Did you know that approximately 70% of your muscle, 80% of your blood is water, and 85% of your brain is made up of water? When we are born, we are nearly 90% water by weight, and as we age we lose more and more water (think of a grape slowly shriveling up into a dried raisin).
If you consume 100% fresh raw foods (with none that have been dried or dehydrated in any way), your body is receiving the cleanest, most pure water possible and you probably don't experience a lot of thirst. The less fresh foods an individual consumes, the more their needs for water increases.