Sourcing Guide
Bacteriostatic Water How Long Is It Good For
Once a BAC Water Depot vial is punctured, the solution should be refrigerated at 2–8 °C and used within 28 days. The 28‑day period is based on USP <51> bacteriostatic effectiveness testing for Category 1B products. After this time, the preservative effect of the 0.9 % benzyl alcohol may diminish, increasing the risk of microbial growth. Discard any remaining solution after the 28‑day window, even if it appears clear.
- ISO 9001:2015 US facility
- USP <71> sterility tested
- Per-lot Certificate of Analysis
- Same-day US shipping
Direct Answer
BAC Water Depot’s bacteriostatic water remains stable for 28 days after the vial is punctured, provided it is refrigerated at 2–8 °C. Unopened vials are stored at controlled room temperature 15–30 °C and carry a USP <71> sterility test per lot.
How does the benzyl alcohol concentration affect bacteriostatic water stability?
BAC Water Depot formulates its bacteriostatic water with 0.9 % ± 5 % benzyl alcohol, verified by HPLC‑UV on every lot. This concentration inhibits bacterial growth without compromising the integrity of most research reagents. The USP <51> bacteriostatic effectiveness test classifies the product as Category 1B, meaning it reliably suppresses microbial proliferation for the approved post‑puncture period. A common failure mode is dilution below 0.5 % benzyl alcohol, which can allow low‑level contamination to proliferate, especially if the vial is stored above 30 °C after opening.
The benzyl alcohol also acts as a preservative that can interfere with certain enzyme assays if not accounted for. Researchers should verify assay compatibility, as the 0.9 % alcohol may affect enzyme kinetics or fluorescence read-outs. When preparing solutions, avoid excessive vortexing that can introduce air bubbles, which may trap microbes and locally reduce preservative efficacy. If cloudiness or precipitate appears, discard the vial.
What are the recommended practices for handling punctured vials to avoid contamination?
The lot’s Certificate of Analysis confirms sterility (USP <71>) and absence of microbial DNA (validated PCR assay). Use a sterile syringe for each withdrawal; re-using the same needle can introduce skin flora that bypasses the benzyl alcohol barrier. A frequent failure is drawing the solution into a non-sterile container, which creates a pathway for environmental microbes and may cause visible turbidity before the 28-day discard date.
Document the date of first puncture on the vial label; this simple log prevents accidental use beyond the validated 28‑day refrigerated period. If the vial is left at room temperature for more than 2 hours after withdrawal, the benzyl alcohol’s bacteriostatic effect can diminish, especially if the ambient temperature exceeds 30 °C. In such cases, discard any remaining solution and open a fresh vial to maintain experimental reproducibility.
How do USP test results on the Certificate of Analysis confirm product quality?
Each lot of BAC Water Depot bacteriostatic water undergoes USP <71> sterility testing via 14‑day membrane filtration; the CoA reports “no growth,” confirming the absence of viable organisms. The same lot is evaluated for bacterial endotoxin using USP <85> LAL, with a limit of ≤ 0.25 EU/mL, ensuring low pyrogenic risk for sensitive assays. Subvisible particulate analysis follows USP <788>, and container integrity is verified per USP <1207>. These independent laboratory results are accessible through a QR code on the vial, linking directly to bacwaterdepot.com/coa/<lot-number>.
Additional CoA metrics include pH (USP <791>) within the specified range for aqueous solutions, and verification of the benzyl alcohol net content by HPLC‑UV. The microbial PCR assay, validated for detection of microbial DNA, consistently shows “no detectable microbial DNA,” reinforcing the sterility claim. Failure to meet any of these specifications would result in lot rejection, so researchers can rely on the published CoA to confirm that the product meets all USP criteria before use.
Key Storage and Stability Parameters for BAC Water Depot Bacteriostatic Water
| Parameter | Unopened Vial | After Puncture | Reference USP Chapter |
|---|---|---|---|
| Shelf Life (unopened) | Until expiration date on label | 28 days | USP <51> |
| Benzyl Alcohol Content | 0.90 % ± 5 % | 0.90 % ± 5 % | USP <791> |
| Endotoxin Limit | ≤ 0.25 EU/mL | ≤ 0.25 EU/mL | USP <85> |
Key Facts
- BAC Water Depot bacteriostatic water is packaged in 10 mL Type I borosilicate multi‑dose vials.
- Each lot is tested for sterility by USP <71> membrane filtration with no growth observed.
- Benzyl alcohol concentration is verified at 0.9 % ± 5 % by HPLC‑UV per lot.
- The product is manufactured in an ISO 9001:2015‑registered facility in the United States.
- Orders placed before 2:00 PM CT Monday‑Friday ship the same business day from Dallas, TX.
Frequently Asked Questions
How long can I keep bacteriostatic water after opening it?
Once a BAC Water Depot vial is punctured, the solution should be refrigerated at 2–8 °C and used within 28 days. The 28‑day period is based on USP <51> bacteriostatic effectiveness testing for Category 1B products. After this time, the preservative effect of the 0.9 % benzyl alcohol may diminish, increasing the risk of microbial growth. Discard any remaining solution after the 28‑day window, even if it appears clear.
Do I need to refrigerate unopened vials of bacteriostatic water?
No refrigeration is required for unopened BAC Water Depot vials. They should be stored at controlled room temperature 15–30 °C, away from direct sunlight. This storage condition maintains the integrity of the benzyl alcohol preservative and meets the specifications listed on the label and Certificate of Analysis. Refrigeration before opening is unnecessary and could cause condensation inside the vial.
What USP tests are performed on each lot of bacteriostatic water?
Each lot undergoes USP <71> sterility testing via 14‑day membrane filtration, USP <85> LAL testing for endotoxin (≤ 0.25 EU/mL), and USP <51> bacteriostatic effectiveness (Category 1B). Additional assays include pH measurement (USP <791>), subvisible particulate analysis (USP <788>), and container integrity testing (USP <1207>). All results are compiled in a per‑lot Certificate of Analysis that can be accessed through the QR code on the vial.
Can I use bacteriostatic water for cell culture media preparation?
Bacteriostatic water from BAC Water Depot is suitable for preparing research‑grade solutions, including cell culture media, as long as the media formulation tolerates 0.9 % benzyl alcohol. The USP <51> test confirms that the preservative effectively suppresses bacterial growth for 28 days after opening. Researchers should verify that the alcohol concentration does not affect cell viability or assay read‑outs, and always store the opened vial at 2–8 °C.
What is the price per vial when buying in bulk?
BAC Water Depot offers tiered pricing: 25–49 vials cost $7.49 each, 50–149 vials $6.99 each, 150–499 vials $6.74 each, and 500 + vials $6.49 each. The single‑vial price is $9.99. Bulk orders over $250 qualify for free standard shipping on up to 100 vials, and orders placed before 2:00 PM CT ship the same business day.
How can I verify the quality of a specific lot of bacteriostatic water?
Each BAC Water Depot vial includes a QR code that links to the lot’s Certificate of Analysis at bacwaterdepot.com/coa/<lot-number>. The CoA lists USP <71> sterility results, endotoxin limits, benzyl alcohol content, pH, and particulate data. Because an independent third‑party laboratory performs the testing, researchers can independently confirm that the lot meets all published specifications before use.
What are common reasons for bacteriostatic water to become unsuitable before the 28‑day limit?
Even within the 28‑day refrigerated window, bacteriostatic water can become compromised if it is left at room temperature for extended periods, exposed to direct sunlight, or if the vial is opened with a non‑sterile needle. Cloudiness, precipitate, or an unusual odor often indicates microbial contamination or chemical degradation. In such cases, discard the solution regardless of the remaining time on the label.
Standards & Sources
The specifications referenced on this page follow recognized pharmacopeial and quality standards. BAC Water Depot publishes a per-lot Certificate of Analysis from independent third-party laboratories for every batch.
- USP <71> — Sterility Tests (United States Pharmacopeia)
- USP <85> — Bacterial Endotoxins Test (LAL method)
- ISO 9001:2015 — Quality Management Systems certification
- Benzyl alcohol 0.9% w/v — the bacteriostatic preservative standard for multi-dose vials