Bacteriostatic water is sterile water that contains a small amount of benzyl alcohol (typically 0.9%), an additive that inhibits the growth of bacteria. That preservative is what allows a vial to be accessed more than once over a limited period, unlike plain sterile water.
In laboratory, clinical, and research settings, bacteriostatic water is commonly used to dilute or dissolve powdered compounds - including certain medications and peptides supplied in a freeze-dried (lyophilized) form - into a liquid form for study and handling.
Because it slows bacterial growth, a multi-use vial can be drawn from several times within its usable window, which is often more practical than a single-use diluent for research workflows.
This article is for general educational purposes only and is not medical, health, or professional advice.