Quick answer
Bacteriostatic water (BAC water) is sterile water with a small amount of benzyl alcohol preservative. Researchers add it to lyophilized peptide vials to make a liquid concentration for measurement. CoreVials BAC water and peptides are for laboratory research only.
If the powder in a vial is the compound, BAC water is the liquid that turns it into a measurable solution. The volume you add sets mg per ml. That number drives every syringe unit calculation afterward.
Use the visual reconstitution calculator when you want the unit math drawn out. For GLP-1 style walkthroughs, see the tirzepatide and retatrutide beginner guides.
What is BAC water?
BAC water is sterile water plus benzyl alcohol (commonly about 0.9% in research-supply descriptions). The preservative is why multi-draw lab use is discussed differently than single-use sterile water.
It is still a lab reagent. It is not a medicine, and it does not change what the peptide itself is.
Concentration math in one minute
Concentration = total mg in the vial ÷ ml of BAC water added.
- 10 mg peptide + 1 ml BAC water = 10 mg/ml
- 10 mg peptide + 2 ml BAC water = 5 mg/ml
On a U-100 insulin-style syringe, 100 units = 1 ml. So if your mix is 10 mg/ml, then 10 units is 0.1 ml and delivers 1 mg of peptide in that example.
Clean reconstitution habits
- Wipe stoppers with alcohol and let them dry
- Inject BAC water slowly down the glass wall, not as a hard jet onto the cake
- Swirl gently. Do not shake foamy solutions
- Label concentration, date, and lot on the vial or notebook
- Follow your lab cold-storage SOP after reconstitution
Research boundary: These steps are laboratory handling notes. They are not personal medical instructions. Products are not for human or animal consumption. See research compliance.
Bottom line
- BAC water reconstitutes lyophilized research vials
- ml added sets mg/ml
- U-100: 100 units = 1 ml
- Write the concentration down before the first draw
References
- USP compounding and sterile preparation principles for aqueous dilutions (institutional lab SOPs should control local practice).
- CDC / pharmacy sterile technique summaries for alcohol swabbing and multi-dose vial handling in laboratory settings.
