Bacteriostatic Saline (0.9% Sodium Chloride) vs Bacteriostatic Water: What's the Difference?

• Bacteriostatic saline — bacteriostatic 0.9% sodium chloride — is isotonic salt solution with 0.9% benzyl alcohol as a preservative.
• Bacteriostatic water is preserved water without sodium chloride; the two are different products with different labels.
• Both are supplied as multi-dose diluents, not ready-to-administer medicines.
• Which diluent is compatible with a given medicine is determined by that medicine's product information and a qualified healthcare professional.

Shoppers searching for a preserved diluent in Australia run into two similar-sounding products: bacteriostatic saline — labelled as bacteriostatic 0.9% sodium chloride — and bacteriostatic water. They are related but not interchangeable, and the label on each vial is what defines them. This guide explains what each product is and what to check before buying.

What bacteriostatic saline is

Bacteriostatic sodium chloride 0.9% — often shortened to bacteriostatic saline, BAC saline, BAC sodium chloride or preserved saline — is an isotonic solution of 0.9% sodium chloride in water with 0.9% benzyl alcohol added as a bacteriostatic preservative. It is supplied in multi-dose vials and labelled as a diluent for compatible medicines, set out in the manufacturer product information.

What bacteriostatic water is

Bacteriostatic water for injection — BAC water — is sterile water with the same 0.9% benzyl alcohol preservative but no sodium chloride. It is also a multi-dose diluent. We cover it in detail in What is BAC water? and in our Hospira presentation guide.

The differences at a glance

• Composition — saline contains 0.9% sodium chloride and is isotonic; bacteriostatic water contains no salt and is hypotonic on its own.
• Label — each carries its own manufacturer product information, compatibility notes and warnings; one is not a substitute for the other.
• What they share — both are preserved with 0.9% benzyl alcohol, supplied multi-dose, and are diluents rather than ready-to-administer medicines.

Which one do you need?

That is not a question a retailer can answer for you. The medicine being prepared dictates the compatible diluent; check its supplied product information and ask a qualified healthcare professional. Our role is to supply factory-sealed, manufacturer-labelled presentations so what you receive is exactly what the label says.

Buying either in Australia

Aus BAC Supply dispatches both presentations from Melbourne in original manufacturer packaging:

• Bacteriostatic sodium chloride 0.9% (BAC saline) — preserved isotonic multi-dose diluent.
• Hospira bacteriostatic water (BAC water) — preserved multi-dose diluent, no sodium chloride.

Whichever you buy, apply the same supplier checks we outline in where to buy bacteriostatic water in Australia: intact seal, readable manufacturer label, visible lot and expiry, and a contactable Australian business.