Sterile Water for Injection vs. Sterile Water for Irrigation: Aquabiliti’s Superior Bulk WFI Solution for Pharmaceutical Manufacturing
Author
Erik Smeltz, Process Engineer, Aquabiliti
July 28th, 2025
Abstract
In the pharmaceutical, biopharmaceutical, and medical device industries, the choice of water used in manufacturing processes is critical to ensuring product safety, efficacy, and compliance with regulatory standards. Two commonly used types of sterile water — Sterile Water for Injection (WFI) and Sterile Water for Irrigation — serve distinct purposes, with different regulatory requirements and packaging allowances. This white paper outlines the differences between these two types of water, their permitted container sizes, and how Aquabiliti’s WFI, tested to USP Sterile WFI specifications and packaged in bulk, provides a practical and compliant solution for further manufacturing, laboratory, or research use. We also address why customers manufacturing pharmaceutical products can confidently use Aquabiliti’s bulk WFI instead of relying on smaller, traditionally packaged sterile WFI containers.
Sterile Water for Injection (WFI) vs. Sterile Water for Irrigation
Sterile Water for Injection (WFI)
Sterile Water for Injection, as defined by the United States Pharmacopeia (USP <1231>), is water purified by distillation or a purification process equivalent or superior to distillation (e.g., reverse osmosis followed by ultrafiltration) and rendered sterile. It is intended for use as a solvent or diluent in the preparation of parenteral products, such as injectable drugs, or for other applications requiring the highest level of purity and sterility, such as biopharmaceutical processing and medical device manufacturing. WFI must meet stringent requirements for conductivity, total organic carbon (TOC), bacterial endotoxins, microbial contamination, and particulate matter.
Regulatory Standards
USP: Specifies that Sterile WFI must have a conductivity of ≤1.3 µS/cm at 25°C, TOC ≤500 ppb, bacterial endotoxins <0.25 EU/mL, and ≤3 and ≤25 particles/mL of particulate matter ≥25µm and ≥10 µm in size, respectively.
Sterility: Must pass USP <71> sterility tests, ensuring no viable microorganisms.
Intended Use: Primarily for parenteral drug preparation, reconstitution of drugs, or as a solvent in manufacturing processes where sterility and purity are critical.
Container Size Allowed
According to USP and FDA guidelines, Sterile WFI intended for direct therapeutic use (e.g., as a diluent for injectable drugs) is typically packaged in single-use containers of 1 liter or less. This restriction ensures that the water is used immediately after opening to minimize the risk of microbial contamination during handling. Containers larger than 1L are generally not permitted for direct therapeutic use due to the potential for contamination once opened, as larger volumes are more likely to be stored or reused, increasing risk.
Sterile Water for Irrigation
Sterile Water for Irrigation, as defined by USP <1231>, is sterile water intended for external use, such as wound irrigation, surgical washing, or moistening medical devices (e.g., during surgery). It is not intended for injection or internal administration due to less stringent purity requirements compared to WFI.
Regulatory Standards
USP: Does not have a particulate matter requirement, as it is not used for parenteral administration.
Sterility: Must still pass USP <71> sterility tests since it’s a sterile product.
Intended Use: Primarily for external applications, such as irrigation of body cavities, wounds, or tissues, and cleaning of surgical instruments.
Container Size Allowances
Sterile Water for Irrigation can be packaged in larger containers, typically up to 3 liters or more, as it is designed for applications requiring larger volumes, such as surgical procedures or device rinsing. The larger container sizes are acceptable because the water is not intended for parenteral use, and the risk of systemic harm from minor contamination is lower.
Aquabiliti’s Bulk WFI: A Compliant Solution for Manufacturing
Aquabiliti delivers the best of both Sterile Water for Injection and Sterile Water for Irrigation by providing bulk water, with container sizes up to 1100L, tested to USP Sterile WFI specifications. The only distinction is that Aquabiliti’s WFI is intended for further manufacturing, laboratory, or research applications, rather than direct therapeutic use. There are several reasons why this approach is not only compliant but appropriate in industry:
Regulatory Alignment: USP and FDA regulations allow WFI to be packaged in volumes greater than 1L when it is not intended for direct parenteral administration. By clearly labeling our WFI for further manufacturing, laboratory, or research use, Aquabiliti ensures compliance with these guidelines, avoiding the 1L restriction applied to therapeutic WFI.
Intended Use Clarification: Aquabiliti’s WFI is marketed exclusively for applications where the water is further processed. This eliminates the risk of misuse in direct therapeutic applications, ensuring patient safety and regulatory compliance.
Quality Assurance: Despite being packaged in bulk, Aquabiliti’s WFI is produced using state-of-the-art purification systems and tested to meet USP Sterile WFI specifications. This ensures that the water is of the highest quality, equivalent to Sterile WFI (≤1L), but marketed appropriately for its intended use.
Customer Needs: Pharmaceutical and biopharmaceutical manufacturers often require large volumes of WFI for batch production. Aquabiliti’s bulk WFI meets these volume demands while maintaining USP-grade quality, offering a practical and cost-effective solution compared to purchasing multiple 1L containers.
Traceability and Compliance: Aquabiliti’s production and packaging processes are fully validated, with comprehensive documentation to support Good Manufacturing Practices (GMP). This ensures that customers receive a product that meets regulatory expectations for use in manufacturing.
Benefits for Manufacturers
Manufacturers producing pharmaceuticals or biopharmaceuticals that require Sterile WFI do not need to rely on 1L bags marketed as Sterile WFI for direct therapeutic use. Instead, they can use Aquabiliti’s bulk WFI, tested to USP Sterile WFI specifications, to achieve the following advantages:
Efficiency in Large-Scale Production: Manufacturers no longer need to purchase and handle multiple 1L bags of Sterile WFI, which can be labor-intensive and increase the risk of contamination during transfer to mixing tanks. Aquabiliti’s bulk WFI, tested to USP Sterile WFI specifications, is supplied in larger volumes (up to 1100L) tailored to batch requirements, streamlining the manufacturing process.
Cost-Effectiveness: Buying bulk WFI reduces packaging and handling costs compared to purchasing numerous 1L bags. This is particularly beneficial for large-scale production of pharmaceuticals or biopharmaceuticals, where high volumes of water are required.
Regulatory Compliance for Further Manufacturing: Because Aquabiliti’s bulk WFI is used for further manufacturing and not for direct parenteral administration, it is not subject to the 1L container size restriction. Manufacturers can confidently use this water in their processes (e.g., as a solvent for drug formulation or a rinse in medical device production), knowing it meets USP Sterile WFI standards and is fit for purpose.
Process Optimization: Bulk WFI eliminates the need to open and combine multiple 1L bags, reducing labor, waste, and the risk of contamination during handling. This is particularly critical in cleanroom manufacturing, where maintaining sterility is paramount.
Scalability: Large-scale manufacturing requires significant volumes of water. Aquabiliti’s bulk WFI, available in customizable volumes and single-use delivery systems, meets these demands without compromising quality or compliance.
Customizable Single-Use Solutions: Aquabiliti also manufactures single-use tubing and bags for filling bulk products, offering customized solutions to optimize integration with customers’ manufacturing systems. This ensures seamless and sterile delivery of WFI, reducing contamination risks and enhancing process efficiency.
Versatility Across Applications: Whether for drug formulation, bioprocessing, or cleaning, Aquabiliti’s bulk WFI provides the purity and compliance needed for a wide range of manufacturing applications, all while meeting the needs of large-scale production.
Conclusion
Sterile Water for Injection and Sterile Water for Irrigation serve distinct roles in the pharmaceutical and medical fields, with WFI requiring higher purity and stricter container size limits (≤1L) for direct therapeutic use, while Irrigation Water is suitable for external applications in larger containers (up to 3L or more). Aquabiliti’s WFI tested to USP Sterile WFI specifications and packaged in bulk, offers a superior solution for pharmaceutical, biopharmaceutical, and medical device manufacturers. By marketing this WFI for further manufacturing, laboratory, or research use only, Aquabiliti ensures regulatory compliance while meeting the needs of large-scale production.
Manufacturers no longer need to rely on cumbersome 1L bags of Sterile WFI for their batch solutions. Instead, they can leverage Aquabiliti’s bulk WFI, which provides the same high-quality standards in larger, customizable volumes, supported by single-use tubing and bags for seamless integration. This approach enhances efficiency, reduces costs, and maintains the highest levels of purity and compliance, making Aquabiliti the preferred partner for water-based solutions in critical industries.
For more information on Aquabiliti’s Sterile WFI and Sterile Water for Irrigation and how it can support your manufacturing needs, please Contact Us today through our website or email our team at customercare@aquabiliti.com
