Bacteriostatic Water

What is bacteriostatic water?

Bacteriostatic water is sterile water containing 0.9% benzyl alcohol, a preservative that inhibits bacterial growth within the vial and so allows a sealed vial to be entered more than once during laboratory work. It is supplied as a laboratory reagent for research use only. For how it compares with plain sterile water and how it behaves once opened, see our explainer, what is bacteriostatic water.

What is bacteriostatic water used for?

In a research context, bacteriostatic water is used as a diluent to reconstitute lyophilised (freeze-dried) research peptides and other powdered laboratory materials, returning them to a workable solution. The 0.9% benzyl alcohol is what suits it to vials that may be entered more than once. Guidance on handling lyophilised research material is on our reconstitution page. This product is supplied strictly for laboratory research use and is not intended for human or veterinary use, and not for human consumption.

How is the quality and identity of this water assured?

Verify, do not assume. Each batch is supplied with documentation describing its composition, sterile water with 0.9% benzyl alcohol (benzyl alcohol, PubChem CID 244), so the contents are confirmed rather than taken on trust. Where a Certificate of Analysis applies it is available alongside our other documentation at our CoAs page. The standing principle across the catalogue is the same for a diluent as for a compound.

How should bacteriostatic water be stored?

Unopened vials are kept at room temperature, away from light and heat, until the labelled expiry. Once a vial has been opened, the benzyl alcohol is what allows it to be used for repeated laboratory entry rather than discarded after a single use. Keep vials sealed until needed and protect them from contamination during handling.

How long does bacteriostatic water last?

Unopened and correctly stored, bacteriostatic water lasts until its labelled expiry date. After a vial is opened it has a finite working life for laboratory use; no preservative inhibits growth indefinitely, so an opened vial is set aside once its appearance changes or it is no longer fit for laboratory work. This is reagent housekeeping rather than a use instruction.

Supply and reconstitution

Bacteriostatic water is despatched from the UK as a research diluent. It is the companion reagent to lyophilised research peptides such as BPC-157. For background on what this diluent is and how it differs from plain sterile water, see our explainer, what is bacteriostatic water.