Bacteriostatic Water Guide
Bacteriostatic water (BAC water) is the foundation of peptide reconstitution. Containing 0.9% benzyl alcohol as a preservative, it allows reconstituted peptides to be stored for weeks while preventing bacterial growth. Understanding BAC water properties is essential for safe peptide handling.
Key Points
Step-by-Step Guide
Understand BAC Water
Bacteriostatic water is sterile water with 0.9% benzyl alcohol. The preservative inhibits bacterial growth, enabling multi-use vial storage. Available in 10 mL and 30 mL vials from pharmacies and medical suppliers.
Source Quality BAC Water
Purchase from pharmacies, compounding pharmacies, or reputable medical supply vendors. Look for USP-grade with intact seals. Avoid unbranded or suspiciously cheap sources.
Store Properly
Unopened: room temperature, away from light, per expiration date (typically 1-2 years). After first puncture: room temperature or refrigerated, use within 28 days.
Use Correct Technique
Swab the rubber stopper with alcohol before each puncture. Use a new sterile needle each time you draw from the vial. Avoid touching the stopper with fingers.
Know When to Discard
Discard 28 days after first puncture regardless of remaining volume. Discard if the solution appears cloudy, discolored, or contaminated. Discard if past the manufacturer expiration date.
Warnings & Precautions
- !Use within 28 days of first puncture.
- !Benzyl alcohol is contraindicated in neonates—not relevant for adult peptide research.
- !Do not use if seal is broken or solution appears contaminated.
- !Sterile water (without preservative) is NOT a substitute for multi-dose use.
Frequently Asked Questions
What is the difference between BAC water and sterile water?
BAC water contains 0.9% benzyl alcohol preservative; sterile water has no preservative. BAC water allows multi-dose use over weeks. Sterile water must be used within hours as bacteria can grow in it.
Where can I buy bacteriostatic water?
Pharmacies (ask at the counter), compounding pharmacies, Amazon (medical supply sellers), and medical supply websites. Verify USP-grade and intact seals. Typical cost: $5-15 per 30 mL vial.
Can BAC water go bad?
Yes. Unopened vials expire per the manufacturer date (usually 1-2 years). Once punctured, the 28-day limit applies because the benzyl alcohol concentration may decrease with repeated needle punctures and exposure.