The Association for the Advancement of Medical Instrumentation (AAMI) introduced Standard ST108 in 2023 to replace the previous AAMI TIR34:2014/(R)2021 standard. AAMI ST108 includes guidelines on:
- Categories of water quality: Defines water quality requirements for each stage of sterile processing.
- Water quality monitoring: Sets criteria for assessing water quality, including turbidity, pH, microbial levels, conductivity, and other factors.
- Water treatment: Establishes protocols for maintenance, monitoring, and quality improvement in water treatment systems.
AAMI ST108 is considered a best practice for patient safety and is likely to become a requirement of other standards, like The Joint Commission Water Management Standard EC.02.05.02.
Categories of water quality
AAMI ST108 standardizes water quality for medical device processing to prevent adverse outcomes associated with substandard water. It defines three primary water quality levels—utility, critical, and steam—each tailored to different stages of device sterilization and disinfection.
- Utility water or tap water is generally minimally processed and used for tasks like flushing and washing.
- Critical water requires higher purity levels for tasks like high-level disinfection and final rinsing.
- Steam is used in sterilization and must meet specific standards to ensure safety and efficacy.
The standard includes extensive testing protocols to ensure water quality across these categories. Key testing criteria include turbidity, pH, microbial levels, conductivity, and various chemical parameters.
Water quality monitoring
To comply with ST108, facilities must routinely test utility, steam, and critical water to ensure consistent quality. Water testing should cover microbial and chemical parameters as well as general water quality metrics like turbidity, pH, and total organic carbon. Routine testing frequency is determined based on initial validations and risk assessments, with periodic testing following interruptions, repairs, water advisories, or in response to adverse outcomes (e.g., staining, discoloration, or deposits on medical equipment).
Facilities should create sample locations representative of water contact points and monitor this over time to ensure ongoing compliance with ST108 standards.
All water quality parameters, monitoring and verification protocols, and control measures should be incorporated into the facility’s existing water management plan.
Water treatment
In the ST108 sterilization process, water treatment is divided into three main stages: pretreatment, primary treatment, and storage/distribution/final treatment. Each stage is essential in preparing high-purity, sterile water for medical and sterilization equipment. Here’s a breakdown of how these stages are structured.
Stage 1: Pretreatment
The pretreatment stage prepares water for further purification. This step ensures that downstream equipment operates efficiently by removing larger particles, sediments, chlorine, and hardness, which could cause damage or interfere with subsequent treatments.
- Sediment filtration: Filters particles and sediment from the utility water that could harbor bacteria or clog and damage equipment.
- Carbon filtration: Dechlorinates water by removing chlorine and organic compounds.
- Water softening: Reduces hardness (calcium and magnesium) to prevent scaling and extend equipment life.
Stage 2: Primary treatment
The primary treatment stage refines water quality to meet strict purity and safety standards, making it suitable for medical sterilization applications. The goal of this stage is to achieve high levels of purity by removing dissolved ions, organic contaminants, and microorganisms.
- Reverse osmosis (RO): Uses a semipermeable membrane to filter out ions, organic matter, and some microorganisms, creating purified water.
- Deionization (DI): Uses ion-exchange resins to further purify the water by removing any remaining dissolved salts and ions.
Stage 3: Storage, distribution, and final treatment
This stage maintains water quality during storage and distribution and ensures the highest purity right before use. The purpose of this stage is to prevent microbial contamination and ensure that water remains sterile at the point of use.
- UV disinfection: Provides final microbial inactivation by using UV light to disrupt bacterial DNA.
- Point-of-use filtration: Use of micropore or ultrafine filters at the final outlet to prevent contaminants from entering the sterilization cycle.
Incorporating ST108 into your water management program
To incorporate ST108 into your water management plan, start by reviewing your current water treatment processes and identifying areas that need alignment with ST108’s requirements. Involve key personnel such as facility managers, infection preventionists, clinical engineering staff, medical device processing personnel, and water safety specialists who understand both operational needs and regulatory standards. These specialists will assess your existing setup, identify gaps, and update treatment protocols to ensure compliance.
Collaborate with water treatment experts to implement technologies that meet ST108 criteria at each stage of water handling, from pretreatment to storage and distribution. For example, they may recommend sediment filtration, softening, or UV disinfection systems tailored to your facility’s usage patterns and contaminant profile.
Additionally, integrate regular testing and monitoring into your water management plan to ensure ongoing compliance and make adjustments to processes as needed.
Partnering with LiquiTech to comply with ST108
LiquiTech simplifies ST108 compliance with targeted solutions that streamline water quality monitoring and control.
- Water quality testing facilitation
- Coordination services to streamline ST108 testing compliance.
- Automatic shipment of sampling bottles and coordination with third-party labs.
- Water management program integration
- Support in incorporating ST108 guidelines into your water management plan.
- LiquiTech® Sediment Filtration (pretreatment)
- Removes particulates from utility water to meet ST108 standards, making it suitable for critical applications.
- Protects reverse osmosis (RO) and deionization (DI) systems by reducing fouling and scaling, which extends equipment lifespan and lowers maintenance costs.
- Minimizes biofilm formation to reduce microbial risks.
Ready to get started? Contact LiquiTech today to see how we can help your facility comply with AAMI ST108.
