Bacteriostatic Water (BAC Water)
What It Is & Why It Matters for Research
Bacteriostatic Water (BAC Water) is one of the most important tools in peptide research. While peptides arrive as a white, lyophilized (freeze-dried) powder, they must be reconstituted into liquid form before use in experiments. BAC water provides a safe, sterile, and longer-lasting way to prepare peptides for research.
Bacteriostatic Water is sterile water for injection that contains a small amount of benzyl alcohol (0.9%). The benzyl alcohol prevents bacterial growth, allowing the water to be used multiple times from the same vial without contamination. This makes it different from plain sterile water, which must be discarded immediately after opening.
Extends shelf life
Peptides reconstituted with BAC water can often be kept refrigerated for 20–30 days without issue.
Multi-use vials
Allows researchers to withdraw small amounts repeatedly using sterile technique, without discarding the vial after first puncture.
Cost effective
Reduces waste compared to single-use sterile water ampules.
| Sterile Water | Bacteriostatic Water |
|---|---|
| Sterile, no preservatives | Sterile + 0.9% benzyl alcohol |
| Single-use only (discard after opening) | Multi-use (up to 28 days after first puncture) |
| Good for sensitive applications where preservatives are not wanted | Best choice for peptide reconstitution in research |
- Unopened BAC water vials: store at room temperature in a clean environment.
- After opening: refrigerate and use within 28 days.
- Always use sterile needles/syringes to withdraw fluid and avoid contaminating the vial.
Can I use sterile water instead of BAC water?
Yes, but it must be used all at once. BAC water is recommended when multiple reconstitutions or repeated withdrawals will be made from the same vial.
Why does BAC water have benzyl alcohol?
The 0.9% benzyl alcohol acts as a preservative to stop bacterial growth. This small amount is enough to keep the solution safe for repeated use.
Does BAC water change peptide activity?
No, BAC water is the standard solvent for research peptide reconstitution. It does not alter peptide structure when stored properly at cold temperatures.
For Laboratory Research Only
This guide is for informational purposes related to laboratory research protocols. Not for human or veterinary use. All procedures should be performed by qualified laboratory personnel in appropriate research settings.
