Teacher Area

Introduction: Human Need for Water (continued)

Important Content (accompanies Human Needs for Water PowerPoint)

A person can go without food for several weeks in necessary, but without water life cannot last more than a few days. The human body is 70 percent water. We take in water with food and drink, and lose it in urine, in sweat, and in our breath (as water vapor).

In one day the average person loses between 2 to 3 quarts (that's 8-12 cups) of water through their urine, sweat, and normal breathing. If a person doesn't replace that lost water, then dehydration begins to occur.

  • At 1-2% dehydration, thirst is perceived.
  • At 5% dehydration, a person becomes hot and tired, and strength and endurance decrease.
  • At 10% dehydration, delirium and blurred vision become a problem.
  • At 12-20% dehydration, a person dies.

Pause and reflect on that for a moment. A person loses 2 to 3 quarts of water every day as a result of their normal body functions. Which means if a person doesn't get any fluids for about three days, they will die.

Most people have never thought about the above because they have NEVER been personally confronted with an extended shortage of fresh safe drinking water at any time in their lives.

(This site identified here summarizes the rule of thumb for survival and discusses the human body's need for water.)


Feel free to add questions to the game play and quiz as time permits. The content below would be valuable added content.

Other Content:

Water and the Human Body: ( Source: Every Body Counts, Every Drop Matters, UN Classroom Resource Guide; Water Facts Website trivia)

The human body is 70% water

  • The human brain functions clearly with 90% water
  • Blood is 80% water
  • If you use 1% of your body's water, you feel thirsty
  • If you use 5% of your body's water, you will have a fever
  • If you lose 10% of your body's water, you will not be able to move
  • Losing 12% of your body's water results in death
  • Most people can exist for over a month without food, but less than a week without water.
  • Even MILD dehydration will slow down one's metabolism as much as 3%.
  • One glass of water will shut down midnight hunger pangs for almost 100% of the dieters studied in a University of Washington study.
  • Lack of water, the #1 trigger of daytime fatigue.
  • Preliminary research indicates that 8-10 glasses of water a day could significantly ease back and joint pain for up to 80% of sufferers.
  • A mere 2% drop in body water can trigger fuzzy, short-term memory, trouble with basic math, and difficulty focusing on the computer screen or on a printed page.
  • Drinking 5 glasses of water daily decreases the risk of colon cancer by 45%, plus it can slash the risk of breast cancer by 79%, and one is 50% less likely to develop bladder cancer.


The State of the World's Freshwater: (Source: The United Nations, Division for Sustainable Development)

  • 1.2 billion people lack access to safe water, roughly one-sixth of the world's population and 2.4 billion or 40 percent of the world's people lack access to adequate sanitation services.
  • Some 6,000 children die every day from diseases associated with unsafe water and poor sanitation and hygiene.
  • Unsafe water and sanitation cause an estimated 80 percent of all diseases in the developing world.
  • Women and girls tend to suffer the most as a result of the lack of sanitation facilities.
  • One flush of a Western toilet uses as much water as the average person in the developing world uses for a whole day's washing, drinking, cleaning and cooking.
  • Water use has grown at twice the rate of population during the past century. The Middle East, North Africa and South Asia are chronically short of water.
  • In developing countries, as much as 90 percent of waste water is discharged without treatment.
  • Over pumping groundwater for drinking water and irrigation has caused water levels to decline by tens of meters in many regions, forcing people to use low-quality water for drinking.
  • Losses of water through leakage, illegal hook-ups and waste amount to about 50 percent of water for drinking and 60 percent of water for irrigation in developing countries.
  • Floods affected more than 75 percent of all people impacted by natural disasters during the 1990s and caused over 33 percent of the total estimated costs of natural disasters.

On Water Consumption: (Source: Every Body Counts, Every Drop Matters, UN Classroom Resource Guide)

  • A Masai person in Kenya will use 10 litres (3 gallons) of water per day
  • An average Canadian uses 326 litres (86 gallons) per day
  • An American person in Los Angeles will use 500 litres (132 gallons) of water per day
  • An average person in India uses 53 litres (14 gallons) per day
  • An average person in Japan uses 292 litres (77 gallons) per day
  • An average person in Switzerland uses 405 litres (107 gallons) per day

On Water Usage: (Source: Jefferson County Water Issues; Ecological Integrity: Integrating Environment, Conservation and Health (Island Press, Washington DC , 2001)

  • It takes 2072 gallons of water to make four car tires
  • It takes 24 gallons of water to produce 1 pound of plastic
  • It takes 1851 gallons of water to refine one barrel of crude oil
  • It takes 60 gallons of water to produce 1 pound of potatoes
  • It takes 108 gallons of water to produce 1 pound of wheat
  • It takes 240 gallons of water to produce 1 pound of soybeans
  • It takes 12,009 gallons of water to produce 1 pound of beef

More water facts can be added to the slide show and tests if desired.


  • Oceans (saltwater) = 97.2%
  • Fresh water = 2.8%


  • Ice caps and glaciers = 82.1%
  • Groundwater (aquifers*) = 14.3%
  • Surface water (lakes, rivers, and streams) = 2.4%
  • Air and soil = 1.2%