A Study of Your Domestic Water Supply

Janis Lariviere and Sara DeMott
1991 Woodrow Wilson Biology Institute


Students will follow a raindrop from its source into the water supply for their houses and then back to the environment. The students will draw and/or understand a diagram of a water treatment plant and a sewage treatment plant.


Water is essential for life to exist as we know it. Without water, a person will most likely die in four days. The water on Earth is continually recycled. When it rains, water gets into the ground, entering wells, rivers and reservoirs. Before it comes to your house, water is usually treated to ensure that you do not get diseases from the water. After you use it, the water that leaves the drains in your house must be treated again before it reenters the environment. Once back in the environment, it may evaporate, getting into the air where it will condense and rain will again fall. This is called the WATER CYCLE.

Water that is safe to drink is referred to as being POTABLE. Thus, it should not contain organisms or chemicals that are harmful to us. The water is NOT pure. Pure water has no other substances in it at all. It is very expensive to purify water.


  • Materials describing your local water treatment plant
  • Materials describing your local sewage treatment plant
    (These materials can be obtained from your local plants.)
  • Optional - speakers from the above kinds of plants


Read the materials listed above. Work in groups of three students. Discuss the water cycle and the treatment of water which you use. Draw a diagram of what you think your water system looks like. Show how water from a river, a reservoir, or a well is treated before it enters your house. Then, show the house and treatment of the water before it reenters a river or other body of water.

If possible visit a local water treatment plant and/or a local sewage treatment plant. After the field trip, compare your diagrams with what you actually saw on the trip. Make additions to your original diagrams so you have a clear understanding of a domestic water system.

After the diagrams are complete, write a paragraph describing what happens to a drop of water from the time it hits the ground as rain, through a domestic water system, and evaporates and becomes a drop of rain a second time.

Option 1:

If it is not possible to take a fieldtrip, provide the students with a diagram of their local water and sewage treatment plants. Have the students (in groups) write a story following a drop of water from the time it hits the ground as rain, goes through a domestic water system, and evaporates and becomes a drop of rain a second time. They should write the story in a sequential sentence format with each sentence on a separate strip of paper. They should then shuffle the strips and give them to another group to put in the right order. Below are examples of diagrams and related sentences. These were prepared by Dr. Kathryn Eidson concerning St. Louis water treatment, titled The Life and Times of Sludgy Drano Drop.

Option 2:

Provide the students with an already constructed set of jumbled sentences concerning their water to sequence.


Click on graphic to enlarge

primary treatment

Primary Treatment

secondary treatment

Secondary Treatment

advanced treatment

Advanced Treatment

sludge processing

Sludge Processing

city map with sewage layout

Map of sewage system

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