University of Arizona Cooperative Extension Banner drop of water
AZ Extension Water Quality  ] Youth Activities ] Glossary ]
Activity D-1: Sources of Drinking Water
This youth activity is one in a series of two activities that illustrate drinking water concepts.  It is a good introductory activity and can be adapted for all grades.

To demonstrate the sources of freshwater and just how little drinking-quality water we have on earth.
About 72% of the earth is covered with water.  The water on the earth can be divided into the following amounts:
Sources and contributing amounts (by percent) of water on Earth.
Water Source % Total Amount
Oceans 97.2
Icecaps/glaciers 2.0
Groundwater 0.62
Freshwater lakes 0.009
Inland seas/salt lakes 0.008
Atmosphere 0.001
All rivers 0.0001

The usable percentage of existing freshwater is reduced by pollution and contamination.  The amount of water that is usable by humans is very small.
* display of world or globe
* 5- or 10-gallon aquarium (or other transparent container)
* measuring cup
* plastic quart containers (enough for one for every group of three students)
* eye dropper
* 5 gallons of water
* tablespoons (enough for one for every group of three students)
  1. Show students the five gallons of water in the aquarium.  Explain that the five gallons represent all the water on the earth and five gallons equals 1,280 tablespoons of water.  Now obtain the values of water by calculating the percentages.  For example: 97.2% = oceans, so take 0.972 X 1280 = 1244.16 tablespoons.
Sources and relative contributing amounts (by tablespoons) of water on Earth.
Water Source Volume of Water (tablespoons)
Oceans 1,244.16
Icecaps/glaciers 26.24
Groundwater 7.93
Freshwater lakes 0.11
Inland seas/salt lakes 0.1
Atmosphere 0.0128
All rivers 0.0012

  1. Once the values have been determined, ask the students to calculate the volume of water other than the amount contained in oceans (this total amount is about 34 tablespoons).

  2. Divide students into teams and place 34 tablespoons of water into each group's plastic quart jar.  Then ask the students to remove the water represented by freshwater lakes and rivers (this amount is about 0.111 tablespoons or 1/10 tablespoon of water).

  3. Next ask the students to remove the amount of water represented by rivers using the eye dropper (this amount is one-thousandth of a tablespoon or less than one drop of water).
  1. Have the students consider how fragile the freshwater supply is that's available to us through rivers and lakes.

  2. Discuss with the students how dependent we are on our survival for this small percentage of water on the earth's surface (i.e., most humans can not exist for more than three days without water).  Ask students to estimate the volume of freshwater they use on a daily and weekly basis.
This activity was adapted by Dr. Kitt Farrell-Poe from Water Quality Indicators Guide: Surface Waters - A Teacher's Handbook.  United States Department of Agriculture and National Council for Agricultural Education.

wavy blue line

Issued in furtherance of Cooperative Extension work, Acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director, Cooperative Extension, College of Agriculture, The University of Arizona. The University of Arizona College of Agriculture is an Equal Opportunity employer, authorized to provide research, educational information, and other services only to individuals and institutions that function without regard to sex, race, religion, color, national origin, age, Viet Nam Era Veteran's status, or disability.

For problems or questions regarding this web contact Dr. Kitt Farrell-Poe.
This document was last modified: 31-Aug-2005 .