You can buy bacteriostatic water at a pharmacy, a compounding pharmacy, an online research supplier or a lab distributor. It's one of the few things here with a real local answer. So where to buy bacteriostatic water matters less than what the label says: “Bacteriostatic Water for Injection, USP”, with 0.9% benzyl alcohol as the preservative.
Bacteriostatic water
Referenced in this guideThe Bacteriostatic water referenced throughout this article, supplied as a research compound with a certificate of analysis matched to the lot you receive — the check this site argues you should hold any supplier to.
Bacteriostatic water is sterile water plus 0.9% benzyl alcohol, a mild preservative. It carries a reconstituted peptide vial through a 28-day in-use window at 2–8°C. It’s sold legally in the US as a USP-monographed product, and typical 2026 pricing is $5–$15 per 30 mL vial. The most common sourcing error is getting sterile water or saline instead.
Quick answer: Source a 30 mL vial labeled “Bacteriostatic Water for Injection, USP” with 0.9% benzyl alcohol added on the label. Typical price $5–$15. Avoid anything labeled “sterile water”, which has no preservative and is single-use. Avoid “normal saline” too, which is 0.9% sodium chloride with no preservative.
Where can you buy bacteriostatic water?
Bacteriostatic water is the easy one. Four channels are open: a retail pharmacy, a compounding pharmacy, an online research supplier, and a laboratory chemical distributor. The product is the same substance in all four.
- A retail pharmacy. Pharmacies stock it. Some ask for a prescription, depending on state and pharmacy policy. Many don't, because it's a diluent rather than a drug.
- A compounding pharmacy. Sells the drug-labeled version, “Bacteriostatic Water for Injection, USP”, alongside its other sterile preparations.
- An online research supplier. Sells the same chemical under research-use-only labeling. This is where most people buying peptides pick it up, in the same order.
- A laboratory chemical distributor. The bulk channel, and usually the cheapest per mL if you're buying a case.
We'd treat all four as interchangeable and choose on price and label. There's no scheduling, no 503A category, and no WADA listing to work around.
What is bacteriostatic water?
Bacteriostatic water is sterile water with 0.9% benzyl alcohol added as a preservative, sold in a sealed multi-dose vial that's good for up to 28 days after first puncture. The definition is precise, and the label has to state it. That's the FDA-approved label from 2018.
The 0.9% figure is the regulatory standard. Not 0.5%, not 1%, and not vague “contains benzyl alcohol” copy. At that exact concentration, benzyl alcohol stops bacteria replicating while staying compatible with injection-site tissue.
The mechanism is simple enough. Benzyl alcohol slips into bacterial cell membranes, scrambles their fluidity, and shuts down the membrane-anchored processes bacteria need to replicate. It's gentle enough that the same diluent works across most lyophilized peptide classes without degrading the molecule.
Our reconstitution guide covers the chemistry. This page is the sourcing version: what to look for on the label, what to pay, and the mislabels that catch people out.
How do you identify real bacteriostatic water?
Four questions identify bacteriostatic water. Whether the label states 0.9% benzyl alcohol. Whether it's USP-grade. Whether the in-use window is 28 days. Whether the volume is 30 mL. Most sourcing errors here aren't about quality at all. They're about receiving an entirely different product.
There is no vendor shortlist on this page, and that is deliberate. Our 13 August 2026 supplier survey ranks vendors on certificates of analysis, named testing labs and per-milligram peptide pricing, and none of that transfers to a diluent. Bacteriostatic water is a USP-monographed product, so what you are buying is a label specification rather than a synthesis, and all four channels above sell the same substance. Compare on these four lines instead, then buy on price.
| Label line | Bacteriostatic water | Sterile water (SWFI) | Normal saline |
|---|---|---|---|
| Grade | “Bacteriostatic Water for Injection, USP” | “Sterile Water for Injection” | “0.9% sodium chloride” |
| Preservative | 0.9% benzyl alcohol, named on the label | None | None — here the 0.9% is salt, not preservative |
| Vial size | 30 mL multi-dose vial; 10 mL and 50 mL exist | Usually 1–5 mL single-dose ampules | Single-dose packaging |
| In-use window | 28 days after first puncture at 2–8°C | Single-use once opened | Single-use once opened |
All four lines have to match at once. A vial labeled USP that never names 0.9% benzyl alcohol, or that arrives as a 2 mL ampule, or that carries no in-use statement, is a different product under a similar name. The four checks below are how you read each line.
1. Does the label say “0.9% benzyl alcohol”?
This is the preservative. The number and the substance both have to appear on the label.
Some products marketed as “bacteriostatic” substitute methylparaben, propylparaben or chlorobutanol. Those aren't interchangeable with benzyl alcohol for peptide compatibility. The published literature is anchored on the 0.9% benzyl alcohol standard. Different preservative, different product.
2. Is it USP-grade?
USP stands for United States Pharmacopeia, the body that defines pharmaceutical standards in the US. A USP-grade label means the product meets pharmacopeia rules for identity, purity, sterility and pyrogen content, per USP-NF.
USP also publishes Chapter <797>, the sterile-compounding standard pharmacies follow. Non-USP grades may meet some other standard. They aren't the baseline the published reconstitution research assumes.
3. Is the in-use window 28 days?
This is the operational test. A vial preserved with 0.9% benzyl alcohol stays safe for 28 days after first puncture, stored at 2–8°C and accessed with clean technique. That's the same convention used for human insulin and most preserved injectables, per the ASHP Handbook on Injectable Drugs.
A vendor who won't state the 28-day window is telling you something about their preservative concentration. We'd verify identity before ordering from them.
4. Is the volume 30 mL?
The 30 mL multi-dose vial is the standard size. 10 mL and 50 mL exist for specialty uses. One 30 mL vial covers many lyophilized peptide reconstitutions across a research workflow.
If a vendor only sells 1–5 mL ampules, that's usually preservative-free sterile water in single-dose packaging. Different product, different rules.
Where this falls short: Bacteriostatic water isn't universal. A few specialty peptides have documented incompatibility with benzyl alcohol, and some GLP-1 analogs can show subtle aggregation at the preservative concentration over longer timelines.
For those, preservative-free sterile water is the cleaner default, traded against losing the 28-day window. Check the peptide manufacturer's reconstitution documentation where you have it. The default works for most peptides, not all.
What does bacteriostatic water cost in 2026?
Bacteriostatic water costs $5–$15 for the standard 30 mL vial, $3–$8 for 10 mL and $10–$20 for 50 mL. It's a utility product: production is cheap, benzyl alcohol costs pennies, and the regulatory framework is settled.
- 30 mL vial: $5–$15 per vial. The standard size; covers many peptide reconstitutions per bottle.
- Multi-pack tiers: 10–25% off per vial for 3-pack or 6-pack orders.
- 10 mL vial: $3–$8 per vial. Usually worse per-mL than the 30 mL.
- 50 mL vial: $10–$20 per vial. Specialty size from some compounding pharmacies.
Above $20 per 30 mL is usually retail markup, or a specialty preparation such as preservative-free, glass ampule or certified compounding grade. Below $5 deserves a second look. The floor reflects regulatory and packaging costs, and prices under it often signal a different product.
For context, a 10 mg BPC-157 reference vial typically runs $80–$150. Bacteriostatic water at 5–10% of peptide cost is a minor line item. Optimizing below the floor is counterproductive. Correct identity is the priority.
Is bacteriostatic water legal to buy?
Yes, easily. It's an FDA-recognized pharmaceutical preparation with an established USP monograph. It carries no controlled-substance scheduling, no 503A category designation, and no WADA Prohibited List status.
The label distinction decides which channel sells it. “Bacteriostatic Water for Injection, USP” is technically a drug product, so compounding pharmacies and licensed pharmaceutical distributors sell that version. The same chemical under research-use-only labeling lives at research-supply distributors. Both are legal, and both contain the same substance.
What are the red flags when buying bacteriostatic water?
Seven bacteriostatic water warning signs we’d skip:
- Label says “sterile water for injection.” No preservative, single-use only. Same cost, identical look, completely different product.
- Label says “0.9% sodium chloride”, which is saline. No preservative. The salt content can also promote aggregation in some peptides. The “0.9%” matches; the active ingredient doesn’t.
- Preservative isn’t benzyl alcohol. Methylparaben, propylparaben, and chlorobutanol-preserved products exist. None are the literature standard.
- No in-use stability claim. A vendor that won’t state the 28-day window is signaling something about their preservative dose.
- Marketing for human use or dosing. Bacteriostatic water itself carries no special restriction, but a vendor who pairs it with human dosing instructions is operating outside research channels and is at higher regulatory enforcement risk.
- Pricing below $3 per 30 mL. Under the regulatory floor usually means it’s a different product under a similar name.
- Glass ampule packaging. Ampules are single-use packaging for preservative-free preparations. Bacteriostatic water ships in multi-dose vials because the preservative is what enables multi-dose use.
Bacteriostatic Water
USP-grade bacteriostatic water for injection · 10 mL multi-dose vial with 0.9% benzyl alcohol preservative. One bottle supports reconstitution of many lyophilized peptide reference compounds. Multi-pack tiers available for parallel research workflows.
Frequently asked questions
What is bacteriostatic water?
Sterile water with 0.9% benzyl alcohol added as a preservative. The benzyl alcohol stops bacteria replicating after first puncture, which supports a 28-day in-use window under refrigerated storage. Without that preservative, an opened vial is single-use only.
How is it different from saline?
Bacteriostatic water is sterile water plus 0.9% benzyl alcohol, a microbial preservative. Normal saline is sterile water plus 0.9% sodium chloride, salt that makes the solution isotonic. They aren't interchangeable. Bac water supports a 28-day in-use window. Saline is single-use, and its ionic strength can promote aggregation in some peptide classes.
How long does a reconstituted peptide vial remain viable?
The standard convention is 28 days at 2–8°C, accessed with sterile technique, with the vial inspected before each use. It's the same convention used for insulin and a wide range of benzyl-alcohol-preserved injectables.
The 28-day clock starts on the reconstitution date, not the date the bac water vial was first opened. Individual peptides may have shorter or longer documented stability, and the manufacturer's data is authoritative where you have it.
Is bacteriostatic water legal to source?
Yes. It's an FDA-recognized pharmaceutical preparation sold legally through compounding pharmacies, online research suppliers, and lab chemical distributors. It carries no scheduling and no 503A category restriction. The label must read “Bacteriostatic Water for Injection, USP” with 0.9% benzyl alcohol stated explicitly.
Can sterile water be used instead?
Sterile water for injection is the chemically cleanest diluent available. No preservative, no salt, just sterile water. It's also single-use once opened, because there's no antimicrobial protection after first puncture. We'd reach for it only when a specific peptide has documented benzyl alcohol incompatibility.
What to know now
- Pharmacies, compounding pharmacies, research suppliers and lab distributors all sell it. Four open routes, one substance.
- Label has to read “Bacteriostatic Water for Injection, USP” with 0.9% benzyl alcohol stated. Other labels mean different products.
- $5–$15 per 30 mL vial. A utility product priced well below the peptides it reconstitutes.
- 28-day in-use window at 2–8°C. Same convention as human insulin.
- USP-grade is the regulatory baseline. Non-USP grades may meet other standards but aren’t the literature default.
- 30 mL multi-dose vial is the standard size. One bottle covers many reconstitutions.
- Optimize for identity, not price. Below-floor pricing usually signals a different product.
What we’re watching
One trend to track is the pharmaceutical industry's shift toward preservative-free single-dose prefilled syringes for some specialty injectables. That's driven by the benzyl alcohol caution in neonates, the “gasping syndrome” first described in the 1980s, and by a broader move toward fewer in-vial additives.
For multi-dose lyophilized peptide reconstitution, the 28-day window is the operational reason the preservative exists. So bacteriostatic water stays the practical default. We're also watching USP-NF monograph updates, because any change to the 28-day convention would propagate across the whole reconstitution literature.
References
- U.S. Food and Drug Administration. (2018). Bacteriostatic Water for Injection, USP — approved label (Hospira/Pfizer, NDA 018632). https://www.accessdata.fda.gov/drugsatfda_docs/label/2018/018632s044lbl.pdf
- United States Pharmacopeial Convention. (2026). Bacteriostatic Water for Injection, USP — monograph in current USP-NF. https://www.usp.org/usp-nf
- United States Pharmacopeial Convention. USP General Chapter <797> — Pharmaceutical Compounding: Sterile Preparations. https://www.usp.org/compounding/general-chapter-797
- American Society of Health-System Pharmacists. Handbook on Injectable Drugs — benzyl alcohol preservative compatibility and stability data. https://www.ashp.org/products-and-services/database-tools/handbook-on-injectable-drugs
- Gershanik, J., Boecler, B., Ensley, H., McCloskey, S., & George, W. (1982). The gasping syndrome and benzyl alcohol poisoning. New England Journal of Medicine, 307(22), 1384–1388. https://doi.org/10.1056/NEJM198211253072206
- U.S. Food and Drug Administration. Insanitary Conditions at Compounding Facilities — Guidance for Industry. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/insanitary-conditions-compounding-facilities-guidance-industry