I drink it by the gallon (ok not quite, but I drink a lot of it). Go for it. As long as the herbal tea is made from the leaf and not the root, flower or fruit you're fine.
ive just made a litre and half of it to drink it warm so pour it into my litres and a half bottle (i know how much water im gluggling then), cold water turns down my body temp to zero degrees...i love peppermint tea..