Bacteriostatic water only. Not sterile water for injection. Not saline. Not distilled water. Not tap water. Bacteriostatic water (BAC water) contains 0.9% benzyl alcohol which prevents bacterial growth in your reconstituted vial. Without it, a reconstituted peptide vial becomes a bacterial growth medium within 24 hours at refrigerator temperature.
Step-by-Step Reconstitution
1
Gather everything before you start
Peptide vial, bacteriostatic water vial, alcohol swabs, new syringe (1ml or 3ml for reconstitution — not your insulin syringe), your injection syringe, sharps container. Having everything laid out before you start prevents rushed movements with needles in hand.
2
Swab both vial tops
Wipe the rubber septum of both your peptide vial and your BAC water vial with a fresh alcohol swab. Single outward motion — not back and forth. Wait 10 full seconds for the alcohol to evaporate completely. Injecting through wet alcohol drives it into the vial.
3
Inject air into the peptide vial first Important step
Peptide vials are vacuum-sealed from the lyophilisation process. Without pressure equalisation, injecting BAC water is difficult and withdrawing the solution afterwards is even harder. Before drawing up BAC water: draw up the same volume of air you plan to inject (e.g. if adding 2ml BAC water, draw up 2ml of air). Insert the needle into the peptide vial septum and inject the air. This equalises the pressure — making injection smooth and extraction effortless. Never skip this step.
4
Draw up your bacteriostatic water
Using a fresh syringe, draw up the calculated amount of BAC water. Typical reconstitution volumes: 1–2ml for most peptide vials. Use the calculator on the Preparation & Safety guide to determine your target concentration. A 5mg vial + 2ml BAC water = 2500mcg/ml.
5
Inject water down the side of the vial Critical
Insert the needle at an angle so it touches the inner glass wall of the peptide vial — not the powder directly. Depress the plunger slowly, letting the water run down the glass wall and dissolve the powder gently. Never inject directly onto the powder with force. The mechanical disruption of forced water directly onto lyophilised peptide destroys the structure and reduces potency.
6
Roll — never shake Never shake
Gently roll the vial between your palms. The powder will dissolve within 30–60 seconds for most peptides. If it does not dissolve fully, allow the vial to sit for 2–3 minutes — never force it with agitation. A fully reconstituted peptide should be completely clear with no visible particles or cloudiness.
7
Inspect before use
Hold the vial up to a light source. The solution should be completely clear and colourless. Any cloudiness, colour (yellow, brown), or visible particles indicates either contamination or a degraded peptide. Do not inject — discard the vial.
8
Label and refrigerate immediately
Write the date of reconstitution on the vial label with a permanent marker. Refrigerate immediately at 2–8°C. Most reconstituted peptides are stable for 4–6 weeks refrigerated with bacteriostatic water. See the storage guide for compound-specific guidance.