“Our municipal water report says we meet EPA standards, but we’re still seeing corrosion, spotting, and wet packs in sterile processing. What are we missing?”
Answer from the Experts:
If you’ve ever asked this question, you’re not alone. Many hospitals assume that because their city’s water meets EPA drinking standards, it must also meet the requirements of ANSI/AAMI ST108:2023 — but that’s a costly misconception.
EPA Safe ≠ ST108 Compliant
EPA standards are written to protect human health for drinking water — not delicate surgical instruments. For example, the EPA’s secondary standard for chloride allows up to 250 ppm, while AAMI ST108 limits chloride to less than 1 ppm for Critical Water used in final rinses. That’s a 250-fold difference.
Water that’s “safe to drink” may still corrode your sterilizer piping, interfere with detergents, or leave mineral residue on instruments.
Why Your Municipal Water Source Matters
Municipal systems are dynamic. Source water can change seasonally, after storms, or when a utility adjusts its corrosion control chemistry under the EPA’s Lead and Copper Rule. These pH and alkalinity shifts ripple downstream, often disrupting your pretreatment equipment.
If you’ve noticed new staining or residue after years of good performance, your source water might have changed — and your pretreatment system may no longer be optimized for it.
Chlorine vs. Chloramines: It’s Not Just Semantics
Many municipalities have moved from free chlorine to chloramines (a combination of chlorine and ammonia). While chloramines persist longer in distribution systems, they’re also harder to remove. Standard carbon filters may not be enough — you need catalytic carbon or longer contact time to neutralize them effectively.
If you’re using the wrong filtration media, your downstream RO membranes can suffer premature fouling — and your instruments will show it.
Inside the Facility: Pressure, Temperature, and Steam
Even with perfect incoming water, things can go wrong inside the walls.
Pressure fluctuations can cause inconsistent flow to washers and sterilizers.
Water temperature that’s too hot can slow vacuum pumps, while water that’s too cold can prevent detergents from activating properly.
Steam quality directly affects sterilization: wet steam can lead to wet packs; too dry, and sterilization efficacy drops.
AAMI ST108 offers detailed guidance for maintaining dynamic water pressure and temperature stability to prevent these issues.
How Supplemental Disinfection Can Backfire
Facilities trying to reduce Legionella risk sometimes install continuous disinfection systems like monochloramine or copper-silver ionization. While well-intentioned, these can spike chlorine or metal levels beyond what your dechlorination and softening systems can handle — inadvertently pushing your Utility Water out of compliance with ST108 and shortening the life of downstream equipment.
Practical Steps for SPD Leaders
AAMI ST108 doesn’t just set limits — it calls for ongoing monitoring and collaboration across departments. Here’s where to start:
Establish a baseline: Obtain your current municipal water report and identify the disinfectant type and source water.
Test incoming water: Compare to ST108 Table 2 parameters (pH, conductivity, hardness, chloride, etc.).
Size pretreatment for the worst-case scenario: Design your system for seasonal variability, not average conditions.
Monitor monthly: Track pH, conductivity, chlorine/chloramine, and hardness.
Communicate: If water quality changes, coordinate with Facilities and your utility provider immediately.
The Takeaway
Water quality management is no longer “someone else’s job.” Under AAMI ST108, sterile processing leaders share responsibility for understanding their incoming water, monitoring ongoing performance, and recognizing when visual or operational changes point to water-related issues.
EPA compliance ensures safe drinking water — but AAMI ST108 ensures safe surgical outcomes.
Call to Action
Want to see how other hospitals have successfully implemented these principles?
Watch the full Belimed + VERDA webinar “Enhancing Facility Water: Implementing AAMI ST108 in Practice” (Episode 5) to hear real case studies and proven solutions.
If you’re looking for help, contact us.