The Aqua Zinger is one of those products I would never think of buying myself, but now I have one it'll be something I use almost daily. It's a bottle with a little grinder system for fruit, veg, herbs whatever you fancy, that you can fill and infuse your drink with on the go.
We used fresh raspberries, which squished easily into a purée by twisting the grinder. Handy even to prepare for on icecream, never mind for adding to water. You then reattach that part to the bottle and add your water. We actually used milk to make a raspberry milkshake.
I'll be using my Aquazinger often, as I'm supposed to avoid fizzy drinks with my stomach ulcer. However if you want to add fizzy water, or even hot water, the Aquazinger is very flexible. You can purchase via their website.