The average adult loses about 2.5 litres water daily through perspiration, breathing and elimination. Symptoms of the body's deterioration begins to appear when the body loses 5% of its total water volume. In a healthy adult, this is seen as fatigue and general discomfort, whereas for an infant, it can be dehydrating. In an elderly person, a 5% water loss causes the body chemistry to become abnormal, especially if the percentage of electrolytes is overbalanced with sodium. One can usually see symptoms of aging, such as wrinkles, lethargy and even disorientation. Continuous water loss over time will speed up aging as well as increase risks of diseases.
If your body is not sufficiently hydrated, the cells will draw water from your bloodstream, which will make your heart work harder. At the same time, the kidneys cannot purify blood effectively. When this happens, some of the kidney's workload is passed on to the liver and other organs, which may cause them to be severely stressed. Additionally, you may develop a number of minor health conditions such as constipation, dry and itchy skin, acne, nosebleeds, urinary tract infection, coughs, sneezing, sinus pressure, and headaches.
So, how much water is enough for you? The minimum amount of water you need depends on your body weight. A more accurate calculation, is to drink an ounce of water for every two pounds of body weight.