The point is that the 8 glasses of water a day thing is bullshit. I see people carrying giant jugs of water around all the time and people commenting on basically forcing this on themselves. Drink when you're thirsty. That's all you need to do.
8 glasses of water is pretty close to the suggested amount. Adequate average daily intake is 15.5 cups for men, and 11.5 cups for women. The saying doesn't say how large is a glass, but 16 cups is 8 16oz glasses, or with 20% from food, 8 12oz glasses.
I live a mile in elevation, if I wait till I am thirsty to drink, my hands turn to ash, my voice gets coarse, and my brain turns to mush. Not everyone has the same needs. Don’t worry about anyone else drinking too much water please.
The first time I visited Denver I walked around a lot and was very confused why I felt hungover when I hadn’t been drinking. I was living in Louisiana at the time, which is at sea level and very humid!
I notice very few effects of "under-drinking". So yeah, not everyone has the same needs.
On the flip side, I was working outdoors in the sun all day today, and probably ended up drinking about 2 gallons of water without needing to pee much. So not everyone has the same needs even on a day to day basis.
Your specific circumstances don't change the general rule, which is that for most people and under most conditions, hydration status is correctly balanced by thirst. There are indeed exceptions, such as when getting older, which I addressed in my initial comment.
