Bacteriostatic Water (BAC Water) is a sterile, non-pyrogenic solution of water containing 0.9% benzyl alcohol, which acts as a preservative to inhibit bacterial growth. It’s commonly used to dilute or dissolve peptides and other medications before injection. Because of the benzyl alcohol content, BAC water can be safely used multiple times from the same vial (within 28 days of opening), making it a convenient and hygienic choice for research or laboratory applications.