Water is my top choice.
Water itself does not carry any special taste. But can with simple means by a slice of cucumber, orange, citrus, or a mint leave and ice, become some thing extra.
Also taste of water differs alot. From where you get your water. The sorroundings around where your city drains water gives it the taste. Also water taken from some wells can have very distinct taste.
I'm lucky to be able to drink water from my tap, with no harms done. I have also had water in USA and it is bloody awful, polluted with loads of chlorine.