Bacteriostatic Water

Bacteriostatic water (BAC water) is sterile water containing 0.9% benzyl alcohol as a preservative. The benzyl alcohol inhibits bacterial growth, making it safe to use the same vial multiple times over up to 28 days after opening. This is critical for peptide research because most peptide vials contain multiple doses. When BAC water is added to a lyophilized peptide, it reconstitutes the powder into a solution that can be accurately dosed. Without the bacteriostatic agent, each vial puncture risks introducing bacteria that could contaminate the solution. BAC water vs. sterile water vs. bacteriostatic sodium chloride: Use BAC water as the default for peptide reconstitution. Use sterile water only for single-use applications or when benzyl alcohol sensitivity is a concern. Use bacteriostatic sodium chloride (0.9% NaCl with benzyl alcohol) when isotonicity is required. For step-by-step reconstitution instructions, use our reconstitution calculator at /tools/reconstitution-calculator.