Green tea can go bad when improperly stored or stored for excessive periods of time. Signs of spoilage in tea include a loss of aroma, signifying the evaporation of the natural oils that give tea its flavor. However, these are quality issues and do not affect the safety of tea.
Green tea can typically be stored for six to 12 months. To extend storage time, green tea can be stored in the freezer for one to two years. Green tea should be stored in a tightly closed container to prevent contamination and moisture from entering. Once brewed, green tea should be consumed within four to six hours.