So as long as the parents do their thing, I don't have to put a bowl of water in the nest or anything (seems like it would get messy or be a hazard since keeping the nest dry is supposed to be important).Well, they still receive their hydration from the parents while the parents are still feeding them. They learn to drink water after they fledge, by observing their Parents or rest of the Flock doing so.
So if you have a baby which is weaning off of wet food, then you can begin to introduce them to water by dipping their beaks ina shallow bowl (just make sure their cere doesn't submerge). After a few tries of this, they usually catch on. You can then dip their beaks 2-3 times/day, and after a few days you should notice they will go to the bowl all by themselves.
Hope that answers your Q.