Sourcing Guide
Bacteriostatic Water How To Make
Bacteriostatic water is sterile water that contains 0.9 % benzyl alcohol, which inhibits bacterial growth without killing the organisms. The benzyl‑alcohol concentration is tightly controlled at ±5 % and verified by HPLC‑UV for each lot. This allows researchers to keep reconstituted solutions stable for up to 28 days after the vial is punctured, provided the solution is refrigerated. BAC Water Depot provides this formulation in 10 mL borosilicate vials that meet USP <71> sterility standards.
- ISO 9001:2015 US facility
- USP <71> sterility tested
- Per-lot Certificate of Analysis
- Same-day US shipping
Direct Answer
Bacteriostatic water is sold by BAC Water Depot as a research‑use‑only 0.9 % benzyl‑alcohol solution in 10 mL Type I borosilicate multi‑dose vials. Each vial costs $9.99 and is USP <71> sterility‑tested, with an expiration date printed on the label.
How is bacteriostatic water prepared in a laboratory setting?
The preparation of bacteriostatic water begins with pharmaceutical-grade water that meets USP <791> pH specifications (typically 6.5-8.0). Benzyl alcohol is present at a final concentration of 0.9 % (±5 %). The filtered solution is aseptically transferred into Type I borosilicate vials, which are sealed with tamper-evident closures. A common failure mode is incomplete filtration, which can be detected by a post-filtration microbial assay; any growth would require the batch to be discarded and the filter integrity re-tested before reuse.
After filling, each vial undergoes USP <71> sterility testing via 14‑day membrane filtration and USP <85> LAL testing for endotoxin (≤ 0.25 EU/mL). The lot is also examined for subvisible particulates per USP <788> and container integrity per USP <1207>. If the endotoxin assay exceeds the limit or particulate counts are high, the entire lot fails and must be re‑processed. Documentation of these tests is compiled into a Certificate of Analysis that is accessible via a QR code on the vial label.
What are the quality‑control specifications for bacteriostatic water used in research?
BAC Water Depot’s bacteriostatic water meets a full suite of USP specifications: sterility (USP <71>) shows no growth after 14 days, bacterial endotoxin (USP <85>) is ≤ 0.25 EU/mL, and bacteriostatic effectiveness (USP <51>) qualifies as Category 1B. The benzyl‑alcohol content is confirmed by HPLC‑UV at 0.90 % ± 5 %, and pH is measured within the USP <791> range. A frequent quality‑control issue is deviation in benzyl‑alcohol concentration, which can arise from inaccurate weighing; such a lot would be flagged during HPLC analysis and rejected before release.
Each lot is also screened by a validated PCR assay for microbial DNA, ensuring no detectable contaminant genetic material. Subvisible particles are counted under USP <788> criteria, and any vial exceeding the allowable count is excluded from the final release. The independent third‑party laboratory publishes the full test results on the lot’s Certificate of Analysis, and the QR code on each vial links directly to that document for transparent verification.
Can bacteriostatic water be compounded with other reagents for experimental protocols?
When compounding, the 0.9 % benzyl‑alcohol concentration must be preserved to maintain bacteriostatic activity; adding large volumes of acidic or basic solutions can shift the pH outside the USP <791> range and reduce effectiveness. Researchers should verify that the final pH remains between 6.5 and 8.0 using a calibrated pH meter. A typical failure mode is precipitation of salts when high‑ionic‑strength buffers are mixed without adjusting the pH, which can render the solution unsuitable for downstream assays.
Because the base product is USP <71> sterile, any breach in aseptic technique after opening the vial will invalidate sterility; therefore, the compounded mixture must be stored at 2–8 °C and discarded after 28 days, matching the post-puncture storage requirement of the original vial.
Storage and handling requirements for BAC Water Depot bacteriostatic water
| Condition | Temperature Range (°C) | Action | Maximum Duration |
|---|---|---|---|
| Unopened vial | 15–30 | Store at controlled room temperature, no refrigeration | Until expiration date |
| Punctured vial | 2–8 | Refrigerate | Discard after 28 days |
| During transport (US) | 15–30 | Room‑temperature shipping, no cold‑chain | Up to 7 days |
| After opening for compounding | 2–8 | Refrigerate | Discard after 28 days |
Key Facts
- BAC Water Depot manufactures bacteriostatic water in an ISO 9001:2015‑registered facility in the USA.
- Each lot is tested for sterility by USP <71> membrane filtration with no growth observed.
- Bacterial endotoxin levels are ≤ 0.25 EU/mL per USP <85> LAL assay.
- Benzyl alcohol content is 0.90 % ± 5 % verified by HPLC‑UV.
- Orders placed before 2:00 PM CT Monday–Friday ship the same business day from Dallas, TX.
Frequently Asked Questions
What is bacteriostatic water and why is benzyl alcohol added?
Bacteriostatic water is sterile water that contains 0.9 % benzyl alcohol, which inhibits bacterial growth without killing the organisms. The benzyl‑alcohol concentration is tightly controlled at ±5 % and verified by HPLC‑UV for each lot. This allows researchers to keep reconstituted solutions stable for up to 28 days after the vial is punctured, provided the solution is refrigerated. BAC Water Depot provides this formulation in 10 mL borosilicate vials that meet USP <71> sterility standards.
Can I use bacteriostatic water for cell culture media preparation?
Yes, but you must ensure that the final pH of the media remains within the USP <791> range (6.5-8.0) after adding the 0.9 % benzyl-alcohol solution. Excessive buffering or high-salt concentrations can cause precipitation, which is a common failure mode. Unopened vials are stored at controlled room temperature, 15–30 °C, out of direct sunlight. Store any leftover bacteriostatic water at 2–8 °C and discard it after 28 days, matching the post-puncture storage rule.
How is the sterility of each vial verified?
Each lot undergoes USP <71> sterility testing using a 14‑day membrane filtration method. The test looks for any microbial growth in both fluid and filter cultures. Results are documented on a per‑lot Certificate of Analysis that is accessible via a QR code on the vial label. BAC Water Depot also runs a validated PCR assay to confirm that no microbial DNA is present, providing an additional layer of assurance.
What are the endotoxin limits for this product?
Endotoxin is measured by the USP <85> Limulus Amebocyte Lysate (LAL) assay, and the specification for BAC Water Depot bacteriostatic water is ≤ 0.25 EU/mL. This limit is verified for every production lot by an independent third‑party laboratory, and the results are posted on the lot’s Certificate of Analysis. Maintaining endotoxin below this threshold is critical for experiments that are sensitive to pyrogenic effects.
Is there a difference between Type I borosilicate and regular glass vials?
Type I borosilicate glass has a low coefficient of thermal expansion and superior chemical resistance, reducing the risk of leaching or breakage during handling. BAC Water Depot uses 10 mL Type I borosilicate multi‑dose vials, which meet USP <788> requirements for subvisible particulates. Using these vials helps maintain the integrity of the 0.9 % benzyl‑alcohol solution, especially when the vials are refrigerated after puncture.
How long does it take to receive an order of bacteriostatic water?
Orders placed before 2:00 PM Central Time, Monday through Friday, are processed and shipped the same business day from the Dallas, TX fulfillment center. Shipping is via standard US carrier without a cold‑chain, and unopened vials are stored at controlled room temperature (15–30 °C) during transit. Delivery typically occurs within 2–3 business days, depending on the destination.
What pricing options are available for bulk purchases?
BAC Water Depot sells single vials for $9.99 each. Tiered pricing reduces the per‑vial cost: a 10‑pack is $74.99 ($7.49 per vial), a 25‑pack is $174.99 ($6.99 per vial), and larger bulk orders (25–49 vials) cost $7.49 per vial, 50–149 vials $6.99, 150–499 vials $6.74, and 500+ vials $6.49 each. Free standard shipping is offered on orders over $250, up to 100 vials.
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