Bananas have great water content and are especially good for restoring potassium that has vanished with dehydration. You can also try watery fruits such as cantaloupe, watermelon and strawberries. Watery vegetables such as cucumbers are good, too.
Try adding 1 teaspoon lime juice, a pinch of salt and 1 teaspoon sugar to a pint of water. Sip the beverage throughout the day to cure mild dehydration.