What is the difference between bacteriostatic water and sterile water?

Sterile water contains no preservative and is intended for single use — once opened, it cannot prevent bacterial growth. Bacteriostatic water contains 0.9% benzyl alcohol, which inhibits bacteria and allows multiple withdrawals from one vial over several weeks. For multi-use peptide reconstitution in research, bacteriostatic water is standard.

The difference is the preservative. Sterile Water for Injection contains no antimicrobial agent — it is intended for single, immediate use, because once the vial is punctured there is nothing to prevent bacterial growth. Bacteriostatic Water for Injection contains 0.9% benzyl alcohol, which inhibits bacterial proliferation and permits repeated withdrawals from the same vial over roughly 28 days under refrigeration. Because reconstituted research peptides are typically used across multiple sessions of a protocol, bacteriostatic water is the standard reconstitution vehicle in laboratory practice. A small number of peptides are sensitive to benzyl alcohol, in which case sterile water with immediate use is documented as the alternative.

Source: Eur J Pharm Biopharm (2015) · PubMed

Bacteriostatic Water — 30mL, USP Grade purity →

Summarised from peer-reviewed literature for research reference. For laboratory research use only.