Introduction
Bacteriostatic water — often referred to as BAC water — is a sterile solution used widely in laboratory settings for peptide reconstitution and dilution. Unlike plain sterile water, bacteriostatic water contains a preservative that helps prevent bacterial growth, making it ideal for preparing peptide solutions and maintaining their stability over time.
This is why all of our products include bacteriostatic water as standard, supporting consistent preparation across our research peptide range.
What is Bacteriostatic water ?
Bacteriostatic water is sterile water that contains 0.9% benzyl alcohol, a preservative that inhibits the growth of microorganisms. This allows researchers to repeatedly withdraw small amounts from the same vial without introducing contamination.
Unlike regular sterile water, which is intended for single-use and lacks preservatives, bacteriostatic water can remain sterile even after multiple punctures, making it an efficient and practical choice for peptide preparation.
Why Bacteriostatic Water Is Preferred for Peptides
Peptides are sensitive molecules that can degrade quickly if exposed to bacteria or contaminants. Using bacteriostatic water helps ensure:
- Reduced bacterial contamination — the benzyl alcohol preservative inhibits growth.
- Multi-use convenience — a single vial can be accessed multiple times over an extended period (often up to ~28 days) if stored correctly.
- Greater stability — peptide solutions prepared with bacteriostatic water are less prone to spoilage compared to those made with plain sterile water.
Because of these benefits, bacteriostatic water has become the standard solvent of choice in many peptide research settings.
Bacteriostatic vs Sterile Water: Key Differences
It’s common for peptide researchers to wonder whether bacteriostatic water is really necessary. The key difference lies in the preservative:
- Bacteriostatic Water contains benzyl alcohol to prevent bacterial growth and support repeated access.
- Sterile Water is free from microorganisms but offers no protection against bacterial growth once the vial is opened and typically must be used immediately.
For peptide reconstitution that requires multiple dosing points or extended storage of a prepared solution, bacteriostatic water is often the superior choice in terms of convenience and contamination control.
How to Choose Quality Bacteriostatic Water for Peptides
When selecting bacteriostatic water for peptide work, consider the following
- Preservative level — ensure it contains benzyl alcohol at an appropriate concentration.
- Sterility assurance — choose water that’s sterile and quality-controlled for lab use.
- Storage stability — look for products that maintain sterility over time under correct conditions.
High-quality bacteriostatic water helps maintain the integrity of peptide solutions and reduces the risk of contamination throughout the research process.
Conclusion
Bacteriostatic water plays a crucial role in peptide research by providing a stable, sterile medium for reconstituting and diluting peptides. Its preservative content and multi-use capability make it a preferred choice over plain sterile water for many researchers. Understanding the differences and proper handling of bacteriostatic water can help improve the consistency and reliability of peptide preparation workflows.