The easy answer is the 8x8 rule which states that you should drink at least eight 8-ounce glasses, which equals about 2 liters every day.
In reality is more complicated than that and eight 8-ounce glasses is a good starting point. Your water intake will depend on many factors like environment, exercise, overall health, etc. Every day you lose water through your breath, perspiration, urine and other natural processes carried out by your body. This water needs to be replenish in order for your body to work properly. On average 2 - 3 liters a day will be enough for most people but if you are in hot weather or you are an athlete for example you know that 2 liters is just the starting point.
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