Earlier quoted context omitted.
What about those mornings when you want to have a 4th cup of water?
lol that's just to jump start my body before drinking coffee (which dehydrates). I drink almost a gallon a day right now outside of my jump start.
edit: here are some sources that look serious if you're interested but there's plenty of evidence. I'm an endurance athlete (so I'm mindful about dehydration) and I enjoy coffee a lot so I researched this a bit.