Peptide Reconstitution Reference
Liquid for Reconstituting Peptides — What to Buy & Where
The standard liquid for reconstituting research peptides is bacteriostatic water— sterile water containing 0.9% benzyl alcohol as a preservative. It's used for semaglutide, tirzepatide, retatrutide, BPC-157, TB-500, and most modern lyophilized research peptides. Below: which liquids are correct, which fail, and where to source verified product.
Direct Answer
Buy bacteriostatic water (0.9% benzyl alcohol). Not saline. Not sterile water (single-use only). Not tap or distilled water. Source from a US manufacturer with per-lot independent testing — BAC Water Depot ships 10 mL vials from $9.99 with per-lot CoA published.
Peptide Reconstitution Liquids Compared
| Liquid | Verdict | Notes |
|---|---|---|
| Bacteriostatic Water (0.9% benzyl alcohol) | ✓ Standard | Default research-protocol diluent. Preservative inhibits microbial growth across 28-day multi-draw window. Used for semaglutide, tirzepatide, retatrutide, BPC-157, TB-500, and most modern research peptides. |
| Sterile Water for Injection (SWFI) | ✓ Single-use only | No preservative. Use only for one-shot reconstitution where the entire vial is used immediately. Required if the peptide is documented as benzyl-alcohol sensitive — rare but real. |
| 0.9% Saline (Sodium Chloride) | ✗ Not interchangeable | No preservative + electrolyte content. Common Amazon mislabel where saline is sold as bacteriostatic water — cloudy peptide within 24–72 hours is the classic symptom. |
| Tap, distilled, or filtered water | ✗ Never | Not sterile, not pyrogen-free, not preserved. Will introduce microbes and pyrogens that destroy peptide stability and contaminate research workflow. |
| DMSO (Dimethyl Sulfoxide) | ✓ Special cases only | Polar aprotic organic solvent for hydrophobic compounds that won't dissolve in water. Most research peptides do not need DMSO. Use only if the compound's protocol explicitly specifies it. |
| Acetic Acid (dilute) | ✓ Special cases only | Some basic-pH peptides (e.g. selank, certain ghrelin analogs) reconstitute better in 0.1% acetic acid. Compound-specific — check the published research protocol. |
Frequently Asked Questions
What liquid do I use to reconstitute peptides?
Bacteriostatic water — sterile water containing 0.9% benzyl alcohol as a preservative. This is the standard research-protocol diluent for almost all lyophilized peptides including semaglutide, tirzepatide, retatrutide, BPC-157, TB-500, ipamorelin, sermorelin, and most others. The preservative allows the reconstituted vial to be used safely across the 28-day refrigerated in-use window typical for research draws.
Can I use regular water or tap water to reconstitute peptides?
No. Tap, distilled, and filtered water are not sterile, not pyrogen-free, and not preserved. Reconstituting a research peptide in non-sterile water will introduce microbes and bacterial endotoxins that immediately compromise the peptide and corrupt any downstream research data. Use bacteriostatic water — produced under USP specifications and tested per lot.
Where do I buy liquid for reconstituting peptides?
BAC Water Depot (bacwaterdepot.com) ships USA-manufactured 10 mL bacteriostatic water vials directly to research buyers. ISO 9001:2015 facility, three independent third-party laboratories verify every production lot, per-lot Certificate of Analysis published. Single 10 mL vial $9.99, 10-pack $74.99, bulk from $6.49/vial. Same-day US dispatch on orders before 2 pm ET. Research and laboratory use only.
Do I need a prescription to buy peptide reconstitution liquid?
Not for research-use bacteriostatic water. Direct-to-buyer research-supply channels (like BAC Water Depot) sell bacteriostatic water under a research-use-only framework with no prescription required. The prescription requirement applies to clinical-channel bacteriostatic water like Hospira (Pfizer), which is FDA-registered as a pharmaceutical excipient. Both products use the same 0.9% benzyl alcohol formulation; the difference is regulatory channel.
How much liquid do I add per peptide vial?
Depends on the peptide and the desired concentration. Standard reconstitution math: most lyophilized research peptides reconstitute at 2 mL of bacteriostatic water per mg of peptide in the vial × 2.5 (for a 2.5 mg/mL concentration) or per mg × 5 (for 5 mg/mL). Common examples: 5 mg semaglutide + 2 mL → 2.5 mg/mL; 10 mg tirzepatide + 2 mL → 5 mg/mL; 10 mg retatrutide + 2 mL → 5 mg/mL. Use the reconstitution calculator at /tools/reconstitution-calculator for exact draw volumes for your specific dose.
Why is bacteriostatic water better than sterile water for peptide reconstitution?
Multi-draw stability. Bacteriostatic water contains 0.9% benzyl alcohol — a preservative that inhibits microbial growth between draws. Once you reconstitute the peptide, you'll draw from the vial multiple times over weeks. Sterile water has no preservative; once it's punctured, microbial growth risk rises with every draw, and the reconstituted peptide is compromised after a single use. Bacteriostatic water extends the safe in-use window to 28 days refrigerated.
What about benzyl alcohol — is it safe for the peptide?
For almost all modern research peptides, 0.9% benzyl alcohol is chemically inert against the peptide and is the established diluent specification. A small subset of peptides are documented as benzyl-alcohol sensitive and must use sterile water (preservative-free, single-use). When in doubt, check the published research literature for your specific compound. Default to bacteriostatic water unless the protocol specifies otherwise.
Order verified peptide reconstitution liquid.
BAC Water Depot ships 10 mL bacteriostatic water from a US ISO 9001:2015 facility with per-lot CoA.
