Where to Buy BAC Water for Peptide Reconstitution
Research laboratories source bacteriostatic water (BAC water) from specialist research suppliers like Peptx rather than retail pharmacies, which rarely stock the multi-dose 30mL format needed for peptide reconstitution. Peptx ships BAC water worldwide with tracked delivery.
ToolPeptide Reconstitution Calculator
Work out concentration, draw volume and U-100 syringe units from a vial mass and the volume of bacteriostatic water added.
What bacteriostatic water actually is
Bacteriostatic water for injection (BWFI) is sterile water that has been treated with 0.9% benzyl alcohol, a mild bacteriostatic preservative. The preservative does not actively kill bacteria, but it prevents microbial growth within the vial, allowing the same multi-dose vial to be safely punctured and used repeatedly for up to 28 days after first opening.
In research-peptide work, lyophilised peptides arrive as a dry powder that must be reconstituted before use. Bacteriostatic water is the standard diluent for this because laboratory work often draws from a single reconstituted vial over multiple weeks, and the bacteriostatic preservative allows that workflow without microbial contamination risk. Plain sterile water for injection, by contrast, is single-use only and must be discarded after first puncture.
The 30mL multi-dose format that Peptx supplies is the workhorse size used across virtually all published peptide research protocols. One 30mL vial typically supports 10 to 30 separate peptide vial dilutions depending on the concentration used.
How to use bacteriostatic water for peptide reconstitution
1. Calculate the volume
Concentration is determined by the diluent volume added relative to the peptide mass stated on the vial label, expressed in mg per mL.
2. Add the diluent slowly
Add the calculated volume of bacteriostatic water slowly down the inner wall of the vial, never directly onto the lyophilised powder, which can denature delicate sequences.
3. Swirl, do not shake
Gently swirl the vial in a circular motion until the powder fully dissolves. Vigorous shaking can degrade peptide chains and introduce foaming. The solution should be visually clear when ready.
4. Refrigerate and label
Refrigerate the reconstituted vial at 2 to 8 Celsius. Label with the reconstitution date and the achieved concentration. Most reconstituted research peptides are stable refrigerated for 4 to 6 weeks.
Storage and shelf life
- Unopened vials: stable at room temperature, away from direct sunlight, for the full labelled shelf life.
- After first puncture: store refrigerated at 2 to 8 Celsius. Discard any unused portion 28 days after first puncture, per standard USP multi-dose guidance.
- Reconstituted peptide vials: store refrigerated at 2 to 8 Celsius, protected from light, and use within 4 to 6 weeks for most research peptides.
- Visual checks: the solution should remain clear and colourless. Discard any vial showing cloudiness, particulate matter, or discolouration.