Different types of water require different monograph tests; even though there are eight different types of water most fall into four categories: Bulk Water, Water for Injection (WFI), Sterile Water and Sterile Water for Injection (SWFI).  To quality for USP grade material, each type will have to pass the tests outlined in the table below.

USP Monograph Test Bulk Water WFI Water Sterile Water Sterile WFI
Total Organic Carbon USP <643> <500 ppb <500 ppb <8000 ppb <8000 ppb
Water Conductivity USP <645> <1.3 μS/cm <1.3 μS/cm <5 μS/cm <5 μS/cm
Microbial Testing USP <1231> 100 cfu/mL 10 cfu/100 mL N/A N/A
Sterility Test <71>  N/A  N/A 14 days of no microbial growth 14 days of no microbial growth
Bacterial Endotoxin Test USP <85>  N/A <0.25 USP EU/mL <0.25 USP EU/mL <0.25 USP EU/mL
Particular Matter in Injection USP <788>  N/A  N/A  N/A  <25/mL


To explain this chart better, let’s define some of the key attributes: Bulk Water actually referes to Purified Water, Water for Injection, and Water for Hemodialysis.  The only reason WFI has its own category is because of how different the results must be for USP <1231> as well as USP <85>.  Sterile Water refers to Sterile Water for Injection, Sterile Purified Water, Sterile Water for Irrigation and Sterile Water for Inhalation.  Similar to WFI, Sterile WFI water has a one extra test, USP <788>.

Water Conductivity USP <645> values are presented at Room Temperature (25 degrees celcius), since conductivity varies with temperature.