If it is, why does Standard Adventurer's Kit include a waterskin?
If you need to keep track of Rations when adventuring, wouldn't you also need to keep track of how much water you've consumed from your waterskin and worry about that supply running out?
So far, I've just played with TRs covering all eating/drinking needs (one per day while out in the field) and waterskins being for situations that required more liquid (like a journey through a desert).
I couldn't really find anything about this in the PH. What do the experts say?