Sterile Water Manufacturing and QC Testing

July 29, 2026

Bacterial endotoxin testing (BET) is required for any parenteral drugs, medical devices, or injectable liquids or pharmaceuticals that come into contact with the bloodstream. Included in this requirement are sterile, pharmaceutical, and injectable waters, as well as water for the processing of medical devices. Sterile water product monographs in the United States Pharmacopeia (USP), including sterile water for injection, inhalation, irrigation, and bacteriostatic water for injection, all require both sterility testing with USP <71> Sterility Tests and bacterial endotoxin testing with USP <85> Bacterial Endotoxins Test. However, it is important to distinguish these products from other water monographs that do not require sterility assurance, such as non-sterile water for injection, pure steam, and water for hemodialysis, that are not classified as sterile and only require USP <85>.^1,²

Bacterial Endotoxin and Sterility Testing for USP Water Monographs

Water Monographs that Require Only USP <85> Bacterial Endotoxin Testing	Water Monographs that Require Only USP <71> Sterility Testing	Water Monographs that Require both USP <71> Sterility and USP <85> Bacterial Endotoxin Testing
Water for Injection	Sterile Purified Water	Sterile Water for Injection
Pure Steam		Sterile Water for Inhalation
Water for Hemodialysis		Sterile Water for Irrigation
		Bacteriostatic Water for Injection

For the water products that require USP <85>, these products must be tested with Limulus amebocyte lysate (LAL), or an equivalent synthetic alternative can be used, such as a recombinant Cascade Reagent (rCR) following USP <86> Bacterial Endotoxin Testing Using Recombinant Reagents. Currently, the USP is in the process of approving the addition of USP <86> to the bacterial endotoxin testing requirements of the seven applicable water product monographs, listed above. This addition would make testing with recombinant bacterial endotoxin testing reagents fully equivalent to traditional USP <85> bacterial endotoxin testing for these specific products.³

Most water product monographs that require USP <85> have strict endotoxin limits, with most being below 1 endotoxin unit (EU) per milliliter. Water for hemodialysis requires an endotoxin level less than 1 EU/mL, bacteriostatic water for injection and sterile water for inhalation require less than 0.5 EU/mL, and water for injection (WFI), pure steam, and sterile water for injection and irrigation all require less than 0.25 EU/mL.

Sterile water product monographs that require sterility testing under USP <71> include those products that may be used for injection, inhalation, or irrigation as well. With sterility assurance for these products, a 14-day incubation period is required, unless otherwise shown to be unsuitable for certain timelines.

However, not all water monographs require both bacterial endotoxin testing and sterility assurance. For waters for pharmaceutical and analytical purposes, such as non-sterile water for injection, pure steam, or water for hemodialysis, sterility assurance is not required. USP <1231> Water for Pharmaceutical Purposes outlines the microbial testing guidelines for these non-sterile waters. This chapter, instead of requiring redundant or unnecessary sterility testing, sets “Alert and Action Levels” for microbial monitoring for these waters and guides users to set in-house monitoring specifications as needed. Often, these waters, rather than being used for clinical purposes, are used for laboratory or analytical purposes and do not require the same stringent sterility specifications as those used in clinical settings.⁴

Bacterial Endotoxin Testing and Microbiological Monitoring for Water Used in the Processing of Medical Devices

The importance of sterile and pharmaceutical water manufacturing is not limited to product specific monographs in the USP. In 2023, the Association for the Advancement of Medical Instrumentation (AAMI) released ANSI/AAMI ST108:2023 Water for the Processing of Medical Devices, which provides requirements and guidelines on the testing and monitoring of water systems used for the processing and manufacturing of medical devices. The standard puts forth guidelines on maintaining these water systems, including the implementation of requirements for bacterial endotoxin testing.5

Three categories of water are defined in the standard: utility water used for washing devices, steam condensate used for sterilization, and critical water used for reprocessing, sterilization, and rising. For critical waters used in sterile processing, the standard sets endotoxin limits of 10 endotoxin units (EU) per milliliter of water, meaning these waters require testing with LAL or an equivalent synthetic BET reagent on a monthly basis at minimum. The previous guidance, AAMI TIR34 Water for the Reprocessing of Medical Devices, did not require bacterial endotoxin testing for these waters, but instead recommended best practices for water quality control and microbiological monitoring.

For these bacterial endotoxin testing requirements, FUJIFILM Biosciences offers a variety of BET reagents, including natural LAL kits for quantitative and gel clot testing, as well as fully synthetic rCR tests. With a variety of methodologies and sensitivities, reagents for bacterial endotoxin testing from FUJIFILM Biosciences offer ease of use and full compliance for your testing needs.

Discover more about how pyrogen and sterility testing solutions from FUJIFILM Biosciences can help transform your testing strategy and respond to the demanding needs of quality control guidelines.

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