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How Much Water Do Humans Need?

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

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Have each group use a 2,000-mL handled beaker to measure 3,000 mL of water into its large dishpan. Explain that this is the amount of water that enters the body each day through food and beverages. Ask students, What happens to the water in our bodies? Where does it go?

Present the volumes below, but do not provide the corresponding explanations. Have students hypothesize what each volume of water represents. For example, they might suggest (incorrectly) that 150 mL is the amount of water lost from tears every day.

Have one student in each group measure one of the following quantities of water from the tub into the milk jug. Be sure students use the funnel when pouring the water.  


  • 150 mL (water eliminated through the intestines)
  • 600 mL (water lost as vapor during breathing)
  • 1,500 mL (water eliminated as urine)
  • 750 mL (water lost as perspiration)


After students have finished measuring out all four examples, ask, How much water is left in the dishpan? What would happen if no water entered the body? and How can you replace water that is lost  from the body?

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