A hell of a lot more than that. At least two gallons of water and all put together in a day.
Enough to go and take a leak every half hour to 40 minutes.
You can kill someone from over hydration.
Water intoxication
https://en.wikipedia.org/wiki/Water_intoxication
Are you a medical professional that you can dispense medical advice like this?
Or are you just a run of the mill idiot offering snake oil salesmen cures that you know nothing about.
My bet is on the latter.