Bacteriostatic water vial sizes: 3 mL vs 10 mL vs 30 mL
Pick the smallest vial you will finish within its post-puncture use window. CDC, citing USP <797>, says an opened multi-use vial should be dated and discarded within 28 days unless the manufacturer states another date. The FDA-labeled prescription product is listed in 30 mL vials and as a 20 mL fill in a 30 mL vial. Research-use 3 mL and 10 mL vials suit lower usage, and 10-packs bring the cost per mL down.
What sizes does bacteriostatic water come in?
The FDA-labeled prescription product's current DailyMed label lists two presentations: a 30 mL plastic multiple-withdrawal vial with 0.9% benzyl alcohol, and a 20 mL fill in a 30 mL glass vial with 1.1% benzyl alcohol, each sold in trays of 25 [1]. A repackager's DailyMed listing for the same product also shows a 30 mL vial with 0.9% benzyl alcohol [2]. We found no 3 mL or 10 mL fill among the FDA-labeled listings we checked on DailyMed.
Products sold for laboratory and research use come in smaller fills. Batch currently offers 3 mL and 10 mL vials, as a single 10 mL vial or as 10-packs of either size. Batch doesn't sell a 30 mL vial at the moment.
Supply affects which sizes you can get. As of October 24, 2026, ASHP's shortage bulletin for the prescription product lists the 30 mL vial as affected by manufacturing delays and available in limited supply [3]. For the full picture, see where to buy bacteriostatic water.
Is fill volume the same as vial size?
Not always. The label's 20 mL presentation is a 20 mL fill in a 30 mL glass vial [1], so the container is larger than the liquid it holds. The empty space above the liquid is the headspace. When you compare listings, look for the stated fill volume (the mL of solution you get), not the container size or a photo. If a listing only says "30 mL vial", ask whether that's the fill or the container.
How do you choose between 3 mL, 10 mL and 30 mL?
Work backwards from two numbers: how much you withdraw from one vial in a typical work session, and how long you can keep a vial once it's been punctured. CDC's guidance, citing USP General Chapter 797, says an opened multi-use vial should be dated and discarded within 28 days unless the manufacturer states another date, and that this date should never be later than the manufacturer's original expiration date [4]. The FDA-labeled product's label also says to use the solution only if it's clear and the seal is intact [1]. Research products should follow their own labeling, but the 28-day window is a sensible planning limit for any vial that's punctured repeatedly.
- Estimate your weekly volume per vial, for example 1 mL across several withdrawals.
- Multiply by four to get roughly 28 days. At 1 mL a week, you use about 4 mL before the window closes.
- Choose the smallest fill that covers that volume with a little margin. At 4 mL, a 10 mL vial leaves about 6 mL unused, and a 30 mL vial leaves about 26 mL.
- If you use several mL a day, a larger fill can make sense, as long as you'll finish it inside the window.
Small fills cost a little more per mL, but they waste less when usage is low or irregular. They also limit how many withdrawals any one vial goes through. In a shared lab, separate vials for separate projects make dating and lot tracking simpler. For shelf-life detail, see bacteriostatic water shelf life and storage.
| Fill volume | Volume used per week to finish in ~28 days | Typical fit |
|---|---|---|
| 3 mL | About 0.75 mL | Occasional or single-project use; minimal waste |
| 10 mL | About 2.5 mL | Regular weekly bench use |
| 20 mL | About 5 mL | Heavier use |
| 30 mL | About 7.5 mL | High-volume, steady use |
What does bac water cost per mL in a 10 pack?
Here is the per-mL math for Batch's current list prices, worked out from the catalog. Subscribe & Save takes 15% off each delivery. A 10-pack of 10 mL vials costs about a third less per mL than a single 10 mL vial.
| Option | Total volume | Price | Per vial | Per mL | Per mL with Subscribe & Save |
|---|---|---|---|---|---|
| 10 mL, single vial | 10 mL | $11.99 | $11.99 | $1.20 | $1.02 |
| 3 mL × 10 | 30 mL | $29.99 | $3.00 | $1.00 | $0.85 |
| 10 mL × 10 | 100 mL | $79.99 | $8.00 | $0.80 | $0.68 |
Cost per mL only counts the liquid you actually use. If a 10 mL vial reaches its 28-day mark with 6 mL left, you've paid for 10 mL and used 4 [4]. In that case a 3 mL 10-pack may cost less per mL used, even though its list price per mL is higher. One-time orders of $50.00 or more ship free, so the 10 mL 10-pack ships free on its own. Compare Batch 10 mL vials and 10-packs, and see how Batch tests every batch for how to request a lot's Certificate of Analysis.
Key takeaways
- The FDA-labeled prescription product is listed in 30 mL vials and as a 20 mL fill in a 30 mL vial [1, 2].
- Fill volume and container size can differ, so compare the mL of solution, not the vial [1].
- Size a vial so you finish it within 28 days of the first puncture, unless the labeling gives another date [4].
- Batch currently offers 3 mL and 10 mL. A 10-pack of 10 mL vials works out to $0.80 per mL at list price.
Frequently asked questions
Is a 30 mL vial better value than a 10 mL vial?
Only if you use it up. A larger fill usually costs less per mL, but anything left after the 28-day post-puncture window is wasted [4].
Does Batch sell 30 mL bacteriostatic water?
Not currently. Batch offers a single 10 mL vial, a 10-pack of 3 mL vials and a 10-pack of 10 mL vials.
Why is a 20 mL fill sold in a 30 mL vial?
The label lists that presentation as a 20 mL fill in a 30 mL glass vial [1], so the vial holds less liquid than its capacity. Always check the stated fill volume.
Does the 28-day window start when the vial ships?
No. An unopened vial is good until the manufacturer's expiration date. The 28-day window starts at the first puncture and can't run past that expiration date [4].
For laboratory and research use only. Not for human or veterinary use. Not intended to diagnose, treat, cure, or prevent any disease.
Sources
- Bacteriostatic Water for Injection, USP — label (Hospira, Inc.) — DailyMed, U.S. National Library of Medicine. Accessed October 24, 2026.
- Bacteriostatic Water for Injection, USP — label (ProPharma Distribution) — DailyMed, U.S. National Library of Medicine. Accessed October 24, 2026.
- Drug Shortage Detail: Bacteriostatic Water for Injection — American Society of Health-System Pharmacists (ASHP). Accessed October 24, 2026.
- Preventing Unsafe Injection Practices (multi-dose vials) — Centers for Disease Control and Prevention. Accessed October 24, 2026.