Bacteriostatic Water for Research Reconstitution

Everything below is general reference information for laboratory and research use only. Peptegridy products are not for human consumption and nothing here is medical, dosing, or administration guidance.

What bacteriostatic water is

Bacteriostatic water (often shortened to “bac water”) is sterile water that contains a small amount of benzyl alcohol — typically 0.9% — as a bacteriostatic preservative. The preservative inhibits the growth of most common bacteria, which is why a single vial can be drawn from more than once over its usable life without immediately spoiling.

That is the key difference from plain sterile water or sterile water for injection, which contain no preservative and are intended for single use. For research workflows where a reconstituted sample is stored and sampled over days or weeks, the bacteriostatic version is the common choice.

Why it's used to reconstitute lyophilized peptides

Many research peptides ship as a lyophilized (freeze-dried) powder because they are far more stable dry than in solution. To work with the material, researchers reconstitute it — dissolving the powder back into a liquid — and bacteriostatic water is a common diluent because it keeps the working solution usable across multiple sampling sessions.

• Add the diluent slowly against the vial wall rather than directly onto the powder pellet.
• Let the powder dissolve on its own; swirl gently rather than shaking, which can stress the peptide.
• Do not use water that is cloudy, discolored, or past its labeled life.

Storage and shelf life

Unopened bacteriostatic water is stored at controlled room temperature. Once a vial is opened and sampled, the preservative slows but does not permanently prevent contamination, so opened vials have a limited usable window — commonly cited as around 28 days — and should be kept clean and capped between uses.

Reconstituted research solutions are generally kept refrigerated (2–8°C), protected from light, and never frozen unless a protocol specifically calls for it. See our storage reference below.

In short

Bacteriostatic water is preservative-containing sterile water used as a multi-use diluent for reconstituting lyophilized research material. It is a lab supply — not a therapeutic product — and should be handled with clean, aseptic technique.