What Is Bacteriostatic Water?

Bacteriostatic water is sterile water with 0.9% benzyl alcohol added as a preservative. The benzyl alcohol inhibits bacterial growth, which is the entire reason it exists as a distinct product: a single vial can be punctured and drawn from more than once over about 28 days, instead of being discarded the moment it is opened like plain sterile water.

It searches enormously well and answers next to nothing on most of the pages that rank for it, because the people looking it up are usually trying to solve one of three problems: they do not know what it actually is, they assume a pharmacy stocks it and are confused when it does not, or they are trying to figure out where to actually get some. This page answers all three directly.

What it is used for

Its job is reconstitution: turning a freeze-dried (lyophilized) compound back into a liquid solution. Anything supplied as a powder in a sealed vial that needs to be dissolved before use, and drawn from more than once, is a candidate. In research settings this is most commonly a peptide. If you already have a peptide vial in front of you and need the exact dosing math, the full reconstitution guide covers volumes, concentrations, and step-by-step handling.

Can you buy it at CVS or Walgreens?

This is the single most searched question about the product, and the honest answer disappoints most people who ask it: no, not off a shelf. It is not merchandised as a walk-in retail item. A pharmacy counter can sometimes special-order it, but availability depends entirely on the individual store, it is rarely same-day, and plenty of pharmacy staff will not immediately recognize the product by name. Treat “my local pharmacy” as a slow, unreliable channel rather than a real option if you need it this week.

Is it “over the counter”?

Not in the pharmacy sense. The bacteriostatic water for injection that pharmacies dispense (Hospira, Fresenius Kabi) is labeled “Rx only”, so the counter will normally ask for a prescription. It is not a controlled substance. Research-grade vials sold for laboratory use move through medical supply distributors and online sellers, which is where almost every buyer ends up.

Bacteriostatic water vs. sterile water

Sterile water for injection has no preservative in it at all. The moment the seal is broken it is considered compromised for future use, so it is single-draw only. Bacteriostatic water's 0.9% benzyl alcohol content is the entire difference: it buys roughly 28 days of safe repeated use from the same vial after opening.

Storage, briefly

Unopened, it is shelf-stable at room temperature until the printed expiration date. No refrigeration is needed until the vial is punctured. Once it is opened, refrigerate it between 2 and 8 degrees Celsius and use it within 28 days. Where the 28 days come from, how to tell a vial has gone bad and what the fridge changes are in the shelf life and storage guide.

Where to actually buy it

Skip the pharmacy special-order route unless you genuinely have weeks to wait. We stock USP-grade bacteriostatic water in 10 mL glass vials with 0.9% benzyl alcohol, priced at $5 per vial, shipping from the US within 24 hours and arriving in 3 to 5 business days. Every batch is lab-tested for sterility, endotoxin level, and preservative concentration, with a COA available on request.

Frequently asked questions

This article is for laboratory and research use only. It is not medical advice, and nothing here should be taken as a recommendation to use any peptide or diluent on humans or animals. Always follow local regulations and consult a licensed healthcare professional for any medical question.