Facilities and healthcare technology management can review treatment equipment, piping, service records, and operational changes. Infection prevention, the laboratory, and equipment or treatment vendors contribute additional expertise. ST108 defines roles for a multidisciplinary water management team. ANSI/AAMI ST108:2023
- Build a timeline before choosing a remedy. Compare the first appearance of the problem with maintenance events, water interruptions, construction, detergent changes, and equipment adjustments. Consider whether the issue affects one washer, one instrument type, or several processing areas. This comparison can help focus the investigation without prematurely assigning a cause.
- Coordinate sampling with the laboratory. Agree on the questions the testing needs to answer and the locations that can help answer them. Obtain the correct containers and collection instructions for each analysis. Record the exact location, collection time, and relevant operating conditions so that the result can be interpreted and compared with later samples.
- Verify the corrective action. Document what changed, who completed the work, and how effectiveness will be assessed. Review follow-up results alongside recurrence of deposits, instrument condition, and equipment performance. ST108 distinguishes performance qualification from routine monitoring and describes using baseline trends and alert levels to recognize developing problems. ANSI/AAMI ST108:2023
Using the Findings to Guide Treatment and Maintenance
Treatment decisions should follow the findings. Softening, reverse osmosis, and deionization serve different purposes. Their selection should account for incoming water, required output quality, equipment compatibility, demand, maintenance, and distribution conditions. An installed treatment system also needs ongoing verification; its presence alone does not demonstrate acceptable water at every point of use. NHS guidance on water treatment for washer-disinfectors
For leadership discussions, pair technical findings with a clear record of operational impact. Useful measures include instrument repair and replacement costs, repeat processing, service calls, equipment downtime, and staff time spent investigating recurring problems. Track those measures before and after corrective work. This gives the facility a way to assess whether the response improved reliability and whether further investment is justified.
How SteriTrust™ Supports Your Investigation
D and D Laboratory's SteriTrust™ sterile processing water testing service supports facilities with chemical and microbial testing, customized sample collection kits, laboratory reports, and assistance with sampling and results. Testing can give your team the evidence needed to evaluate water quality concerns alongside equipment inspections and maintenance records.
If your department is experiencing recurring spotting, scale, or corrosion, contact D and D Laboratory to discuss the affected process and appropriate water testing.
