What Is Bacteriostatic Water?
Bacteriostatic water is water for injection (WFI) preserved with 0.9% benzyl alcohol, which inhibits bacterial growth so a vial can be accessed more than once without being discarded after a single draw. It’s the standard diluent used across research laboratories for reconstituting lyophilised (freeze-dried) compounds into solution.
Unlike single-draw sterile water for injection (SWFI), the benzyl alcohol preservative in bacteriostatic water is what allows a multi-dose vial to remain viable for repeated use in a laboratory setting, provided aseptic technique is used for every draw.
This 30ml bacteriostatic water is supplied strictly for in-vitro laboratory and research use. It is not manufactured, labelled, or supplied for human or animal administration, diagnostic use, or any clinical purpose.
What’s Included in The 30ml Bac Water?
- Vial size: 30ml
- Physical form: sterile liquid, clear and colourless
- Composition: Water for Injection with 0.9% w/v benzyl alcohol preservative
- Included documentation: batch-specific Certificate of Analysis (COA) available on request
Technical Specifications of The Bacteriostatic Water 30ml
| Specification | Details |
|---|---|
| Diluent | Water for Injection (WFI) |
| Product | Bacteriostatic Water |
| Preservative | Benzyl alcohol, 0.9% (9 mg/mL) |
| Preservative CAS Number | 100-51-6 |
| Vial Volume | 30ml |
| Container | Vial |
| Form | Sterile liquid |
| Use classification | Laboratory and research use |
| Appearance | Clear, colourless liquid |
| Pyrogen status | Non-Pyrogenic |
Who This Bac Water 30ml Size Is For?
The 30ml vial is the right choice for labs and researchers who:
- Run high-throughput reconstitution work across multiple compounds or projects
- Support several researchers or workstations from a shared diluent stock
- Want the lowest cost per ml across the range
- Order regularly enough that a larger vial reduces re-ordering frequency and shipping overhead
If you’re testing a new protocol at small scale, the 3ml or 10ml sizes may reduce open-vial wastage, see the comparison below.
| Size | Best For | Relative Cost per ml |
|---|---|---|
| 3ml | Small-scale or single-project research, minimal open-vial wastage | Higher |
| 10ml | Regular lab use, multiple reconstitutions | Medium |
| 30ml | High-throughput or multi-user laboratory settings | Lower |
Need a larger supply? See our 3ml bacteriostatic water and 10ml bacteriostatic water pages for multi-dose and high-volume options.
How Benzyl Alcohol Preservation Works
The 0.9% w/v benzyl alcohol preservative in this vial works by disrupting the cell membranes of bacteria that may be introduced on each puncture, slowing their growth between draws rather than eliminating them outright. That’s the same concentration set out in the USP monograph for bacteriostatic water for injection, high enough to control a broad range of common contaminants, without altering the solution’s pH or clarity.
In a large, frequently-accessed vial like this one, that preservative effect matters more, not less: with more researchers or sessions drawing from the same stock, the vial is punctured more often, so consistent aseptic technique on every single draw, a clean needle, a disinfected stopper, minimal air exposure, is essential to get the full benefit of the preservative over its full in-use life.
Research Applications
The 30ml size is built for high-throughput or shared laboratory use: reconstituting lyophilised (freeze-dried) research compounds across multiple protocols, supplying more than one workstation from a single preserved stock, or maintaining an ongoing diluent supply for a department rather than a single project. It reduces how often a lab needs to open a fresh vial, which is useful anywhere reconstitution is a routine, repeated part of the workflow rather than a one-off step.
It’s equally suited to preparing larger dilution series or assay batches where a substantial, preserved volume of water needs to stay available on the bench across an extended run.
Storage & Handling
Store unopened vials at controlled room temperature (20–25°C / 68–77°F), away from direct light. Once a vial has been punctured, use aseptic technique for every subsequent draw.
Standard laboratory practice for benzyl alcohol-preserved multi-dose diluents is to limit the in-use period (commonly 28 days from first puncture) to reduce contamination risk, confirm the exact interval against your own laboratory SOP, and see our guide on how long bac water lasts once opened. Do not use if the solution appears cloudy, discoloured, or contains visible particulate.
Certificate of Analysis & Quality Assurance
Each batch is manufactured under controlled, sterile conditions and tested for sterility, endotoxin/pyrogen levels, pH, and benzyl alcohol concentration prior to release. A batch-specific Certificate of Analysis (COA) is available for this product on request, confirming purity, sterility testing, and preservative content for full traceability.
Frequently Asked Questions
What is 30ml bacteriostatic water used for?
In a laboratory setting, it’s used as a diluent to reconstitute lyophilised research compounds into a liquid solution across high-volume or multi-user workflows. It is not intended for human or animal use.
Is the 30ml size better value than the 3ml or 10ml?
Per ml, yes, the 30ml vial typically offers the lowest cost per ml of the three sizes, making it suited to labs with consistent, ongoing reconstitution needs.
What’s the difference between bacteriostatic water and sterile water?
Bacteriostatic water contains 0.9% benzyl alcohol, which inhibits bacterial growth and allows a vial to be used more than once. Sterile (non-bacteriostatic) water for injection has no preservative and is intended for a single draw.
How long does an opened 30ml vial last?
Once punctured, standard practice for benzyl alcohol-preserved multi-dose diluents is to use the vial within roughly 28 days, provided it is stored correctly and accessed aseptically each time. Always follow your lab’s own SOP.
Do you offer wholesale pricing on 30ml vials?
Yes, see our wholesale bacteriostatic water page for bulk pricing and account options.
How should bacteriostatic water be stored?
Store unopened vials at controlled room temperature, away from direct light, and inspect the solution before each use for clarity and the absence of particulate.
What concentration of benzyl alcohol does this product contain?
0.9% w/v benzyl alcohol, in line with standard bacteriostatic water formulations (CAS 100-51-6).
Where can I find the Certificate of Analysis for this batch?
A batch-specific COA is available on request, contact us with your order or batch number.
Scientific References
- Bacteriostatic Water for Injection, USP, FDA-approved prescribing label confirming the 0.9% benzyl alcohol preservative standard for multi-dose bacteriostatic water. DailyMed / U.S. National Library of Medicine. https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=87d6e9dc-fe3b-4593-ac9a-d7493d1959c7
