what happens if you use bac water after 28 days for Peptides: Doctor Explains and Where to Buy Question about BAC water :

Because it contains no bacteriostat to inhibit microbial growth, it cannot be stored for reuse once opened its meant to be used promptly and one-time only under strict aseptic conditions

NHS guidance emphasises that most people should be able to obtain adequate B12 through a balanced diet containing animal products

Cyanocobalamin (Vitamin B12)..............5000 mcg Benzyl Alcohol (preservative).................1.0% v/v Sodium Chloride.................................0.22% w/v Ammonium Sulfate...............................0.1% w/v Citric Acid..........................................0.01% w/v Sodium Citrate..................................0.008% w/v Inject subcutaneously or intramuscularly

Doctors arent overly concerned about this

For daily-use peptide protocols that span days or weeks, bacteriostatic water isnt just more convenient, its meaningfully safer