BAC Water, Reconstitution & Storage
Most research and prescription peptides ship as a lyophilized (freeze-dried) powder that must be reconstituted before injection. Handling the diluent, mixing, and storage correctly is what determines whether the compound retains potency — and whether the vial stays sterile across a multi-week protocol.
What Is Bacteriostatic Water
Bacteriostatic water for injection (BAC water) is sterile water preserved with 0.9% benzyl alcohol. The preservative inhibits bacterial growth in a multi-dose vial across repeated needle punctures, which plain sterile water and 0.9% saline do not. It is the standard diluent for peptides intended to be used over days or weeks.
- ·Ships in 10 mL or 30 mL multi-dose vials.
- ·Preferred diluent for CJC-1295, Ipamorelin, BPC-157, TB-500, PT-141, GHK-Cu, and similar research peptides.
- ·Plain sterile water is single-use only — a reconstituted vial must be discarded within ~24 hours.
- ·Some peptides (e.g. glucagon, certain acidic formulations) require a specific diluent per manufacturer; follow the label.
Reconstitution Basics
- Wipe both vial stoppers (peptide + BAC water) with a fresh alcohol swab.
- Draw the desired volume of BAC water into an insulin syringe.
- Inject the BAC water down the side of the peptide vial — do not blast it directly onto the powder.
- Gently swirl until fully dissolved. Never shake — agitation can denature peptides.
- Label the vial with the reconstitution date and concentration.
- Refrigerate immediately.
Concentration (mg/mL) = vial strength (mg) ÷ mL of BAC water added.
On a U-100 insulin syringe, 100 units = 1 mL. Example: a 5 mg vial reconstituted with 2 mL BAC = 2.5 mg/mL, so a 250 mcg dose = 10 units.
Pre-Reconstitution — Lyophilized Powder
- ·Room temperature: often stable for weeks (during shipping). Not a long-term option.
- ·Refrigerated 2–8°C: typically 12–24 months.
- ·Frozen –20°C: 2+ years for most peptides. Best for bulk supply.
- ·Keep vials sealed, desiccated, and protected from light and humidity.
- ·Frozen powder can be thawed and refrigerated without loss of potency — do not repeatedly freeze/thaw.
Post-Reconstitution — Mixed Vial
- ·Refrigerate 2–8°C only. Never leave at room temperature long-term.
- ·With BAC water: typical usable window is up to 28 days (peptide-specific — see each detail page).
- ·With plain sterile water or saline: ~24 hours, then discard.
- ·Do not freeze after reconstitution. Ice crystals denature most peptides.
- ·Protect from light — copper peptides (GHK-Cu), melanocortins (PT-141, Melanotan II), and CJC-1295 are especially sensitive.
- ·Discard immediately if you see cloudiness, discoloration, precipitate, or if the vial has been contaminated.
Storing BAC Water Itself
- ·Sealed vial: store at room temperature (below 25°C), away from light, until first puncture.
- ·After first puncture: refrigerate and use within 28 days per USP guidance. Discard after that.
- ·Always wipe the stopper with alcohol before each draw. Never reuse a needle across vials.
Safety Notes
- ·Use a fresh sterile needle for every injection. Never share vials.
- ·Benzyl alcohol is contraindicated in neonates and should be avoided during pregnancy and breastfeeding — use plain sterile water and single-use dosing.
- ·Rotate injection sites; clean the site with alcohol and let it dry before injecting.
- ·Dispose of used needles in a sharps container.
Disclaimer
Educational reference only. Not medical advice. Storage and reconstitution guidance varies by peptide, formulation, and jurisdiction — always follow the manufacturer's package insert and consult a qualified clinician.