We were alerted our one cat had died suddenly in the bathtub to the sound of our other cat howling outside the bathroom door. The surviving cat then acted really strange for the next week or so.
Probably not drowned. Cats, when sick, tend to find isolated places, probably cooler, where they will lay down. Tubs seem to be a common place for cats to go to near the end.
We were alerted our one cat had died suddenly in the bathtub to the sound of our other cat howling outside the bathroom door. The surviving cat then acted really strange for the next week or so.