A quick tip for mana users: in advance of Wrath of the Lich King, you can buy the next rank of “water” already.
Except it’s not water, it’s pungent seal whey. Yummy.
Still, it’ll restore your mana faster than any water’s done before – presumably because you toss it back so fast it can’t hit your tastebuds.
You can buy this charming beverage from the Inn in Ironforge – I haven’t found any other non-Northrend sources of it yet. I imagine there’s a Horde vendor that sells it too – if you’re a Hordie, please post and let me know so I can update the post!
Go ye forth and enjoy your seal whey, folks. Just ignore the smell.