There are no hard and fast rule, and many people meet their daily hydration needs just drinking water when thirsty, a report on the nutritional recommendations of the Institute of Medicine National Academies. In fact, many people who are in good physical health are getting enough fluids by water and other drinks when thirsty, and also the purchase of a drink with each of your meals drinking, according to the Centers for disease Control and prevention of diseases. If you are not sure of your level of hydration, look at your urine. If it is clear, you are in good shape. If it is dark, you’re probably dehydrated.