Using water that is too hot will destroy polyphenols and other healthy compounds in tea (and its flavor). We recommend you follow the brewing instructions on the box (ideal is 170F for green, white and oolong teas and 180F for black). Using cold water will not affect the polyphenols or healthy compounds in tea. If you'd like to drink our black tea iced, first dissolve it with some hot water (1oz will do), then add cold water and ice. With that said, studies have shown that cold beverages are not as beneficial for gut health as warm ones.