What Is Bacteriostatic Water?
Bacteriostatic water is sterile water that contains a small amount of benzyl alcohol (commonly around 0.9%), which inhibits the growth of bacteria — that is what “bacteriostatic” means. It is a common laboratory diluent. This page is an informational overview of the reagent and does not provide preparation-for-use or human-use instructions. Knowing what the name means, what the reagent contains, and how it differs from plain sterile water gives you the background to read its product page with confidence. The sections below walk through its composition, its common laboratory role as a diluent, and the general handling references that apply to it as a research-use-only catalog reagent. Throughout, the focus stays on what the reagent is and how it is handled, never on any use on a person or animal.
What the name actually means
The name explains the product. “Bacteriostatic” describes something that inhibits, or holds back, the growth of bacteria — “bacterio” for bacteria and “static” for keeping them static, or unable to multiply. So bacteriostatic water is simply water that has been given the ability to slow bacterial growth. It does this through a small amount of an added preservative.
It is worth being precise about that wording: bacteriostatic means it limits growth, not that it actively kills everything present. That distinction is part of why the reagent is described the way it is, and it is a useful detail when comparing it to other water products that carry different labels.
Composition: what is actually in it
The defining feature of bacteriostatic water is the added preservative, most commonly benzyl alcohol at a concentration of roughly 0.9%. That preservative is what limits microbial growth and gives the product its name. Everything else is sterile water. The additive is, in fact, the single ingredient that separates bacteriostatic water from plain sterile water.
Plain sterile water, by contrast, contains no preservative at all. It is simply water that has been sterilized. Both are clear liquids, but the presence or absence of that small amount of preservative is the meaningful chemical difference, and it is what leads to the two products being handled and described differently.
Sterile water versus bacteriostatic water
Because the two are easy to confuse, it helps to compare them directly. Sterile water is preservative-free and is typically treated as single-use, since once a sealed container is opened there is nothing in it to limit microbial growth. Bacteriostatic water, with its preservative, is often referenced over a longer working period because the additive continues to inhibit bacterial growth in the container.
That practical difference — single-use versus a longer working window — is the main reason a research setting might reference one over the other. Neither description here is a protocol or an instruction for any application; it is simply how the two reagents differ in composition and general handling.
Common laboratory role
In research settings, bacteriostatic water is frequently used as a diluent — a liquid used to dilute another material. Its appeal in that role comes from the preservative: because bacterial growth is inhibited, a sealed container can often be referenced over a longer period than preservative-free water would allow. This is a general description of the reagent's role, not a protocol for preparing any product for any use.
For PeptidesCanada specifically, bacteriostatic water is offered as a catalog reagent — see the BAC Water 10ml product linked below. Like every other item, it is a research-use-only material, described by composition and handling rather than by any use on a person or animal.
Storage and handling references
Bacteriostatic water is generally stored sealed, at room temperature or refrigerated according to its label, kept clean, and protected from contamination. Because the value of the preservative lies in keeping the container's contents controlled, avoiding contamination is the central handling idea. The product label is always the first reference for any specific storage detail.
As with any research reagent, the sensible approach is to follow the label that came with the product and your own handling references rather than a generic rule. The storage-and-receiving-records guide linked below covers recordkeeping practices that apply to reagents like this one as well as to lyophilized materials.
How it fits into a research catalog
Within a research catalog, bacteriostatic water sits alongside the other materials as a clearly labelled, research-use-only reagent. It is described the same way everything else is: by what it is and how it is handled, not by any use on a person or animal. PeptidesCanada lists it as the BAC Water 10ml product, and like every catalog item it carries the research-use-only positioning.
Understanding the reagent in those terms — a sterile water with a preservative, used in research as a diluent, stored sealed and protected from contamination — is enough to read its product page and documentation with confidence. For the related handling of dry materials it is often referenced with, the lyophilized-storage guide linked below is a natural next read.
Frequently Asked Questions
What is bacteriostatic water?
It is sterile water containing a small amount of benzyl alcohol, a preservative that inhibits bacterial growth, commonly used as a laboratory diluent.
What does "bacteriostatic" mean?
It describes something that inhibits or holds back the growth of bacteria, rather than necessarily killing everything present.
How is it different from sterile water?
Sterile water has no preservative and is typically single-use. Bacteriostatic water adds a bacteriostatic agent (usually benzyl alcohol) that limits microbial growth, allowing a longer working window.
What is bacteriostatic water made of?
Sterile water plus a small amount of preservative, most commonly benzyl alcohol at roughly 0.9%.
How is bacteriostatic water stored?
It is generally kept sealed and stored at room temperature or refrigerated according to its label, kept clean and protected from contamination.
Related Reading
Research Use Notice
All products referenced on this website are intended strictly for laboratory and research use only. They are not for human or animal use, and nothing on this page is medical, dosing, or legal advice.