There’s no hard and fast rule, and many individuals meet their daily hydration needs by simply drinking water when they’re thirsty, according to a report on nutrient recommendations from the Institute of Medicine of the National Academies. In fact, most people who are in good physical health get enough fluids by drinking water and other beverages when they’re thirsty, and also by drinking a beverage with each of their meals, according to the Centers for Disease Control and Prevention. If you’re not sure about your hydration level, look at your urine. If it’s clear, you’re in good shape. If it’s dark, you’re probably dehydrated.