Refrigerated after opening, bacteriostatic water is generally usable for about 28 days. Cold storage helps preserve it through that multi-use window. Unopened, it keeps until its printed expiration whether refrigerated or not.
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