What Is Bacteriostatic Water?
Bacteriostatic water is sterile water for injection containing 0.9% benzyl alcohol as a bacteriostatic preservative. It is the standard reconstitution solvent for research peptides — the liquid used to dissolve lyophilized (freeze-dried) peptide powder into a solution at a known concentration suitable for research use. The “bacteriostatic” designation refers to benzyl alcohol’s ability to inhibit microbial growth in the reconstituted solution, dramatically extending its usable stability compared to plain sterile water.
The distinction between bacteriostatic water and plain sterile water matters significantly in research settings. A vial reconstituted with plain sterile water is vulnerable to microbial contamination and should be used within 24–48 hours. A vial reconstituted with bacteriostatic water — where benzyl alcohol suppresses bacterial and fungal growth — remains stable for 4–6 weeks when stored at 2–8°C. For research protocols spanning days to weeks, bacteriostatic water is not optional — it is the practical requirement for maintaining solution integrity across the study duration.
Why Hospira Specifically?
Pharmaceutical-Grade Manufacturing
Not all bacteriostatic water is equivalent. Hospira (now a Pfizer company) is the dominant manufacturer of pharmaceutical-grade bacteriostatic water for injection in the United States — producing under FDA-regulated Current Good Manufacturing Practice (cGMP) standards that govern sterility testing, endotoxin limits, container closure integrity, and chemical purity. This regulatory oversight means every Hospira vial meets defined specifications for water purity, benzyl alcohol concentration (0.9% ± established tolerances), pH, and sterility — specifications that are tested and documented in batch records.
The Research Community Standard
Hospira Bacteriostatic Water has become the de facto standard in the research peptide community for a straightforward reason: it is what hospital pharmacies, compounding pharmacies, and pharmaceutical manufacturers use. When a research protocol specifies “bacteriostatic water for injection,” Hospira is what that means in practice. Using the same grade of solvent that appears in the published research literature — rather than a generic or unknown-provenance alternative — is part of what makes research protocols reproducible and comparable to published work.
Multi-Dose Vial Format
Hospira Bacteriostatic Water is supplied in multi-dose vials — designed to be accessed multiple times through the rubber septum without compromising sterility, because benzyl alcohol prevents the microbial contamination that would otherwise occur when a vial is repeatedly punctured. This multi-dose design is specifically suited to peptide research applications where a single vial of bacteriostatic water may be used to reconstitute multiple peptide vials across days or weeks.
How Bacteriostatic Water Is Used in Peptide Research
Reconstitution
The primary use is reconstitution — dissolving lyophilized peptide powder into solution. The process is straightforward: draw the calculated volume of bacteriostatic water into a sterile syringe, inject it slowly down the side wall of the peptide vial, and gently swirl until the powder dissolves. The resulting solution is at a known concentration determined by the mass of peptide in the vial divided by the volume of bacteriostatic water added. For precise reconstitution calculations across any vial size and target concentration, use the AminoForge peptide calculator. For the complete step-by-step reconstitution process, see our How to Reconstitute Peptides guide.
Why the Benzyl Alcohol Concentration Matters
The 0.9% benzyl alcohol concentration in Hospira Bacteriostatic Water is the established pharmaceutical standard that balances bacteriostatic efficacy with compatibility across a wide range of peptide compounds. Benzyl alcohol at this concentration inhibits growth of the most common contaminating bacteria and fungi — Staphylococcus aureus, E. coli, Pseudomonas aeruginosa, Candida albicans — without significantly affecting the chemical stability of most research peptides. For researchers working with cell culture applications where benzyl alcohol may be cytotoxic at certain concentrations, PBS is the appropriate alternative, and Acetic Acid Water serves as a co-solvent for hydrophobic peptides that require initial dissolution in acidic conditions.
What Peptides Pair with Hospira Bacteriostatic Water?
Bacteriostatic water is the reconstitution solvent for virtually all lyophilized research peptides. The most commonly paired compounds at AminoForge include:
Tissue Repair Research
BPC-157 — one of the most researched regenerative peptides, studied for tissue repair, angiogenesis, and cytoprotection. Available in 5mg and 10mg vials. See our BPC-157 Dosage & Reconstitution Guide for precise reconstitution calculations. Also: TB-500, GHK-Cu, Wolverine Blend, GLOW Blend.
GH Axis Research
Ipamorelin, CJC-1295 No DAC, CJC-1295 With DAC, Sermorelin, Tesamorelin, IGF-1 LR3. For the most common GH axis combination, see our CJC-1295 + Ipamorelin research guide.
Metabolic and GLP-1 Research
Semaglutide, Tirzepatide, Retatrutide, Cagrilintide, MOTS-C, AOD-9604.
Longevity Research
Epitalon, SS-31, FOXO4-DRI, NAD+, Thymalin. See our Best Peptides for Longevity Research guide for compound selection rationale.
Cognitive and Neuropeptide Research
Semax, Selank, Dihexa, Pinealon, DSIP.
Storage and Handling of Bacteriostatic Water
Before Opening
Store unopened Hospira Bacteriostatic Water vials at room temperature or refrigerated — per Hospira’s product labeling, storage between 15–30°C (59–86°F) is appropriate for unopened vials. Avoid freezing, which can compromise container closure integrity, and protect from direct light.
After Opening
Once a vial has been accessed, the benzyl alcohol preservative maintains sterility through multiple punctures — this is the entire purpose of the multi-dose vial design. Accessed vials should be stored at room temperature or refrigerated and used within 28 days per standard pharmaceutical multi-dose vial guidelines. Label the vial with the first-access date.
Reconstituted Peptide Solutions
Peptide solutions reconstituted in Hospira Bacteriostatic Water should be stored at 2–8°C (refrigerator temperature), protected from light. Most research peptides are stable in bacteriostatic water for 4–6 weeks under these conditions. For compound-specific stability data and what actually determines peptide degradation, see our science-backed Peptide Storage and Handling Guide.
Common Questions About Bacteriostatic Water
Can I use regular sterile water instead?
Yes, but reconstituted solutions must be used within 24–48 hours due to contamination risk without the bacteriostatic preservative. For any multi-day research protocol, bacteriostatic water is the appropriate choice.
Is bacteriostatic water the same as saline?
No. Bacteriostatic water contains 0.9% benzyl alcohol in water. Normal saline (0.9% NaCl) contains sodium chloride in water with no bacteriostatic agent. They have different applications — bacteriostatic water is the standard for peptide reconstitution; saline is used for dilution in some protocols but is not the preferred primary reconstitution solvent for most research peptides.
How much bacteriostatic water do I need?
This depends on how many vials you are reconstituting and your target concentrations. A single 30mL Hospira vial contains enough bacteriostatic water to reconstitute dozens of peptide vials at typical working volumes (0.5–2mL per vial). Use the peptide calculator to determine the exact volume needed for each vial.
Where can I buy Hospira Bacteriostatic Water?
AminoForge carries pharmaceutical-grade Hospira Bacteriostatic Water — the same standard used in research laboratories and clinical settings. Ships within 48 hours alongside your research peptide order.
For further reading on peptide reconstitution and stability science see: Peptide and protein stability in pharmaceutical formulations (PubMed).
Shop Hospira Bacteriostatic Water at AminoForge — pharmaceutical grade, ships within 48 hours. Also available: PBS and Acetic Acid Water for specialized reconstitution needs.
All products sold by AminoForge are intended exclusively for laboratory and research purposes. Not for human or veterinary consumption. Researchers are responsible for compliance with all applicable laws and regulations governing research compound use in their jurisdiction.