Reducing the caffeine from tea is tremendously easy and there is no need to actually buy decaffeinated tea. Simply soak tea leaves in hot water for approximately 45 seconds and then pour the water away. After that add new water and brew that cup of tea the way you want to. Since even 80% of the caffeine is dissolved quickly into water, second brew will have minimal amounts of caffeine, yet sacrificing only relatively little of the aroma or flavor of the divine drink.
Common production method for decaffeinate tea is to use ethylic acetate, which saves only 30% of polyphenols. If you are drinking factory-made decaffeinated tea, make sure that the process is based one natural methods of using water and CO2, which saves 95% of polyphenols.