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Who Dirtied The Water/Clean Water:
Is It Drinkable?

By Carmen Hood

Modified by Carmen Hood from the SEER Water Project and Ginger Hawhee/ Sandy McCreight (Omaha North High School, Omaha, Nebraska). Their original source is undocumented.

Type of Entry:

  • Lesson/class activity (this is actually two separate activities that work best when used together, although each is effective when used independently)

Type of Activity:

  • Life Science
  • Biology
  • Environmental Studies
  • Earth Science


During a unit studying water, my biology students participate in an activity called "Who Dirtied The water?" / "Clean Water: Is It Drinkable?". These activities can be used independently of one another or in sequence. The activities are interdisciplinary in nature and involve the use of critical thinking and analysis to solve a problem. As students enter the classroom they are handed a labeled plastic film canister. Each container holds a material that will be representative of a pollutant (ie. pencil shavings = a beaver's wood chips; plastic string = fisherman's line, etc. ). The teacher (or a student) stands at the front of the classroom next to a large beaker of clear water and begins to read a story about the history of an imaginary site. As the story comes to the name indicated on a canister, the appropriate student comes forward, opens the canister, and tells the "audience" what is inside. The contents are then dumped into the beaker of water and the water is stirred. As more and more materials are added, the story periodically asks whether the audience would boat in, swim in, or drink the water. After all mate rials are added, there should be a discussion of who is responsible for dirtying the water and who is responsible for cleaning it up. To continue the activity, each group of students is asked to design a water filtration system given only a limited number of materials (beakers, funnel, cheesecloth, charcoal, sand, ring stand, etc.) . They are asked to both sketch and write down step by step procedures. After teacher approval of their plans, they begin to filter a sample of the dirty water that had been "made" during the story. Modifications to the original design are allowed but must be indicated in their procedures and sketches. Each group's filtered water can be compared at the end of the period to serve as a spring board to a discussion of what worked and what didn't work.


*These activities, when used together, will answer the following questions:

  1. Who is responsible for pollution of water resources and the subsequent clean up?

  2. What are some of the most effective ways to clean up dirty water?

When using the activity "Who Dirtied The Water?", the more dramatic the teacher can be the better! I told my students this was story time and they would be asked to participate in helping me tell the story. When stirring the water, periodically lift up your stirring device so students can see how nasty the water does look!

If you use the dirty water produced in "Who Dirtied The Water?", you will not be able to get the filtrate from the systems to be colorless. The clarity of the water will improve, but the molasses will cause the water to remain a yellowish color.

Preparation time needed:

Preparation time for the teacher can be extensive if you are using the activities with more than one section of students. Labeling and filling the canisters does take time and you should have a separate set for each section taught , unless you have adequate prep time between classes. The filtration lab involves simply setting out the equi pment for the students to select.

Class time needed:

"Who Dirtied the Water" = 1 period
"Clean Water: Is It Drinkable?" = 2 periods.



As students enter the room, hand them a film canister that contains materials that will be added to the dirty water bell jar. The canisters will be labeled with only the entity the canister represents.

Beaver: wood chips
River: sand
Runoff: charcoal
Wetlands: dry grass
Shellfish: crushed shells
Hoodites: shells
Settlers: organic garbage
Carpenters: nails
Farmers: potting soil
Fisherman: nylon line
Houses: toilet paper
Sunbathers 1: colored paper
Sunbathers 2: newspaper
Sunbathers 3: plastic pieces
Boaters: Styrofoam
Laundromats: dish detergent
Merry Maids: baking soda
Ships: oil
Factories 1: molasses
Factories 2: vinegar

As the teacher or another student reads the story, each student with a canister will come forward, tell the class who or what they represent, describe what they think is in the canister, and add it to the water in the bell jar.

Students are to record on their data table who or what is doing the adding and the actual substance that has been added to the bell jar.

The Story:

Once upon a time there was a beautiful piece of land. It was almost an island, connected to the mainland by a narrow land bridge, and surrounded on three sides by a lake. The lake was filled with clear water and was dotted with a few small green islands. (Point to the jar). Fish and other aquatic life thrived in the water. The land was covered with trees and the land and the lake teemed with wildlife.


Would you want to swim in this lake?
Would you eat fish caught in this water?
Would you like to go boating in this lake?

Animal life flourished along a nearby river and the BEAVER were plentiful. A RIVER ran along one side of the land, carrying sediment with it as it flowed into the lake.

WETLANDS grew along the edges of the lake. Grasses from the wetlands sometimes washed into the lake and became food for the fish.

In the shallow water, clams and other SHELLFISH thrived.

A small group of people lived on this land, which they called Hoodland. The people were called the HOODITES. The Hoodite people fished for food and shellfish in the lake. They dumped some of their garbage near the lake. We still find the piles of the shells they left.


Would you want to swim in this lake?
Would you eat fish caught in this water?
Would you like to go boating in this lake?

After many years SETTLERS from Europe came to live in the area. The settlers built a town much larger than the Hoodite villages. Some of the town�s garbage was dumped into the lake. CARPENTERS built houses, farms, and stores that filled the Hoodland valley.

As the town grew, the settlers filled the wetlands to provide more land on which to build. FARMERS cut down trees to clear their fields. Without trees and wetlands to hold the soil, rain carried soil into the lake.


Would you want to swim in this lake?
Would you eat fish caught in this water?
Would you like to go boating in this lake?

More and more HOUSES and shops were built, and the town of Hoodville grew into a city. Sewer pipes were constructed to remove the waste from houses and bathrooms. The sewage flowed through the pipes into the bay.

Since the wetlands had been filled in, RUNOFF water washed pollution from the streets directly into the lake.

FISHERMAN found that nets made of plastic were stronger than those made of rope. Sometimes these nets got lost in the water.

Fisherman and other BOATERS sometimes threw their rubbish overboard.


Would you want to swim in this lake?
Would you eat fish caught in this water?
Would you like to go boating in this lake?

The city built LAUNDROMATS where people could wash their clothes. The detergents went down the pipes with the sewage into the lake.

People hired MERRY MAIDS to clean their houses. They used poisonous tile and drain cleaners, which flowed into the sewage system.

Even swimmers and SUN BATHERS going to enjoy the lake sometimes left garbage on its beaches.

As the city grew, SHIPS came to unload their supplies. Sometimes these ships spilled oil into the lake.

FACTORIES built along the water�s edge often dumped their toxic wastes and chemicals into the water.


Would you want to swim in his lake?
Would you eat fish caught in this water?
Would you like to go boating in this lake?

Reader completes the story asking:

  1. Who dirtied the water?
  2. Who is responsible for cleaning it up?




To simulate nature's water filtration system by devising a system that will filter out both visible and invisible pollutants from water.


Water is necessary to all living things. Earth is unique in our solar system having about 70 percent of its surface area covered with water. Of this water, only about three percent is potable (fit for human drinking). Of this three percent, almost two-thirds is tied up in glaciers and sea ice leaving approximately one percent of Earth's water available for use by living organisms including humans. This amount of available drinkable water is further reduced by the introduction of pollutants to our water cycle. Clean water is not a limitless resource.


  • beakers
  • rubber bands
  • nylon mesh
  • sand
  • charcoal
  • cotton balls
  • water
  • graduated cylinder
  • test tubes
  • ring stand
  • filter paper
  • dirty water


    Day 1 (Period 1):

  1. Using the available equipment, devise a filtration system that you will use to �clean� your dirty water sample.

    1. Write out, in detailed step-by-step instructions, how you will use the lab materials to filter the water sample. (Each group should have one set of instructions).

    2. Sketch your filtration system set-up and label the parts. (Each group should have one sketch).

    Day 2 (Period 2):

  2. Using your proposed filtration system, make your water sample as clean as you can.

  3. Make any adjustments to your model that are necessary in order to cleanse your water sample.

    1. Was your original filtration system successful?

    2. Describe any adjustments you made to your original model.

    3. Were you able to remove all impurities?

    4. What were some of the limitations of your system?

    5. How could you tell if your water was purified? (HINT: What physical and/or chemical changes took place that would indicate that you accomplished your goal?)

    6. What kinds of tests could you perform on your filtered water to prove that it had been cleansed?

      Research Extension: You may use library or community resources to find the following information.

    7. Describe a water purification system that could be used in a municipal area.

    8. What is Omaha's main source of drinking water?

    9. What kinds of tests are done on Omaha's water supply to meet health and safety standards?

    10. What agency sets the criteria for safety standards?

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