I just had my Count Consort die of thirst, while standing in 6/7 depth flowing freshwater. Very peculiar.
The story of how he got there demonstrates that sometimes things go right after all.
I did not have rooms prepared for my nobility when they arrived, on account of having been delayed by a magma pipe that was not anywhere near where I expected to find it. That is, it was in the third quarter of the map that I searched. Since I had a Grand Dining Room, a good food supply, and plenty of booze I decided to leave them waiting while I made proper quarters for them.
A large goblin siege killed the Human diplomat the next time the Human caravan arrived, and they left without selling me either booze or wood for barrels. Now I was in trouble.
When the booze ran out, the Countess began throwing tantrums. In one of these tantrums, she broke a floor grate in the waterfall chamber of the dining room. I quickly had it replaced, but failed to check to see if anyone had fallen in before the new grating was installed.
After several tantrums the Countess went berserk and was killed. I realized that I was going to have to dispose of her consort. When I went looking for him, lo and behold he was in the drainage chamber under the waterfall.
According to the architecture of my waterfall chamber, the only way he could have gotten there was by falling through the hole she made in the floor. The well is not connected to the waterfall, and it drains off the map through a fortification.
The Count Consort was covered in water and evidentally learning to swim, because I got a message saying he had gained skill in something. He was exhausted, hungry, and, yes, thirsty. Eventually he died of thirst, essentially done in by the Countess whose death made his a requirement.