How to Use Cotton Balls to Demonstrate Water Pollution

When teaching someone about water pollution, it often helps to create a visual or a tactile experience to help those with different learning styles. A cotton ball filter experiment accomplishes those goals by allowing the learner to first pollute a tank of water, then filter that polluted water himself. After the water is filtered, your audience will be able to see first-hand the effects of various common pollutants on water supplies.

Things You'll Need

• 10 gallon aquarium filled with water
• 1 lb dirt
• 1 lb grass clippings
• 1 cup of gasoline
• 1 tbsp of motor oil
• 1 cup pesticide
• 1 cup dissolved fertilizer
• Candy wrappers
• Drinking glass
• Funnel
• Clear, empty plastic soda bottle, 2 litre
• Coffee filter
• Clean sand
• Cotton balls
• Activated charcoal
• Pantyhose
• Masking tape

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Instructions

• 1

  Add the various pollutants to the water-filled aquarium, which is the "water supply" in this experiment. Explain what each pollutant represents; for example, as you add the motor oil, discuss the effects of old, oil-leaking boats or jet-skis on nearby freshwater lakes, and as you add the fertilizer discuss how animal waste effects local water supplies.

• 2

  Ask your audience what they observe as you add more pollutants to the aquarium, and ask if the water is drinkable in its current state. You can drive your point home by filling your drinking glass with the polluted water and passing it around, offering it to your audience. Once you've confirmed that no one wants to drink the water, explain that these contaminants threaten many communities' drinking water supplies, although amounts are usually not so high.

• 3

  Line the large, open end of your funnel with your coffee filter, pressing the filter down into the "bowl." Add 1 inch of sand over the filter, then an inch of charcoal and a layer of cotton balls at the very top. Stretch pantyhose over the mouth and tape it to the funnel's outside walls.

• 4

  Insert the small end of the funnel into the mouth of the empty soda bottle, after removing the bottle's lid. Slowly pour the water from your glass into the funnel's pantyhose-covered mouth. Watch the water filter through the various materials and drain down into the soda bottle. The water should look far clearer.

• 5

  Remove the pantyhose from the top of your funnel. Show your audience the soiled cotton balls as an extra visual reminder of how contaminated your "water supply" was. Invite your audience to repeat the experiment using their own similar supplies and your aquarium full of contaminated water.