The amount of drinking water required per day is variable. It depends on physical activity, age, health, and environmental conditions. In the United States, the Adequate Intake for total water, based on median intakes, is 3. 7 litres (130 imp fl oz; 130 US fl oz) per day for human males older than 18, and 2. 7 litres (95 imp fl oz; 91 US fl oz) per day for human females older than 18 which includes about 80% from beverages and 20% from food. The European Food Safety Authority recommends 2. 0 litres (70 imp fl oz; 68 US fl oz) of total water per day for adult women and 2. 5 litres (88 imp fl oz; 85 US fl oz) per day for adult men. The common advice to drink 8 glasses (64 ounces) of plain water per day is not based on science, and an individual's thirst provides a better guide for how much water they require rather than a specific, fixed quantity. Americans age 21 and older, on average, drink 1,043 mL (36. 7 imp fl oz; 35. 3 US fl oz) of drinking water a day and 95% drink less than 2,958 mL (104. 1 imp fl oz; 100. 0 US fl oz) per day. Physical exercise and heat exposure cause loss of water and therefore may induce thirst and greater water intake. Physically active individuals in hot climates may have total daily water needs of 6 litres (210 imp fl oz; 200 US fl oz) or more.