Bacteriostatic Water calculator
Sterile water with 0.9% benzyl alcohol, used to dissolve and store injectable medications. The standard reconstitution liquid.
Also known as: BAC water, Bacteriostatic water for injection, BW
FDA status — not an approved drug Bacteriostatic water for injection is an FDA-regulated sterile diluent. It is not a drug itself — it is used to dissolve and store other injectable medications.
This draw does not fit the selected syringe.100000 units exceeds the 100-unit barrel. Choose a larger syringe, use less bacteriostatic water, or split the dose.
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What Bacteriostatic Water is
Bacteriostatic water is sterile water containing 0.9% benzyl alcohol as a preservative. It is the standard liquid used to dissolve and store injectable peptides and medications. The benzyl alcohol inhibits bacterial growth, allowing a reconstituted vial to be used over multiple withdrawals. It is a diluent, not a drug.
Research depth: 5/5 The standard, well-characterized reconstitution diluent for injectable medications. Human trials: Regulated diluent. This measures how much has been studied — counting animal and laboratory work — not whether it works for you.
How Bacteriostatic Water works
The benzyl alcohol preservative disrupts bacterial cell membranes, preventing contamination from growing in a multi-dose vial. This is what distinguishes it from plain sterile water, which has no preservative and must be used once. The water itself is simply the vehicle that carries the dissolved medication.
Bacteriostatic Water side effects
Commonly reported
- Not an active ingredient — no therapeutic effect
- Benzyl alcohol can cause local irritation in sensitive individuals
Serious — seek medical care
- Not for use in newborns — benzyl alcohol is toxic to infants
- Contamination risk if multi-dose technique is poor
- Not a medication — it is a reconstitution vehicle
This list is not exhaustive. Report anything unexpected to the clinician who prescribed it. If you have severe abdominal pain, trouble breathing, or signs of an allergic reaction, seek care the same day. See also our guide to peptide side effects by class.
A worked example
A 30 mg vial reconstituted with 30 mL of bacteriostatic water gives 1 mg/mL. A 1000000 mcg dose is then 1000 mL — about 100000 units on a 100-unit insulin syringe, giving roughly 0 doses per vial before accounting for residual volume left in the vial and syringe.
Prefer paper? Download the printable Bacteriostatic Water dosing chart (PDF) — every vial size and water volume in syringe units, with the same review byline as this page. All charts →
Commonly cited dose range
Figures circulating for Bacteriostatic Water run from 1000000 mcg to 1000000 mcg. This is a solvent, not an active ingredient — it has no dose. It is the liquid used to reconstitute peptides. Figures shown reflect that it is a reconstitution liquid, not a dosed compound.
Read this as reference information, not instruction. These numbers describe what is commonly discussed, not what is right for any individual. Dose, frequency, and whether to use Bacteriostatic Water at all are decisions for a licensed clinician who knows your history.
Common questions
What is bacteriostatic water used for?
It is the standard liquid for reconstituting injectable peptides and medications. The 0.9% benzyl alcohol inhibits bacterial growth, allowing a vial to be used multiple times over its storage life.
How is bacteriostatic water different from sterile water?
Sterile water has no preservative, so it is single-use. Bacteriostatic water contains benzyl alcohol, which suppresses bacterial growth and permits multiple withdrawals from the same vial.