Caffeine High

Okay, so let's say a cup of coffee has 100 mg of caffeine, and a cup of tea made from a single tea bag has 50 mg, what would happen if you dipped the tea bag into a cup of coffee? Would the caffeine level increase all the way to 150? Or does saturation happen before that? Or does the effect multiply?

Water is good for you

Why don't they make cans of non-carbonated water? We have bottles and cans of juice, pop, beer, etc. Why aren't there cans of water?