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What is bacteriostatic water?
Sterile water with 0.9% benzyl alcohol added. The alcohol stops bacteria multiplying after the seal is first punctured, which is why an opened bottle is generally treated as good for about 28 days rather than one sitting. Full comparison → Full explanation →
Why it matters when you shop
Sterile water with 0.9% benzyl alcohol added, which stops bacteria multiplying in an opened vial. That preservative is what makes a multi-dose vial possible: about 28 days after the first puncture. It is not the same as sterile water (no preservative, single use) or saline (salt water, for nasal preparations).
What to look for on the listing
- "Bacteriostatic" and "0.9% benzyl alcohol" on the label, not just "sterile".
- Vial size: 30 mL is standard; 10 mL for occasional use.
- A sealed cap and a printed expiry; never a bottle sold as "for irrigation".
Go deeper
- Guide: Bac water vs. sterile water (and which to buy)
- Comparison: Bac Water Vs Sterile Water
- Tool: Product Finder for this category
- All terms: the glossary
Products where this number appears
Reviewed 2026-09-03. Definitions describe equipment, not treatment. Affiliate links open your own country's Amazon store; your price is the same.