How Much Water is Enough


When I look out at students in the lecture hall almost everyone has a water bottle. Norbert - I think we're all hydration crazed.

I'm curious whether we're over hydrating and a new study shows we are, by a lot. The researchers created a formula to predict the amount of water the body uses a day, called WT or water turnover.

Based on data from five thousand people in twenty countries across a wide age range, they saw that men aged twenty to thirty and women between twenty-five and sixty used the most water a day.

But that can vary based on body type, air temperature, humidity, altitude and activity level. Most people take in about the same amount of water daily from both liquids and foods, and it's usually about eighty five percent of what the body uses daily.

The rest comes from breathing, skin absorption, and our metabolism. So, the amount of water we should drink is just forty five percent of WT or what we use.

And yet, men aged twenty to thirty-five drank over four liters when the study recommends less than half that. And women between thirty and sixty drank over three liters of water a day which is three times what the study suggests.

But these are general numbers. Each person's intake should vary based on their health, activity and where they live. We'd last three days without water, but for most Americans, that's the least of their worries with so many over hydrating.

And as fewer people have access to freshwater, we may all be rethinking how we use this essential resource.

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More Information

Variation in human water turnover associated with environmental and lifestyle factors
Water requirements for human consumption may become more difficult to manage as changes occur in the Earth's climate and in human populations. Yamada et al. used an isotope-labeling technique to follow water intake and loss in individuals in a broad range of environments and living conditions. Total water input and output varied according to many factors, including body size, physical activity, air temperature, humidity, and altitude. The authors derived an equation to predict water usage according to such parameters...

How much water should you drink a day? It depends on several factors.
Geography, age, environment and habits all contribute to how much water your body uses daily...

Why you don't need to drink 8 cups of water a day
Age, body size, climate, activity level and lifestyle all influence how much water your body really needs...