Adults below the age of 60 should be drinking 35ml per kg per day. 60 and above is 30ml per kg per day.
This is a general rule and doesn’t fit everyone. People who are obese often shouldn’t follow this rule because there’s potential for fluid overload, which puts them more at risk of things like pulmonary odema or congestive heart failure. But it’s a good rule to keep in mind and to aim for.
Don’t force yourself to drink if it’s uncomfortable- that’s your body’s way of telling you it’s enough. It’s good to be conscious of how much you drink, but overall your own body will tell you how much it needs. A better practical rule is that if you’re feeling hungry, have a glass of water before you do anything else. That’s usually an easy way of getting some extra fluid intake.
But overall it’s not necessary to be so strict with it unless there’s a problem or if you have symptoms related to it.