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How Much Water Do Humans Need?

Author(s): Nancy P. Moreno, PhD, Barbara Z. Tharp, MS, and Judith Dresden, MS.

Let’s Talk About It

Lead a class discussion in which students suggest different ways the body can replace water lost through natural processes. Emphasizing the body’s need for water to survive, have each group create a plan or strategy to replace the 3,000 mL of water lost by the body each day. Note that about half of the water can come from food, and that about 300 mL of water is produced inside the body daily, as energy is released from food. Have each group share its ideas with the rest of the class. 

An average human doing light work in a temperate climate loses approximately 6 pints (3 liters) of water each day. This water must be replaced. Vigorous exercise can lead to a loss of even more water. Someone doing hard work in the sun can lose as much as 20 pints of water in a day. The greatest daily loss of water ever recorded was 50 pints (more than 6 gallons)! 

Healthy humans show the effects of water deprivation (dehydration) after about three days. Death is likely when the body loses about 20% of its total volume of water.

Funded by the following grant(s)

National Institute of Environmental Health Sciences, NIH

National Institute of Environmental Health Sciences, NIH

The Environment as a Context for Opportunities in Schools
Grant Numbers: 5R25ES010698, R25ES06932

Houston Endowment Inc.

Houston Endowment Inc.

Foundations for the Future: Capitalizing on Technology to Promote Equity, Access and Quality in Elementary Science Education