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Bac Water (Bacteriostatic Water), 30 mL

Sterile water with 0.9% benzyl alcohol added, which keeps an opened vial usable for about 28 days instead of hours. "Bac water" is just the everyday short name for it — same product.

Last edited 2026-09-28 · written by PepPrep

30 mL
Preserved
~28 days open

What it’s for

The water for any vial you will draw from more than once: its 0.9% benzyl alcohol is what lets an opened bottle be used for about 28 days.

What to check in the listing

Check the label says 0.9% benzyl alcohol and the cap is sealed. In the US the pharmacy name you'll see is Hospira; in Canada, the UK and Australia it's mostly sold as “reconstitution solution” — the same thing, so go by the percentage, not the name. 30 mL is only better value if you'll use it inside the 28 days.

At a glance

TypeMixing liquid

LiquidBacteriostatic waterLiquid is what the bottle holds. Bacteriostatic water has a preservative and keeps 28 days once opened; sterile water and saline have none and are single-use. Glossary

PreservativeYesPreservative says whether it carries one: 0.9% benzyl alcohol stops bacteria multiplying in an opened bottle, and it is what makes a multi-dose bottle possible. Glossary

Volume30 mL

Single-useNo

Once opened28 daysOnce opened is how long the bottle is considered good after the first needle goes through the stopper.

Used forMixing vialsUsed for lists the situations this product is for; the decision tool and the Finder match on these.

PriceBudgetPrice tier is the rough position within its category, not a live price: budget is the cheapest sensible option, premium costs more for a reason the page explains.

TravelCarry-on friendlyTravel says whether it is practical to fly with: carry-on means it goes through security without fuss.

SterileYesSterile means individually sealed and sterile until opened; anything that touches the inside of a vial or your skin should be.

Pack1Pack is how many come in the listing this site links to; it is shown only where every store's listing gives the same count. Check it against the listing, since photos often show ten and ship one.

ReusableNo

Specifications above were recorded from the Amazon listing on 2026-09-03. Listings change hands: open the listing for its current description, price and availability.

If you're not sure which water a vial needs, or how long an opened bottle lasts, read How long does bac water last once opened? first. The side-by-side bacteriostatic water vs sterile water comparison covers the other half of the choice.

Category: Mixing & Water
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Bac Water (Bacteriostatic Water), 30 mL

What it’s for

What to check in the listing

At a glance

Others in Mixing & Water

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