Bacteriostatic Water: The $20 Vial That Decides Whether Your Peptide Survives
Every lyophilised peptide you buy is inert powder until it is reconstituted — and what you reconstitute it with determines whether it lasts a week or a month. Sterile water is not the same thing. Here is why, and why it belongs in every order.
- Bacteriostatic water is sterile water containing 0.9% benzyl alcohol, a preservative that suppresses bacterial growth and makes a vial multi-use.
- Sterile water and water for injection contain no preservative — once the stopper is pierced, the contents should be treated as single-use.
- Every lyophilised peptide in this catalogue arrives as inert powder and does nothing until reconstituted. The diluent is not an optional accessory.
- A reconstituted peptide stored at 2-8 degrees C is generally stable for a matter of weeks; the exact window is compound-specific and stated on the certificate of analysis.
- Popular Peptides supplies USP-grade bacteriostatic water in a 10 ml multi-use vial, shipped from Vancouver with the rest of your order.
- For in vitro laboratory research use only — not for human or veterinary consumption.
The cheapest thing in your order is also the one that decides whether the rest of it works
You can spend a lot on a high-purity peptide, have it independently tested, have the certificate of analysis in hand — and still waste the vial, because you reconstituted it with the wrong diluent or ran out of the right one mid-experiment.
Lyophilised peptide is inert powder. It does nothing until it goes into solution. What you put it into is not an accessory purchase; it is half the experiment.
Add bacteriostatic water to your order — it ships in the same box, from Vancouver, and costs less than any other line on your invoice.
Bacteriostatic water vs sterile water: the difference that matters
They look identical. They are not interchangeable.
**Sterile water for injection** is exactly that: water, sterilised, nothing added. It contains no preservative. The moment the stopper is pierced, there is nothing in the vial suppressing microbial growth. Best practice treats it as single-use — draw once, discard the remainder.
**Bacteriostatic water** is sterile water with **0.9% benzyl alcohol** added. Benzyl alcohol is a bacteriostatic preservative: it does not sterilise the contents, but it inhibits the multiplication of bacteria introduced during repeated stopper punctures. That single ingredient is what converts a one-shot vial into a multi-use one.
For any research workflow where a reconstituted compound is drawn from more than once, that distinction is the whole ballgame. Reconstitute a 10 mg vial with sterile water, use a fraction of it, and store the rest, and you are storing an unpreserved aqueous solution. Do the same with bacteriostatic water and you have a preserved one.
What this means in practice
- —**Reconstitution volume sets your concentration.** 10 ml of diluent into a 10 mg vial gives 1 mg/ml. Choose the volume for the concentration your protocol needs, not out of habit.
- —**Add the water gently down the vial wall.** Do not inject a direct stream into lyophilised cake and do not shake. Peptides are structurally fragile; froth means denatured material. Swirl, or leave it to dissolve.
- —**Refrigerate after reconstitution.** 2-8 degrees C, protected from light. Stability in solution is measured in weeks, not months, and the specific window varies by compound — check the certificate of analysis for the batch you actually received.
- —**Avoid repeated freeze-thaw cycles.** Each one costs you material.
- —**Lyophilised powder is the stable form.** Stored at -20 degrees C, dry and dark, unreconstituted peptide keeps far longer than anything in solution. Reconstitute what you will use.
For the full bench procedure — equipment, step-by-step reconstitution and worked concentration examples — see our technical guide to reconstituting peptides. For compound-by-compound handling notes, the peptide reference library lists storage guidance per compound, and the peptide calculator does the arithmetic for you.
Why buy it here rather than wherever
Because it arrives with everything else, from inside Canada, and because the alternative is worse than people assume.
Bacteriostatic water bought from an offshore supplier crosses a border, which means it is subject to the same customs risk as everything else in that package — and a seized shipment does not care that the cheapest item in it was the water. Buying it domestically as an afterthought from a third party means a second shipment, a second wait, and a second chance for something to go wrong.
Ours is **USP-grade, 10 ml, multi-use**, and it ships from Vancouver, BC with the rest of your order — typically 2 to 5 business days, tracked, insured and discreetly packaged. Free shipping over $300 CAD. Priced and charged in Canadian dollars, with card or Interac e-Transfer at checkout.
If you are ordering any lyophilised compound, order the water with it. Running out mid-protocol is an entirely avoidable way to lose a week.
Add Bacteriostatic Water 10 ml
Frequently asked questions
What is bacteriostatic water?
Bacteriostatic water is sterile water containing 0.9% benzyl alcohol as a preservative. The benzyl alcohol inhibits bacterial growth, which allows the vial to be punctured and drawn from multiple times rather than being discarded after a single use.
Can I use sterile water instead of bacteriostatic water?
They are not equivalent. Sterile water contains no preservative, so once the stopper is pierced there is nothing suppressing microbial growth and the contents should be treated as single-use. Bacteriostatic water is the appropriate choice wherever a reconstituted vial will be drawn from more than once.
How much bacteriostatic water do I use to reconstitute a peptide?
The volume sets the final concentration: 10 ml into a 10 mg vial yields 1 mg/ml, 2 ml into the same vial yields 5 mg/ml. Choose the volume that gives the concentration your protocol requires. Our peptide calculator works this out for you.
How long does a reconstituted peptide last?
Generally a matter of weeks when stored at 2-8 degrees C, protected from light, though the exact window is compound-specific. The certificate of analysis for your batch states the guidance for that compound. Unreconstituted lyophilised powder stored at -20 degrees C keeps considerably longer.
Where can I buy bacteriostatic water in Canada?
Popular Peptides supplies USP-grade bacteriostatic water in 10 ml multi-use vials, shipped domestically from Vancouver, BC alongside the rest of your order. It is supplied for laboratory research use only.
Bacteriostatic Water is supplied for in vitro laboratory research use only. It is not intended for human or veterinary consumption. 18+.
Every batch we sell is independently third-party tested, with the full Certificate of Analysis published and checkable by lot number.