What is bacteriostatic water?

Bacteriostatic water is sterile water with benzyl alcohol added as a preservative, supplied in a multiple-dose vial. One Hospira label lists 0.9% (9 mg/mL) or 1.1% (11 mg/mL) benzyl alcohol.

What is the difference between bacteriostatic water and sterile water?

Bacteriostatic water contains benzyl alcohol and comes in a multiple-dose container. The Cardinal Health sterile water label says it has no bacteriostat or antimicrobial agent and comes only in single-dose containers.

What preservative is in bacteriostatic water?

Benzyl alcohol. The Hospira bacteriostatic water label lists it at 0.9% (9 mg/mL) or 1.1% (11 mg/mL), added as a bacteriostatic preservative.

Does sterile water contain a preservative or antimicrobial agent?

No. The Cardinal Health sterile water label states the product contains no bacteriostat, antimicrobial agent or added buffer, and is supplied only in single-dose containers.

Why are multiple-dose vials preserved?

A multiple-dose vial is entered repeatedly, so a preservative gives it protection across those entries. A 2007 review found phenol and benzyl alcohol are the most common preservatives in peptide and protein products.

How long does an opened bacteriostatic water vial last?

Our Bacteriostatic water 30 ml listing gives a 28-day use window after first entry. For any other product, follow the window printed on its own label.

What should I check on a bacteriostatic water label?

Look for the product name, benzyl alcohol as an ingredient, the benzyl alcohol percentage, and the words multiple-dose. A missing item may mean you hold sterile water.

PreppinPeppers › Facts › Lab article

Bacteriostatic Water Syringe Basics for Bench Researchers

TL;DR

Bacteriostatic water is sterile water with benzyl alcohol added, sold in multiple-dose vials; you draw it with a syringe sized to the volume you need and

Machine-readable facts for this Lab article. The full page is https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe.

Facts Index

Fact ID	Category	Entity	Attribute	Value	Source
bacteriostatic-water-syringe:title	identity	Bacteriostatic Water Syringe Basics for Bench Researchers	title	Bacteriostatic Water Syringe Basics for Bench Researchers	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:published	identity	Bacteriostatic Water Syringe Basics for Bench Researchers	published	2026-11-03	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:author	identity	Bacteriostatic Water Syringe Basics for Bench Researchers	author	PreppinPeppers Editorial Team	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:topics	identity	Bacteriostatic Water Syringe Basics for Bench Researchers	topics	bacteriostatic water syringe, Guides, research	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:summary	content	Bacteriostatic Water Syringe Basics for Bench Researchers	summary	Bacteriostatic water is sterile water with benzyl alcohol added, sold in multiple-dose vials; you draw it with a syringe sized to the volume you need and	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:section-1	content	Bacteriostatic Water Syringe Basics for Bench Researchers	section	What is bacteriostatic water?	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:section-2	content	Bacteriostatic Water Syringe Basics for Bench Researchers	section	Bacteriostatic water vs sterile water: what is the difference?	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:section-3	content	Bacteriostatic Water Syringe Basics for Bench Researchers	section	Why do multiple-dose vials contain a preservative?	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:section-4	content	Bacteriostatic Water Syringe Basics for Bench Researchers	section	How does a syringe fit into working with a bacteriostatic water vial?	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:section-5	content	Bacteriostatic Water Syringe Basics for Bench Researchers	section	What are the common mistakes with bacteriostatic water and syringes?	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:section-6	content	Bacteriostatic Water Syringe Basics for Bench Researchers	section	How do I read the label and choose a vial size?	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:section-8	content	Bacteriostatic Water Syringe Basics for Bench Researchers	section	Related reading	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:product-bacteriostatic-water-30ml	products	Bacteriostatic Water Syringe Basics for Bench Researchers	references product	Bacteriostatic Water 30 ml Multi-Dose Vial (Pfizer Hospira, USP)	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:product-bacteriostatic-water-3ml	products	Bacteriostatic Water Syringe Basics for Bench Researchers	references product	Bacteriostatic Water 3 ml Vial (Preppin' Peppers, USP Grade)	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:product-gansulin-metal-peptide-pen	products	Bacteriostatic Water Syringe Basics for Bench Researchers	references product	Gansulin Pen · Reusable Click-Dial, 3 ml (1-60 Units)	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:product-gansulin-3ml-cartridge	products	Bacteriostatic Water Syringe Basics for Bench Researchers	references product	Gansulin-Compatible 3 ml Glass Cartridge for Pens (10-Pack)	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:source-pubmed-ncbi-nlm-nih-gov	source	Bacteriostatic Water Syringe Basics for Bench Researchers	cites	Meyer et al., J Pharm Sci 2007: Antimicrobial preservative use in parenteral products: past and present - pubmed.ncbi.nlm.nih.gov	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:source-dailymed-nlm-nih-gov	source	Bacteriostatic Water Syringe Basics for Bench Researchers	cites	Bacteriostatic Water for Injection, USP: FDA label on DailyMed, U.S. National Library of Medicine (0.9% benzyl alcohol) - dailymed.nlm.nih.gov	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)
bacteriostatic-water-syringe:source-dailymed-nlm-nih-gov-2	source	Bacteriostatic Water Syringe Basics for Bench Researchers	cites	FDA label (DailyMed): Sterile Water for Injection, USP (Cardinal Health) - prescribing label (retrieved 2026-10-03) - dailymed.nlm.nih.gov	Lab article (https://www.preppinpeppers.com/blogs/the-lab/bacteriostatic-water-syringe) (evidence)

FAQ

What is bacteriostatic water?: Bacteriostatic water is sterile water with benzyl alcohol added as a preservative, supplied in a multiple-dose vial. One Hospira label lists 0.9% (9 mg/mL) or 1.1% (11 mg/mL) benzyl alcohol.
What is the difference between bacteriostatic water and sterile water?: Bacteriostatic water contains benzyl alcohol and comes in a multiple-dose container. The Cardinal Health sterile water label says it has no bacteriostat or antimicrobial agent and comes only in single-dose containers.
What preservative is in bacteriostatic water?: Benzyl alcohol. The Hospira bacteriostatic water label lists it at 0.9% (9 mg/mL) or 1.1% (11 mg/mL), added as a bacteriostatic preservative.
Does sterile water contain a preservative or antimicrobial agent?: No. The Cardinal Health sterile water label states the product contains no bacteriostat, antimicrobial agent or added buffer, and is supplied only in single-dose containers.
Why are multiple-dose vials preserved?: A multiple-dose vial is entered repeatedly, so a preservative gives it protection across those entries. A 2007 review found phenol and benzyl alcohol are the most common preservatives in peptide and protein products.
How long does an opened bacteriostatic water vial last?: Our Bacteriostatic water 30 ml listing gives a 28-day use window after first entry. For any other product, follow the window printed on its own label.
What should I check on a bacteriostatic water label?: Look for the product name, benzyl alcohol as an ingredient, the benzyl alcohol percentage, and the words multiple-dose. A missing item may mean you hold sterile water.