I drink it. Diet Peach Tea Snapple is my favorite, but I don't worry about caffeine - I still drink enough water and get all of my supplements/vitamins in every day (plus extra calcium to make up for what the caffeine is taking away).

Try the Diet Arizona Green Tea.  It is delicious and comes in gallon jugs too.  I have stocked up for 7 days of clear liquids prior to surgery. 

DC