Water Crisis: How Mathematicians Save the Planet

Last week, we learned about the percentage content of water in our bodies and in the foods we consume. We also learned how much water we need to consume each day to stay hydrated and healthy. This week, we learned about how much water we have to sustain a healthy life.


70% of the Earth is covered in water but only 3% of that is fresh water; the other 97% is saline ocean water. Most Americans have heard of  the drought in California and how they have huge desalinization plants to turn ocean salt water into drinking water for its citizens. Unfortunately this process costs billions of dollars and most countries cannot afford even a fraction of that cost. Even boats can have water makers but the installation costs thousands of dollars. But haven’t we been doing just fine with the 3% fresh water that we have?



Of the 3%, close to 70% is in glaciers and icecaps and close to 30% is underground; only 0.3% is surface water that we can easily access; and of that .3% of the 3% of the 70%, 87% is in lakes, 11% in swamps and 2% in rivers.


When I was a Mathlete in the 1960s, the world population was about 3 billion people and we all had enough water. Now we have over 7 billion people and by the year 2060 is predicted that we will have over 10 billion. Almost 3 billion people in the world cannot access fresh water or cannot afford to transport it to their villages. Yes, over one million children die each year from drinking contaminated water. I told our Mathletes that they live in the safest place in the world and they will always have water; however, they can do their part to conserve water individually.


See the attached pdf of graphics regarding the water crisis. It shows that the countries that have physical water scarcity are in Northern Africa: Algeria, Libya, and Egypt. In the Middle East: Saudi Arabia, Iraq, Turkey, Iran, Pakistan, Afghanistan, much of India, Northern China and some smaller countries. The continents and countries with economic water scarcity are Central and most of South American, central and much of southern Africa, China, Viet Nam, Laos, Cambodia, the Philippines and the rest of the East Indies, and Australia.


From the pdf, the countries that consume the most water are United States, Australia, Italy, Japan, Mexico, Spain, France and Austria. And the countries that consume the least water are China, Bangladesh, Kenya, Ghana, Cambodia, Ethiopia, Haiti, and Mozambique.


What is the relationship between a country’s wealth and its water consumption? In most cases, with a few exceptions, the amount of wealth determines the amount of water consumption. In other words, the greater the wealth of a nation, the more water it consumes, and conversely, the less wealth a nation has, the less water it consumes.


In places of water scarcity, 80% of all child death under the age of five is related to diseases associated with a lack of clean water. Contaminated drinking water can cause severe diarrhea, a variety of other gastrointestinal disorders, and cause the accumulation of life disabling or fatal toxins in body tissues.


1. There is not enough physical water available to support a nation’s needs for its population.

2. There is not enough money to deliver the water to the places that need it for drinking or for agriculture.

3. There is not enough money to clean the water to make it usable for drinking or for agriculture.


Water scarcity is projected to increase as population increases and puts more demands on water to meet the basic needs of people.


As underdeveloped countries become more industrialized, the trend is to consume more food that requires more water to produce.


The average American consumes over 150 gallons of water per day. During class, I showed the class how my family lives on 5 gallons of water per day during the summer (boat water tank has 84 gallons distributed among four people or 21 gallons per person and we stretch this tank over 4 days so 21/4=5.25 gallons per person per day). This can only be done by conserving water at every opportunity.


First I had the children estimate how many times a week they did the following activities: bath, shower, teeth brushing, hands and/or face washing, and toilet flushing. We looked at the average gallons of water to do each activity and multiplied (with the older grades) the number of weekly activities times the gallons used. Then we talked about mathematical conservation for each activity. The opposite side of the page was left blank to do this activity with parents which also included dishwashing, clothes washing and watering the lawn.


The next activity was to look at the gallons of water it takes to produce the products we use and the food we eat. For example, it takes about 41,000 gallons of water to produce a car, 400 gallons of water to produce a t-shirt, etc. While a pound of lettuce requires 15 gallons of water to produce, it takes over 2,800 gallons of water to produce a pound of chocolate.


I had the children write these numbers down respecting place value so they could add the gallons of water used at the bottom (K/1 may only want to write these numbers down).



The goal of this lesson is not to make the children feel guilty about the water they consume nor is it to have them stop doing certain activities or stop eating certain foods. The objective is to educate them so they make informed decisions about what they consume. Before they buy that next pair of jeans which requires 1,800 gallons of water to produce, maybe the old pair is not so bad. Before they have that next hamburger, know that it takes about 1,250 gallons to produce that quarter pounder. Maybe they still eat beef but just less often, maybe they still eat chocolate on halloween but just not a pound of chocolate. Have fun and live responsibly as a mathematician who makes informed decisions.

Water_Consumption_Weekly_Reduce_Water_Footprint.pdf57.09 KB
Water_in_Gallons_to_Produce_Items_and_Food.pdf90.95 KB
Water_Crisis_Graphics.pdf1.89 MB