How much water is necessary for an astronaut to drink every day?

The average person needs to drink around 2 liters of water per day. In space, the human body loses fluids much faster than on Earth, due to the lack of gravity. This is because the body does not have to work against gravity to keep fluids in the body, so more fluid is lost through sweating and respiration. As a result, astronauts must drink around 3 liters of water per day to stay hydrated.