6-8 glasses a day is considered normal (about 2 litres) but obviously if it's hhot you'll need to drink more to keep yourself hydrated. You don't want to go the other way and drink too much (more than 8 litres a day) cause that can physically cause you to drown yourself as it sends your kidneys into malfunction mode x
My dr told me atleast a gallon a day! Which is so hard. Lol but i have a constant battle with kidney stones i have too..but if u put a lemon or lime slice in it that seems to help!
That's like 4 litres, that's quite a lot.... x
You are supposed to drink half your body weight in ounces. Say you weigh 150lbs, you would need to drink 75oz of water a day.