Bacteriostatic water (BAC) is sterile water but gets its name from the addition in containing 0.9% benzyl alcohol that is used to dilute or dissolve medications so they can be safely injected in patients.

Bacteriostatic water is usually available in 10, 20 and 30ml bottles and should always be sealed before first use.

The silicone bottle stopper can be re-entered multiple times like when using a peptide vial and the benzyl alcohol suppresses or stops the growth of most potentially contaminating. Bacteriostatic water is acidic with an average PH level of 5.7.

The PH level in Bacteriostatic water is regarded better than Sterile water for injection for use with peptides.

Bacteriostatic water should be stored out of direct sunlight, preferably in a dark place at temperatures no higher than 20 degrees Celsius it can also be keep in the fridge. Once opened it should be used within 3 months any time after that should be discarded as the effectiveness of the benzyl alcohol will start to lose its potency.

I would add here that with fragile peptides I would try to make sure the water and the peptide is close to each other’s temperature when reconstituting to safeguard the purity of the peptide.

Sterile water for injection even though safe for the body it is only to be used for single use. This is why bacteriostatic water not only helps to dissolve and hold the peptide better but also is ideal for peptides which vials are used more than once.