Two vials of clear liquid, two very different jobs. Bacteriostatic water and sterile water are both laboratory diluents, but they are not interchangeable, and knowing the difference is basic lab literacy for anyone working with research materials.
Sterile water
Sterile water is water that has been sterilized and packaged free of viable microorganisms. It contains no preservative. That matters: once the container is opened, there is nothing in the water to suppress microbial growth. In laboratory practice it is treated as single-use; whatever is not used promptly is discarded.
Bacteriostatic water
Bacteriostatic water is sterile water with 0.9% benzyl alcohol added as a bacteriostatic preservative. The benzyl alcohol does not sterilize anything; it inhibits the growth of most common bacteria inside the vial after the first entry. That is the entire point of the product: it is designed for laboratory workflows that require multiple withdrawals from the same vial over a period of days or weeks rather than a single use.
The practical differences
- Preservative. Bacteriostatic water: 0.9% benzyl alcohol. Sterile water: none.
- Multiple entries. Bacteriostatic water tolerates repeated vial entries in laboratory use; sterile water is treated as single-use once opened.
- Shelf life after opening. Laboratory convention treats an opened bacteriostatic vial as usable for a limited window (commonly cited as up to 28 days under proper storage); an opened sterile-water vial is not stored for reuse.
- Compatibility. Benzyl alcohol is not appropriate for every assay; protocols sensitive to preservatives specify preservative-free diluents.
Storage and handling
Both products are stored at room temperature and protected from light. As with any laboratory material, the vial label and the supplier's documentation govern: check the lot number, check the stated composition, and record what you used.
Which one a laboratory should stock
Most research workflows that involve reconstituting lyophilized materials for bench work standardize on bacteriostatic water for its multi-entry tolerance, and keep preservative-free sterile water on hand for preservative-sensitive protocols. Our catalog carries lot-numbered bacteriostatic water (10 ml, 0.9% benzyl alcohol) with its documentation published in the COA ledger as testing completes.
All products sold by Revoryn Labs are intended for laboratory and in-vitro research use only. They are not for human or veterinary use.
For laboratory and in-vitro research use only. Not for human or veterinary use. See our research-use disclaimer.
