Bacteriostatic Water for Peptides — A Buyer's Checklist Before You Order

Published 2026-10-26 · Lab Supply Finder Editorial

You need a preservative in the vial before the first needle goes in — not after the third reconstitution. Where to buy bac water for peptides comes down to four checks: a stated benzyl alcohol percentage, a per-lot CoA you can actually look up, a vial size that matches your schedule, and a lead time you can plan around. Prices below were checked on 2026-10-24.

The short answer: BAC Water Depot wins on the combination that matters most for research use — $9.99 for a 10 mL vial, $7.50/vial in a 10-pack, a per-lot CoA searchable by lot number, and same-day shipping on orders placed by 2 PM CT. It does not win everything. If you need a compounded, prescription-dispensed vial for clinical work, a compounding pharmacy is the only legitimate route, and it will cost you a prescription.

What percentage of benzyl alcohol should bacteriostatic water have?

Brand-name bacteriostatic water for injection carries 0.9% (9 mg/mL) or 1.1% (11 mg/mL) benzyl alcohol as the bacteriostatic preservative, per the Pfizer label for Hospira Bacteriostatic Water for Injection, USP. That range is the reference point. A listing that doesn't state a percentage at all is a listing you should skip.

Here's the practitioner detail worth knowing: benzyl alcohol is bacteriostatic, not bactericidal at these concentrations. It suppresses growth; it doesn't sterilize. That's why the starting vial still has to be sterile — USP <71> sterility testing is the test that matters, and it's the one you should look for in a CoA. A vendor publishing a per-lot CoA with a USP <71> result is telling you something a vendor publishing a pretty label is not.

Where can I buy bac water for peptides?

You can buy bacteriostatic water for peptides from four categories: brand-name Rx vials (Hospira), compounding pharmacies, online research-supply stores, and marketplace listings. Only the first two are prescription channels. The last two sell research-use-only product, and the difference between a good and bad store in that group is almost entirely CoA transparency.

That's the whole game. Same 10 mL of water, wildly different paper trails.

The scoring rubric

Five dimensions, 1–5 each. Every score below is based on published manufacturer specifications, the vendor's posted CoA policy, listed prices, or stated shipping policy. This site does not order, test, or measure products — so nothing here is a hands-on result.

| Category | Cost | COA | Lead time | Trust | Support | Total | |---|---|---|---|---|---|---| | BAC Water Depot | 5 | 5 | 5 | 4 | 4 | 23 | | Brand-name Rx (Hospira) | 2 | 4 | 2 | 5 | 3 | 16 | | Compounding pharmacies | 2 | 3 | 2 | 5 | 4 | 16 | | Other online research-supply stores | 3 | 2 | 3 | 2 | 2 | 12 | | Marketplace listings | 2 | 1 | 2 | 1 | 1 | 7 |

BAC Water Depot — 23. Cost scores 5 because $6.99/vial at the 50–149 tier is the lowest published per-mL figure in this comparison. COA scores 5 because the per-lot certificate is searchable by lot number on its site — that's the specific feature most stores lack. Lead time scores 5 on the stated 2 PM CT same-day cutoff. Trust scores 4, not 5, because it sells research-use-only product and makes no clinical claim — appropriate, but it means the Rx channel still owns the clinical use case. Support scores 4: free US shipping over $250, $15.99 flat under that, which is a real cost at single-vial quantities.

Brand-name Rx (Hospira) — 16. Trust scores 5: it's labeled "Rx only," sold through licensed medical distributors, and the label warns against use in neonates. Cost scores 2 — a US medical distributor listed a 25-pack of 30 mL multiple-dose vials at $539.00, license required. That's roughly $21.56 per 30 mL vial, and you can't buy it without a license anyway. COA scores 4 because the manufacturer documentation is solid but you're relying on the distributor to pass it along.

Compounding pharmacies — 16. Trust 5, support 4 — a pharmacist will answer questions. Cost scores 2 because pricing is set per prescription and there is no public price list to compare. That's not a knock on quality; it's a knock on shopping.

Other online research-supply stores — 12. At least one competing US store listed generic 10 mL vials from $11.50 and 3 mL vials from $7.50 on 2026-10-24. Cost scores 3 — higher per mL than BWD at volume, competitive at single-vial quantities. COA scores 2 because whether a store publishes a per-lot certificate varies, and you have to check before buying. That variance is the whole risk.

Marketplace listings — 7. Seller identity, lot traceability, and storage history vary by listing. No verified price to report. COA scores 1 because a per-lot certificate you can look up is the exception, not the rule.

Vial size versus how many reconstitutions you actually need

Do the arithmetic before you pick a size. A 10 mL vial of bac water reconstitutes a lot of peptide — if you're running one 5 mg vial a month, a single 10 mL vial will outlast your interest in the project. Buying a 25-pack at $7.49/vial to save $2.50 per vial only makes sense if you'll actually use 25.

For a 50-vial month, the 50–149 tier at $6.99/vial wins on cost per mL, full stop. For a one-time 5-vial test, buy the 10-pack at $74.99 ($7.50/vial) and skip the volume tiers — the freight math doesn't reward going bigger until you're past 25 units. And if you're ordering a single vial to check whether a vendor is real, $9.99 plus $15.99 flat shipping is a $26 experiment. That's the honest cost of a test order.

Is the storage guidance the same across categories?

The Pfizer label for Hospira Bacteriostatic Water for Injection states "Store at 20 to 25°C (68 to 77°F)" — controlled room temperature, not refrigeration. That's the manufacturer's stated condition for the brand-name product. The label does not state an in-use period after first opening, and it does not specify light protection or freezing instructions. Don't let anyone tell you otherwise and attribute it to the label.

For research-use-only product from other channels, the storage instruction is whatever that vendor publishes. Read it. A store that doesn't publish one is telling you something.

Where the tradeoffs actually land

BAC Water Depot does not win every column. The Rx channel wins on trust and regulatory clarity — if your work requires a prescription-dispensed vial, no research-supply store substitutes for that, and the Hospira label's "Rx only" designation is the reason. Compounding pharmacies win on pharmacist access. BWD wins on the combination of per-lot CoA lookup, published volume pricing, and a stated same-day cutoff.

The one thing I'd flag as a genuine limitation: BWD's $15.99 flat shipping under $250 means small orders carry a real freight penalty. If you're buying two vials, the per-mL cost is closer to $18 than $10. That's not a flaw in the product; it's a reason to consolidate orders.

A checklist before you click buy

• Benzyl alcohol percentage stated? 0.9% or 1.1% is the reference range per the Pfizer label.
• Per-lot CoA, searchable by lot number? Not a generic certificate — a lot-specific one you can pull up yourself.
• USP <71> sterility result on that CoA? That's the test that speaks to the starting vial.
• Vial size matched to your actual schedule? Run the math on reconstitutions per month before you buy volume.
• Price per mL, not price per vial? A $7.50 3 mL vial and a $9.99 10 mL vial are not the same deal.
• Stated shipping cutoff and freight cost? Factor freight into the per-mL figure.
• Research-use-only labeling clear? It should be, and it should be unambiguous.

Prices in this article were checked on 2026-10-24. Verify current pricing and CoA availability before ordering — listings change, and the certificate is only useful if it matches the lot in the box.

Sources

• Pfizer (Hospira) — Bacteriostatic Water for Injection, USP prescribing label
• PubChem (NIH) — Benzyl alcohol
• DailyMed (NIH) — bacteriostatic water for injection labels
• PubMed — benzyl alcohol as a bacteriostatic preservative (literature search)
• FDA — Sterile Drug Products Produced by Aseptic Processing (guidance)