First, let’s bust a myth: the “eight glasses a day” rule is more of a gentle suggestion than a hard-and-fast law. Your body is a clever machine that adjusts based on your size, activity level, and how much you’ve been sweating from that dance-off in your living room. The actual safe upper limit for a healthy adult is around 0.8 to 1.0 liters per hour, with a total of 3 to 4 liters per day being perfectly fine for most people.
If you’re a marathon runner, you might need more—up to 6 or 7 liters—but please, do not try to set a personal record by chugging a gallon during a Netflix binge. Your kidneys will send you a very passive-aggressive email about it.
