How to Store Bacteriostatic Water: Fridge or Room Temperature?

The named 30 mL Hospira bacteriostatic-water vial should be stored at room temperature, specifically 20 to 25°C (68 to 77°F). Refrigeration is not required by the label, either before or after the rubber stopper has been punctured, and freezing falls outside the labelled storage range.

Once a needle first passes through the stopper, write the date on the vial. The CDC convention is to discard a punctured multidose vial within 28 days unless its manufacturer gives a different opened-vial period, with the printed expiration date remaining the final limit in every case.

The vial covered here

Bacteriostatic water is sold in more than one presentation, so the instructions need to be tied to a specific product record. The storage temperature in this article comes from the current U.S. Hospira label published through DailyMed for its 30 mL multidose vial.

That presentation contains 9 mg/mL, equivalent to 0.9%, benzyl alcohol as a preservative. Its label calls for storage at 20 to 25°C, describes the contents as a clear solution and says the vial should not be used unless the seal is intact.

The Canadian record supplies a separate piece of information. Health Canada's Drug Product Database lists Bacteriostatic Water for Injection USP, DIN 00038202, as a marketed Pfizer Canada ULC product supplied in multidose vials to 30 mL. The database page does not provide the detailed benzyl-alcohol concentration or storage wording used above, which is why those points are attributed to the Hospira record rather than blended into a single Canadian label description. View our Pfizer Bacteriostatic Water 30 mL product page for current Canadian price and stock.

First puncture starts the 28-day period

People often say a vial has been "opened" as soon as the plastic flip cap is removed. That cap protects access to the rubber stopper, though removing it does not place a needle through the stopper or begin the CDC's post-puncture period.

The calendar starts when a needle first punctures the rubber stopper. Writing that date directly on the vial gives you a reliable reference instead of relying on memory several weeks later.

For an unopened multidose vial stored as directed, the CDC points to the manufacturer's printed expiration date. After first needle puncture, its guidance calls for the vial to be dated and discarded within 28 days unless the manufacturer provides a different period for the opened vial. The resulting date can never run beyond the original expiration printed on the container.

The 28-day mark is a conservative cutoff for a vial that has been entered repeatedly. There is no claim that the liquid suddenly changes colour, loses its preservative or undergoes a visible chemical shift when the calendar reaches day 29. A clear appearance cannot confirm that contamination has not occurred, so appearance alone cannot replace the dated cutoff.

Refrigeration leaves that calendar unchanged. Placing a punctured vial in the fridge does not pause the elapsed time, create a new first-puncture date or extend the official period, and moving it into a freezer is outside the 20 to 25°C storage range on the Hospira label.

The benzyl alcohol in the vial helps limit bacterial growth, which is why this product can be supplied as a multidose presentation. The CDC notes that an antimicrobial preservative does not provide complete protection from bacterial contamination, so the presence of benzyl alcohol does not remove the need to date the vial and pay attention to its condition.

Replace the vial when its history is uncertain

A vial should be replaced when you cannot establish when its stopper was first punctured. The same approach is appropriate when its temperature history is unknown, especially if it may have been frozen or left in sustained heat outside the labelled range.

The Hospira label calls for a clear solution and an intact seal. Cloudiness, discolouration, visible particles, leakage, a loose closure or any doubt about the seal are reasons to set the vial aside rather than trying to judge it by how much water remains.

A vial can still look completely normal after its history has become uncertain. Since contamination is not always visible, a clear liquid cannot supply the missing puncture date or confirm that questionable storage caused no problem.

After BAC water is added to a peptide

Once BAC water is added to a peptide, the peptide's own storage guidance takes over. The 28-day convention discussed here belongs to the original multidose BAC-water vial and does not determine how long the mixed peptide will remain suitable.

Temperature, composition and the characteristics of the individual peptide can produce a different storage period after mixing. Our separate guide on how to store research peptides covers that stage without transferring the BAC-water vial's 28-day calendar to every mixed product.

Reviewed July 2026

Research-use notice: Precision Synthetics Canada products and documentation are provided strictly for lawful, non-clinical laboratory research purposes only. COAs and testing records are not medical documents, safety guarantees, sterility guarantees, therapeutic endorsements, dosing guidance, or approval for human or veterinary use.