Before you enter

PepPro Supply sells laboratory research supplies. Products are not evaluated or approved for human or veterinary use, and are not intended for any clinical, therapeutic, or diagnostic purpose.

By entering, you confirm you are 18 years of age or older and are purchasing on behalf of a laboratory or research use case.

FOR LABORATORY RESEARCH USE ONLY — NOT FOR HUMAN OR VETERINARY USE
Compliance & Terms  |  Order Status
🇺🇸
Cart (0)
Lab notes

Sterile water vs. bacteriostatic water: what's the difference?

PepPro Supply Lab Notes · Research use only

Both are water for injection-grade, but they're prepared for different situations, and mixing them up is one of the more common ordering mistakes in laboratory prep work.

Sterile water

Sterile water contains no preservative. It's intended for single use only — once a vial's septum is punctured, the contents should be used and the remainder discarded, since there's nothing in the water inhibiting bacterial growth after that point.

Bacteriostatic water

Bacteriostatic water has a small amount of benzyl alcohol added (typically 0.9%), which inhibits bacterial growth across multiple draws from the same vial over time. This is what makes it suitable for multi-use vials in laboratory settings, with a typical 28-day discard window after first puncture (see our shelf life article for details).

Which one to use

If a vial will be drawn from once and the remainder discarded, sterile water is the simpler and often cheaper option. If a vial will be accessed multiple times over days or weeks, bacteriostatic water's preservative makes it the more appropriate choice — using sterile water in that scenario introduces contamination risk with every additional draw.

This article is for laboratory research reference only. Products discussed are for in vitro laboratory research use only and are not evaluated or approved for human or veterinary use.