its usually good a couple years..yours doesnt say on the bottle?? and it does not have to be refridgerated.. i always keep mine in the fridge anyway tho.
Bacteriostatic Water for Injection, USP is supplied in a multiple-dose 30 mL plastic fliptop vial (List No. 3977). Store at controlled room temperature 15° to 30°C (59° to 86°F).