The body is about 60% water, give or take.
You are constantly losing water from your body, primarily via urine and sweat. To prevent dehydration, you need to drink adequate amounts of water.
There are many different opinions on how much water you should be drinking every day.
Health authorities commonly recommend eight 8-ounce glasses, which equals about 2 liters, or half a gallon. This is called the 8×8 rule and is very easy to remember.
However, some health gurus believe that you need to sip on water constantly throughout the day, even when you’re not thirsty.
As with most things, this depends on the individual. Many factors (both internal and external) ultimately affect your need for water.