With version 1.4 this is how this quest worked for me:
When talking to the thirsty guy no quest as such appeared in the quest log.. he just said he was thirsty and I agreed to find some water.
Then, when picking up the bottle of water that is on the table in the middle of the kitchen, suddenly my quest-log flashed and was updated with the quest. After that happened I was able to give the water to the guy.
So to sum it up: It's the bottle of water on the table in the middle of the kitchen.. and for some reason I only got the quest when picking it up *after* talking to the guy. It might also work if you already picked it up though.
- Telemachos
