What is BAC water? A plain English explainer
Updated October 29, 2026. General information, not medical advice. This site makes no usage claims.
BAC water is bacteriostatic water: sterile water that contains 0.9% benzyl alcohol, which limits bacterial growth.
- Labs use it as a diluent for materials that need to be dissolved.
BAC water vs other water
| Type | What it is |
|---|---|
| Bacteriostatic water | Sterile water plus 0.9% benzyl alcohol |
| Sterile water | Sterile water with no preservative |
What to ask a vendor
- Is the product sterile and sealed?
- Is there a lot number and expiry?
- What guidance do they provide?
I do not give instructions on preparing or using any compound. Follow the vendor and any qualified professional you work with.
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Common questions
What is BAC water made of?
Sterile water with 0.9% benzyl alcohol as a preservative.
Is BAC water the same as sterile water?
No. Sterile water has no preservative.
Do you explain how to use it?
No. This site makes no usage claims.