Up to 60 percent of the human adult body is water, and if we are dehydrated for a few days, we might experience some serious health problems. The water balance of our bodies is controlled by a number of organs, especially our kidneys. The water we lose via urine, stool, sweat and breathing/respiratory passage, is replaced by the food we eat or the water we drink; hence, we keep a balance without even realizing it. However, dehydration might cause serious health problems, especially in babies and the elderly. During hot and sunny days, children who play outside or children with high fever lose water. External dehydration caused by diarrhea and vomiting also lead to dramatic consequences in babies and the elderly.The most apparent indications of dehydration are the feeling of thirst, exhaustion and dry mouth. The dehydrated person feels tired and does not want to do anything. When dehydration worsens, dizziness, throbbing and hypotension begin. However, in more serious situations of dehydration, the blood pressure drops, the heart starts to pump more blood, the patient has cramps in his / her muscles, renal failure occurs and all these can lead to loss of consciousness. Medical problems in heart, brain, kidney and liver that are unveiled after serious dehydration cases can also lead other organs to fail. Preventing all these problems is easier instead of trying to cure them all. Hence patients whose water balance in heart, kidney or liver are important, should pay extra attention to their health and consult their physicians about the amount of water that they should consume a day. Unless they dehydrate more than usual, healthy people should consume around two to three liters of liquids every day.On the other hand, water consumption is very crucial for those who suffer from kidney stones or recurring urinary tract infection. Avoiding drinking water in order not to visit the bathroom might lead serious problems such as kidney stone, urinary tract infection and other illnesses about urination.People who do not like drinking a lot of water can prefer alternative liquids to keep them hydrated. Juice, tea, coffee, cold stewed fruit, ayran (salted yogurt water), lemonade, watermelon and melon are good alternatives to water. However, juice might cause medical problems for diabetics and children. Moreover patients suffering from high blood pressure should take care about the salt level while they are drinking ayran.