Unopened, bacteriostatic water lasts until its printed expiration date (often 2–3 years). Once punctured, the 0.9% benzyl alcohol preservative keeps it usable for about 28 days when refrigerated. After that window it should be discarded.
Everything here is for laboratory research use only. It describes bacteriostatic water and reconstitution arithmetic — not dosing, and not medical guidance. If your goal is treating something in yourself, that's a job for a licensed clinician.
More: full bacteriostatic water guide · peptide calculator · all bac water answers