Bacteriostatic Water (BAC Water)
Sterile water containing 0.9% benzyl alcohol as a bacteriostatic agent, used to reconstitute freeze-dried peptides and injectable compounds.
Bacteriostatic Water (BAC Water) is a sterile, non-pyrogenic aqueous solution intended for reconstituting and diluting peptides and injectable biological compounds for multi-use purposes. Its basic formula is pharmaceutical-grade sterile water for injection with benzyl alcohol added at a precisely set concentration of 0.9% (9 mg/mL). Benzyl alcohol acts as a preservative that inhibits the growth and multiplication of bacteria and other micro-organisms (a bacteriostatic agent), giving the vial biological stability and protection against accidental microbial contamination when multiple doses are drawn with sterile needles, typically for up to 28 days after opening when stored properly — unlike ordinary sterile water, which is intended for single use only.
The sterile, safe medium for reconstituting peptides and keeping them pure across multiple doses
If you use peptides in research and biological applications, choosing the right liquid to reconstitute the freeze-dried (lyophilised) powder is the most decisive step in protecting the compound from damage and bacterial contamination — and this is where bacteriostatic water stands out as an essential, indispensable standard.
Classification: Sterile solvents and reconstitution solutions, microbial preservatives, peptide-preparation essentials (Reconstitution Solutions / Bacteriostatic Diluents).
Structurally, the solution consists of ultra-pure sterile water for injection with a very precise amount of benzyl alcohol at a concentration of nine-tenths of one per cent (0.9%) — the standard level sufficient to inhibit bacteria without affecting the stability of delicate peptide bonds.
Picture a vial of freeze-dried peptide being reconstituted: as soon as the first needle goes in, a tiny amount of outside air enters, and if ordinary water is used, the warm aqueous environment becomes an ideal breeding ground for microbes, breaking down the peptide and losing its effectiveness.
How it works
The benzyl alcohol in bacteriostatic water penetrates the cell membranes of bacteria and micro-organisms and inhibits their division and multiplication, without changing the pH of the medium or damaging the amino-acid chains of dissolved peptides. This growth-inhibiting property allows a reconstituted peptide vial to be kept safely in the refrigerator and used for repeated doses over several weeks, ensuring the solution stays sterile, pure and free of bacterial colonies or toxic products of microbial breakdown.
In laboratory and medical settings, it is the standard, trusted choice for reconstituting most freeze-dried peptides, research proteins and growth hormones, ensuring the highest biological safety and accuracy in dose stability.
The success of any peptide protocol does not depend only on the purity of the powder — it begins with the purity and safety of the liquid that restores that powder's biological activity.
The trusted sterile medium for storing and reconstituting peptides accurately and safely. Bacteriostatic water, known as BAC water, is the essential solution used to dissolve and store freeze-dried peptide compounds so they can be used repeatedly without contamination. It belongs to the class of sterile solutions and biological research solvents. Its formula is ultra-pure sterile water with 0.9% standard benzyl alcohol, acting as a protective shield that inhibits the growth of any bacteria or micro-contaminants that might enter while repeated doses are drawn. This unique feature gives the solution a safe refrigerated shelf life of several weeks without the amino-acid chains losing their chemical stability or therapeutic properties. Researchers trust it as the gold standard for reconstituting peptide powders and growth hormones with great efficiency and the highest biological purity — because precise results always require a sterile, carefully controlled environment that protects every drop from damage.
