# Common questions, answered plainly

Start with the short answer. Stop when the question belongs to the medicine's label or to a pharmacist.

## The basics

### What is bacteriostatic water?

It is sterile water with benzyl alcohol added as a preservative. The preservative helps limit bacterial growth in a bottle made for more than one withdrawal.

### What is it used for?

It is a diluent for injectable medicines. It can dissolve a dry medicine or thin a liquid one when that medicine's instructions call for it.

### Is “bac water” different?

No. It is a common short name. The short name says nothing about whether a bottle is approved.

## Comparisons

### Is it the same as sterile water?

No. Sterile water has no preservative and comes in a single-dose container. Bacteriostatic water contains a preservative and comes in a multiple-dose container.

### Is it the same as saline?

No. Saline contains salt and is about as concentrated as blood. Bacteriostatic water is not a fluid replacement.

### Is “reconstitution solution” the same thing?

Not reliably. It is not an approved US medicine name. The phrase alone does not reveal the contents or approval status.

## Storage

### Does the bottle go in a refrigerator?

No. Its label calls for storage at 68°F to 77°F, or 20°C to 25°C. A mixed medicine can have different storage directions.

### How long does an opened bottle last?

CDC guidance says to date an opened multi-dose vial and discard it within 28 days unless the maker gives another date. The water label itself does not print that interval.

### Does it expire?

Yes. The sealed bottle has a printed expiration date. The shorter clock after first entry cannot run past that date.

## Access and approval

### Where does a person get an approved bottle?

A state-licensed pharmacy dispenses the prescription product. It may also come inside the package with the medicine that needs it.

### Is there an over-the-counter version?

No. The approved US product is prescription-only.

### How can a bottle be checked?

Start with the NDC Directory, then match the application in Drugs@FDA and read the label on DailyMed. An NDC number alone does not prove approval.

## Why no mixing amount appears here

The medicine's current label decides the liquid and amount. A pharmacist or prescriber checks it. The answer can change between medicines and even between strengths of the same medicine.

This guide does not give volumes, concentration formulas, syringe conversions, or mixing steps.

## Firm stops

- It is not injected on its own.
- It is not suitable for every injectable medicine.
- It has no approved use by mouth.
- It cannot be made at home by boiling water and adding a preservative.
- It must not be used in newborn babies.

[Read the source trail](https://purebacteriostaticwater.com/source-trail/).