If you're putting together injection supplies for the first time, the two names sound interchangeable. They aren't — and choosing the wrong one usually means throwing product away.

Bacteriostatic water

Bacteriostatic Water for Injection, USP is sterile water containing 0.9% benzyl alcohol. That preservative inhibits bacterial growth inside the vial, which is what makes it a multi-dose product: you can draw from the same 30 mL vial repeatedly. Per the manufacturer's labeling, an opened vial should be discarded after 28 days.

Sterile water

Sterile Water for Injection, USP contains no preservative. It is a single-dose product: once the vial is opened, whatever you don't use immediately should be discarded. For anyone reconstituting small amounts over days or weeks, that means wasting most of every vial.

Which one do you actually need?

For most people reconstituting products at home, bacteriostatic water is the practical choice — one vial covers many preparations instead of one. Always follow the labeling of the specific product you are reconstituting; if its instructions call for a different diluent, use what the label specifies.

One caution about sourcing

Bacteriostatic water is where suppliers most often cut corners — relabeled generics and gray-market stock are common. Our Complete Peptide Starter Kit only ever includes sealed vials manufactured by Hospira, a Pfizer company — an FDA-approved product, never substituted.

This page is general product information, not medical advice. Our products are supplies only and are not intended to diagnose, treat, cure, or prevent any disease. Bacteriostatic water is not for use in neonates.