How to Mix Peptides with Bacteriostatic Water

If you’ve never worked with pure peptide compounds before, one of the first things you’ll come across is the term “bacteriostatic water,” often shortened to “bac water.” It’s not just regular water or distilled water. Bac water ensures your peptide’s stability, sterility, and effectiveness. 

Bacteriostatic water is sterile water that contains 0.9% benzyl alcohol to inhibit bacterial growth, distinguishing it from regular sterile water. Bac water is what’s used to dilute or dissolve injectable medications — including peptides — with the added benefit of preserving the solution and allowing safe use over multiple doses, typically up to 28 days when stored properly.

What Water Should Be Mixed with Peptides?

Only use bacteriostatic water that contains 0.9% benzyl alcohol to reconstitute your peptides. Most peptide vials come in a lyophilized (freeze-dried) powder that needs to be mixed with bac water before you can inject it.

The benzyl alcohol in bac water prevents bacterial growth inside the vial, which is important because once you puncture a vial, it’s no longer a completely sterile environment.

If you’re using multi-dose vials of peptides over days or weeks, bac water keeps your solution stable for up to 28 days when stored properly in the fridge.

How To Use Bac Water for Peptides

  • Clean your workspace: Wipe down your working area with alcohol and wash your hands thoroughly.
  • Disinfect vial tops: Use alcohol wipes to clean both the bac water vial and the peptide vial before puncturing.
  • Draw bac water: Attach a sterile needle and syringe, insert into the bac water vial, and draw the desired amount to the correct ratio (usually listed in your peptide’s instructions).
  • Inject into peptide vial: Insert the needle into the peptide vial at a slight angle, allowing the water to run down the inner wall. Avoid spraying directly onto the powder to prevent foaming, which could agitate the peptide and cause degradation.
  • Dissolve the peptide: Gently swirl or roll the vial between your fingers until the powder fully dissolves. Never shake, as vigorous motion can damage the peptide’s structure.
  • Label and store: Write the date of reconstitution on the vial. Store in the refrigerator (2–8°C) and use within 28 days.

Where To Buy Bac Water

You can find bacteriostatic water online and in pharmacies. Some peptide suppliers include it with your order, while others sell it separately.

Trusted places to buy include:

  • Amazon – Widely available, but ensure it’s from a reputable, U.S.-based medical supplier.
  • MedLab Supply – Specializes in research-grade materials and ships quickly.
  • Peptide Sciences or Core Peptides – Often carry bac water that pairs with peptide orders.
  • Local Pharmacy – Some compounding pharmacies sell bac water if you ask at the counter.

Safety Precautions

Even when using bac water, you need to keep your environment as sterile as possible when working with peptides.

Always clean vial tops with alcohol swabs before puncturing them to prevent contamination, and always use a fresh needle for every draw.

After mixing, store your peptide vials in the refrigerator to maintain stability and discard after 28 days.

You never want to mix bac water with tap or distilled water, as this can introduce impurities that compromise sterility and make it unsafe for injection.

Do You Need Bac Water with Stem Code Peptides?

Not for Stem Code peptides. All Stem Code peptides come pre-formulated as stabilized tablets or nasal sprays, so there’s no need for bac water.

These delivery methods are ready to work with, shelf-stable, and designed for precision dosing — no mixing, needles, or reconstitution required.