My last game my vampire sims drank water almost continuously if I didn't have them doing anything else. As soon as the queue was finished they went to drink water. I think the only fix is to remove the drink water option from all sinks.
The excessive water drinking issue is the reason that I never hand out apartment keys. Whenever a keyholder comes over, they immediately go to the nearest sink and drink water. If I put that sink in the family inventory, they go right to the next available sink. For keyholders, drinking water is literally prioritized above any other interaction. Seriously, right after they finish their current glass, they instantly go for another one. They don't even clean up after themselves, just littering the whole place with empty drink glasses. Sure, my own Sims will sometimes drink water on their own, but it's not to as nearly an unbearable level as keyholders will. What I dislike more is frequent autonomous mixology drink making because that costs simoleons, unlike water.
