the answer is: "IT DEPENDS", on dozens of factors, starting with your environmental heat & humidity, and current workload. Generally, drink at least enough so

the answer is: "IT DEPENDS", on dozens of factors, starting with your environmental heat & humidity, and current workload. Generally, drink at least enough so that you pee clear once a day, and not too dark. If it is clear all the time, you may have other issues. Also, roughly follow your thirst (unless you are drinking sweetened / salted drinks).