What Is Bacteriostatic Water and How Is It Formulated? At its core, bacteriostatic water is a specially prepared, sterile aqueous solution designed to suppress the growth of bacteria over time. Unlike plain sterile water, which provides no ongoing protection once a container is opened, bacteriostatic water incorporates a carefully measured concentration of a bacteriostatic agent—almost always benzyl alcohol at 0.9% volume per volume. The base is highly purified Water for Injection (WFI), produced through distillation or reverse osmosis to meet strict pharmacopoeial standards for conductivity, total organic carbon and microbial limits. This combination yields a diluent that can be punctured multiple times with a sterile needle without immediately becoming a…