I'd say moer like a day to feel "Hungry", 48 hours to start feeling the true blood lust, and yeah, by 72, he'll be a bit in hell over the hunger.

For me, and my understanding of vampires, they don't "Need" anything other than blood, so for me at least there would be no need to drink water, nor would they feel thirsty for anything but blood, but if you wanna go with needing to drink water for this RP, I don't mind.