Testing Levels Needed to Meet ST108 Standard for Sterile Processing
When performing ST108 testing or ST108 risk assessments, below are the standard levels that need to be met for specific elements in the water. You can refer to these levels during your processing efforts for central sterile to set requirements and monitor progress. Also see our ST108 testing packages.
| Water Quality Measurement | Units | Utility Water | Critical Water | Steam* |
| pH @ 25 °C: | Units:pH | Utility Water:6.5 – 9.5 | Critical Water:5.0 – 7.5 | Steam*”5.0 – 9.2** |
| Total Alkalinity | Units:mg CaCO3/L | Utility Water:<400 | Critical Water:<8 | Steam*”<8 |
| Bacteria | Units:CFU/mL | Utility Water:<500*** | Critical Water:<10 | Steam*”N/A |
| Endotoxin | Units:EU/mL | Utility Water:N/A*** | Critical Water:<10 | Steam*”N/A |
| Total Organic Carbon (TOC) | Units:mg/L (ppm) | Utility Water:N/A | Critical Water:<1.0 | Steam*”N/A |
| Color and Turbidity | Units:Visual | Utility Water:Colorless, clear, without sediment | Critical Water:Colorless, clear, without sediment | Steam*”Colorless, clear, without sediment |
| Ionic Contaminants | ||||
| Aluminum | Units:mg/L | Utility Water:<0.1 | Critical Water:<0.1 | Steam*”<0.1 |
| Chloride | Units:mg/L | Utility Water:<250 | Critical Water:<1 | Steam*”<1 |
| Conductivity | Units:μS/cm | Utility Water:<500 | Critical Water:<10 | Steam*”<10 |
| Copper | Units:mg/L | Utility Water:<0.1 | Critical Water:<0.1 | Steam*”<0.1 |
| Iron | Units:mg/L | Utility Water:<0.1 | Critical Water:<0.1 | Steam*”<0.1 |
| Manganese | Units:mg/L | Utility Water:<0.1 | Critical Water:<0.1 | Steam*”<0.1 |
| Nitrate | Units:mg/L | Utility Water:<10 | Critical Water:<1 | Steam*”<1 |
| Phosphate | Units:mg/L | Utility Water:<5 | Critical Water:<1 | Steam*”<1 |
| Sulfate | Units:mg/L | Utility Water:<150 | Critical Water:<1 | Steam*”<1 |
| Silicate | Units:mg/L | Utility Water:<50 | Critical Water:<1 | Steam*”<1 |
| Total Hardness | Units:mg CaCO3/L | Utility Water:<150**** | Critical Water:<1 | Steam*”<1 |
| Zinc | Units:mg/L | Utility Water:<0.1 | Critical Water:<0.1 | Steam*”<0.1 |
* Steam parameters are for monitoring as steam condensate
** For local steam generation, the condensate pH should be 5.0 to 7.5. For boiler-treated steam, most boilers should be treated to maintain a condensate pH of 7.5 to 9.2
*** When Utility Water is used after chemical high-level disinfection as a final rinse, the bacteria should be <10 CFU/mL and endotoxin <10 EU/mL
**** If hardness is greater than 150 mg/L a water softener is recommended unless used for washing where the cleaning chemistry is capable of handling higher levels of hardness
Water quality management is crucial for every industry, including healthcare, hospitality, correctional facilities and manufacturing. Working with Legionella Control Systems gives you access to independent, expert insights and proven solutions for managing water safety. Contact Legionella Control Systems to schedule a site assessment today or call us for rapid testing.
