5. Eat Food: The rule of thumb governing survival hydration and food is a simple rule. If you have nothing to drink, then do not eat. Eating anything, even watery foods, takes water from your system to create the slurry that will be able to move through your GI tract. Eating without drinking can lead to constipation, or worse, an intestinal blockage. If you are suffering from dehydration, and have watery foods available—try squeezing out the liquid through a cloth. I'll often do this with summer berries to create a drink. Blueberries, raspberries, blackberries, and other watery wild edibles can be mashed and squeezed to make a juice that offers hydration and even a few calories and vitamins, without wasting the water it would take to pass all those skins and seeds.