Dehydration occurs if the body has less fluids than it requires. Your body can’t work correctly without enough water. Depending on how much fluid you lack, you may have moderate, mild or severe dehydration. By sweating, breathing, urinating, and pooping as well as through tears and saliva it is natural to lose fluids every day. Normally you restore the lost liquid by drinking water and other liquids containing water. You can be dehydrated if you lose too much water or do not drink or eat enough.