What Is Sterile Water for Injection (SWFI, USP)?
Sterile Water for Injection (SWFI) is USP-regulated, sterile-filtered, non-pyrogenic water with no preservative. It is supplied as a single-use injectable pharmaceutical excipient — once the vial is pierced, remaining content must be discarded per its regulatory category.
Side-by-Side Specification
| Criterion | Bacteriostatic Water (BW-10) | SWFI |
|---|---|---|
| Preservative | 0.9% Benzyl Alcohol | None |
| Use Pattern | Multi-dose (research only) | Strict single-use |
| Regulatory Category | Research supply (RUO) | USP injectable excipient |
| Sterility | USP <71> sterile | USP <71> sterile |
| Endotoxin Limit | Non-pyrogenic | Non-pyrogenic |
| Pack Configurations | 10 mL, 30 mL, bulk | 5 mL, 10 mL, 20 mL, larger |
When to Use Bacteriostatic Water
Use bacteriostatic water for any research reconstitution requiring multi-draw use over a 28-day in-use window. The preservative provides the bacteriostatic protection needed for prolonged in-use stability.
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When to Use SWFI
Use SWFI only when a single reconstitution event is needed and the remaining volume will be discarded. SWFI is also required when a clinical or veterinary protocol specifies a preservative-free vehicle — but note that BAC Water Depot products are for research use only.
Frequently Asked Questions
Is SWFI the same as bacteriostatic water?
No. SWFI contains no preservative and is strict single-use. Bacteriostatic water contains 0.9% benzyl alcohol and supports multi-dose use within a 28-day in-use window.
Can I use SWFI in place of bacteriostatic water for research?
For single-event reconstitutions where the remainder will be discarded, yes. For multi-draw protocols, no — the absence of preservative means SWFI cannot safely support repeated punctures.
Why is SWFI more strictly regulated?
SWFI is a USP-regulated pharmaceutical excipient produced for human/veterinary injection. Bacteriostatic water sold for research is regulated as a research supply (RUO) and is not for human or veterinary use.
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ISO 9001:2015 USA-manufactured. Three independent labs verify every production lot. CoA available per lot.
