Compliance Resource · 2024 Update
AAMI ST108 Water Purification for Sterile Processing.
The complete 2024 compliance guide for hospital sterile-processing water systems. Category 1, 2, and 3 water limits, Joint Commission survey findings, and how to source ST108-compliant central RO, DI tank exchange, and preventative maintenance across Texas, Louisiana, Alabama, and Mississippi.
Water Categories Defined by AAMI ST108:2023
ST108 defines three categories of processing water. Each has explicit hardness, conductivity, TOC, and endotoxin limits.
| Category | Typical Use | Max Hardness | Max Conductivity | Max Endotoxin |
|---|---|---|---|---|
| Category 1Utility Water | Pre-cleaning, decontamination, first stages of instrument cleaning | ≤ 150 mg/L (CaCO₃) | ≤ 500 µS/cm | Not specified |
| Category 2Critical Water | Final rinse for reusable medical devices, terminal rinse for endoscope reprocessing | ≤ 1 mg/L | ≤ 10 µS/cm | ≤ 10 EU/mL |
| Category 3Sterile Water for Injection | Critical rinse where residual water can enter a sterile compartment | Trace | ≤ 1.3 µS/cm | ≤ 0.25 EU/mL |
Source: ANSI/AAMI ST108:2023, Water for the Processing of Medical Devices. Consult the full standard for complete specifications.
How Sterile Mate Helps You Comply
Six years serving hospitals across the Gulf region — Texas Medical Center to critical-access facilities in rural Mississippi.
Central RO & DI Systems
AAMI ST108–compliant central reverse-osmosis plus DI polishing loops for SPD, endoscopy, and pharmacy compounding.
DI Tank Exchange
Next-day medical-grade DI tank swaps — no contracts, cGMP + ISO 9001 regen facility.
Preventative Maintenance
Scheduled RO membrane cleaning, quarterly TOC/conductivity/endotoxin testing, and full survey-ready documentation.
Frequently Asked Questions
What is AAMI ST108?
AAMI ST108:2023 is the current U.S. consensus standard for water quality used in medical-device processing. It replaced the water sections of AAMI TIR34 and defines three categories of processing water (utility, critical, and sterile-for-injection) plus their required physical, chemical, and microbial limits. Compliance is expected by Joint Commission surveyors, DNV, and CMS.
How is AAMI ST108 different from TIR34?
AAMI TIR34 was a Technical Information Report (guidance). AAMI ST108 is a formal standard (mandatory language). ST108 replaces TIR34's water-quality content and adds explicit numeric limits, testing frequency, documentation, and staff-competency requirements. Facilities using TIR34 as their reference document should transition to ST108.
Do all hospitals have to comply with ST108?
Any facility that reprocesses reusable medical devices — hospitals, ambulatory surgery centers, outpatient clinics, dental practices with sterile-processing — is expected to meet ST108. Joint Commission, DNV, and CMS surveyors are actively citing ST108 non-conformance under EC.02.05.01 (utility systems) and IC.02.02.01 (medical equipment reprocessing).
What water categories does ST108 define?
Three categories: (1) Utility Water for pre-cleaning; (2) Critical Water for terminal rinse of reusable devices and endoscope reprocessing; (3) Sterile Water for Injection where residual water could contact a sterile compartment. Each has explicit hardness, conductivity, TOC, endotoxin, and bacterial limits.
How does Sterile Mate help hospitals meet ST108?
Sterile Mate provides ST108-compliant central RO systems, DI polishing tanks, DI tank exchange service, endotoxin/TOC/conductivity test kits, water-system preventative maintenance, and full compliance-audit documentation. We serve hospitals across Texas, Louisiana, Alabama, and Mississippi with same-day dispatch from Houston.
Joint Commission is actively citing ST108 non-conformance.
Since 2024, surveyors are writing findings under EC.02.05.01 and IC.02.02.01 for facilities that cannot demonstrate ST108-compliant water quality, testing frequency, or documentation. If you are unsure whether your facility meets ST108, request a compliance audit — we typically respond within one business day.