Bacteriostatic water
Reconstitution solvent · Also known as BAC water, sterile water with benzyl alcohol
What is Bacteriostatic water?
Sterile water containing 0.9% benzyl alcohol used to reconstitute lyophilized (freeze-dried) peptides. The benzyl alcohol acts as a preservative, allowing the solution to be used multiple times over several weeks.
Bacteriostatic water is the standard solvent for reconstituting research peptides. Unlike plain sterile water, it contains a small amount of benzyl alcohol (typically 0.9%) that inhibits bacterial growth after the vial is punctured. This makes it safe to draw from the same vial multiple times over 3-4 weeks when stored in the refrigerator.
Benefits & evidence
How it works
Benzyl alcohol disrupts bacterial cell membranes, preventing microorganisms from growing in the solution after the vial seal is punctured. This is critical for peptide reconstitution because most protocols call for drawing multiple doses from a single vial over days or weeks.
Plain sterile water lacks this preservative and can only be used once. Sodium chloride (saline) is occasionally used as an alternative but is less common for peptide reconstitution.
Dosing information
Typical dosing protocol
1-2 mL per vial
Varies by peptide concentration1-2 mL per vial
Varies by peptide concentrationThe amount of water you add determines the concentration. More water means a lower concentration and easier dosing measurements. Use our reconstitution calculator to determine the right amount.