Bacteriostatic water
Sterile water containing 0.9% benzyl alcohol as a bacteriostatic preservative — the standard peptide reconstitution vehicle.
For laboratory and research use only — not for human consumption.
Bacteriostatic water (BAC water) is sterile water containing 0.9% benzyl alcohol, which inhibits bacterial growth in multi-dose reconstituted peptide vials. It is the most commonly used vehicle in peptide research because it allows multiple withdrawals from a single reconstituted vial over a typical 28-day refrigerated period. It is not appropriate for neonatal applications or for peptides where benzyl alcohol interferes with downstream assays; sterile water for injection is the alternative. In the UK, BAC water is a Schedule 4 medicinal product and supply is regulated; sourcing for in-vitro research use is generally straightforward through laboratory suppliers.