How to Reconstitute Peptides in 2026: Step-by-Step + Dosing Math

What is bacteriostatic water?

Bacteriostatic water (BAC water) is sterile water with roughly 0.9% benzyl alcohol added as a preservative. The preservative suppresses bacterial growth, which is what lets a reconstituted vial be used across multiple draws over several weeks when refrigerated. Sterile water and standard saline lack that preservative and are generally not used for multi-draw reconstitution.

Step-by-step reconstitution

1. Let the peptide vial and BAC water reach room temperature; wipe both stoppers with alcohol.
2. Draw your chosen volume of BAC water into the syringe before touching the powder.
3. Add the water slowly, aiming the stream down the inside wall of the vial rather than blasting the powder directly.
4. Swirl or roll gently until fully dissolved — do not shake hard, which can damage the peptide.
5. Refrigerate the reconstituted vial and protect it from light.

The concentration formula

The peptide distributes evenly through whatever water you add, so:

Concentration (mg/mL) = milligrams in the vial ÷ millilitres of BAC water added.

Common protocols use 1–3 mL of BAC water per vial. More water = a more dilute solution and larger, easier-to-measure draws; less water = a more concentrated solution and smaller draws.

Worked example (with syringe units)

On a U-100 insulin syringe, 100 "units" = 1 mL, so each unit = 0.01 mL. A 5 mg vial in 2 mL gives 2.5 mg/mL = 25 mcg per unit, so a 250 mcg research dose is 10 units.

Common mistakes to avoid

• Shaking the vial hard instead of swirling.
• Injecting the water stream straight onto the powder.
• Forgetting that concentration depends on the water you chose — always recompute mcg/unit after mixing.
• Storing at room temperature; reconstituted peptides belong in the fridge, away from light.

Where to get BAC water and reconstitution solution

Many of the 26 vendors PepsTracker tracks sell bacteriostatic water and reconstitution solution alongside their peptides — for example, Platinum Peptides stocks reconstitution solution, and PepsTracker users get 15% off with code pepstracker15. Compare BAC water and any compound on live cost-per-mg pricing across all vendors on the PepsTracker homepage.

Frequently asked questions

How much bacteriostatic water do I add to a peptide vial?

Most protocols use 1–3 mL per vial. The exact amount is your choice — it sets the concentration. Concentration equals the milligrams in the vial divided by the millilitres of water you add.

How do I calculate the dose in syringe units?

On a U-100 syringe, 100 units = 1 mL. Compute concentration (mg ÷ mL), convert to mcg per unit, then divide your target dose by that number. A 5 mg vial in 2 mL is 25 mcg/unit, so 250 mcg = 10 units.

Can I use regular or sterile water to reconstitute peptides?

Bacteriostatic water is preferred for multi-draw vials because its benzyl alcohol preservative suppresses bacterial growth. Plain sterile water has no preservative and is generally used only for single-use scenarios.