Research Guides
What Is Bacteriostatic Water — and Why You Need It
Almost every lyophilized research peptide arrives as a dry powder that has to be dissolved before it can be used. The standard solvent for this is bacteriostatic water — and understanding it is essential for any peptide research workflow.
What it is
Bacteriostatic water is sterile water that contains a small amount of benzyl alcohol (typically around 0.9%) as a bacteriostatic agent. “Bacteriostatic” means it inhibits the growth of bacteria — which is exactly what makes it suitable for a vial that will be accessed more than once.
How it differs from sterile water
| Sterile water | Bacteriostatic water | |
|---|---|---|
| Preservative | None | ~0.9% benzyl alcohol |
| Use | Single use | Multiple withdrawals |
| Best for | One-time preparation | Multi-dose research vials |
Because plain sterile water has no preservative, a vial would risk contamination as soon as it is opened and accessed repeatedly. Bacteriostatic water solves this, making it the practical choice for reconstituting peptides that are used over several sessions.
How to use it
- Let both the peptide vial and the bacteriostatic water reach room temperature.
- Draw the desired volume of bacteriostatic water (see our reconstitution calculator to plan concentration).
- Add the water slowly down the inside wall of the vial — never inject it forcefully directly onto the lyophilized powder.
- Let the powder dissolve on its own, or swirl gently. Do not shake vigorously.
- Store the reconstituted vial at 2–8 °C, protected from light.
How much do you need?
The amount of bacteriostatic water you add determines the final concentration. More water means a more dilute solution and a larger volume to draw per dose; less water means a more concentrated solution. Our reconstitution calculator does the math for you — enter the vial amount, the water volume and your target dose.
Because it is needed for almost every peptide, ApexPro stocks bacteriostatic water as a standalone product and includes it in our research stacks.
RESEARCH USE ONLY. This article is provided for educational and research-planning purposes only. ApexPro products are intended exclusively for laboratory research and collector use — not for human or veterinary use, and not as a food, supplement, cosmetic or medicine. Nothing here constitutes medical, legal or professional advice.