BAC Water

BAC water is the shorthand you’ll encounter most often in peptide communities and protocols. It refers specifically to bacteriostatic water — sterile water preserved with 0.9% benzyl alcohol — rather than plain sterile water, saline, or water for injection.

The distinction matters: plain sterile water has no preservative and should not be used for multi-dose vials. BAC water’s preservative property is what makes it safe to draw from the same vial multiple times over 2–4 weeks without contamination risk.