Water leaves your body in the urine, in your breath when you exhale, by evaporation through your skin, etc. Obviously if you are working and sweating hard then you can lose much more water. Because we are losing water all the time, we must replace it. Obviously we need to take in at least 40 ounces a day in the form of moist foods and liquids. In hot weather and when exercising, your body may need twice that amount.
Many foods contain a surprising amount of water, especially fruits.
Pure water and drinks provide the rest. Fibers Fiber is the broad name given to the things we eat that our bodies cannot digest. The three fibers we eat on a regular basis are cellulose, hemicellulose and pectin. Hemicellulose is found in the hulls of different grains like wheat. Bran is hemicellulose.