A simple water target
One common rule is about 35 ml per kilogram of body weight (roughly half an ounce per pound), then a bump for heat or training. 75 kg × 35 ml is about 2.6 litres. Thirst, urine colour, illness, and medical conditions matter more than any formula. This is not medical advice.
Common questions
Do coffee and tea count?
They add fluid. Plain water is still the easy default.
Can I drink too much?
Yes. Do not force gallons. Stop if you feel bloated or confused and get care.