Brief Description:

Students will create a water filter, attempting to make the dirty water given to them as clean as possible.

Grades: 5, 6, 7, 8

Time: 1 hour

Keywords: filter, environmental engineering, clean water

Lesson Objectives

  • Students learn about water filtration and water quality
  • Students will understand how different materials filter differently


  • Dirty water: can use things such as: glitter, dirt, leaves, small sticks, food coloring, oil
  • plastic cups (2 per group)
  • 1 Funnel per group (create your own by cutting the tops off of 2L bottles)
  • cotton balls
  • uncooked beans and/or rice
  • gauze
  • coffee filters
  • Square of cheesecloth
  • Tape
  • Paper
  • Popsicle sticks
  • Charcoal bits
  • Sand


  1. Discuss potable water, water quality, and filtration.
    1. Potable water is water that is safe for drinking. What do students think makes water suitable for drinking?
    2. Water quality refers to the chemical, physical, biological, and radiological characteristics of water. It is essentially a measure of the “cleanliness” of water.
    3. Water filtration is the process by which impurities are removed from water.
  2. Introduce the challenge: Students must take the dirty water and try to make it as clear and clean as possible using the materials provided.
  3. Have students plan what materials they will use to filter their water.
    1. Students can filter it in iterations, meaning they can pour their water through multiple filters or repeat the same filter multiple times. (Example: Step 1: remove the large objects with X material. Step 2: remove the smaller objects with Y material. Step 3: remove the oil using Z material).
  4. After 30 minutes of filtering, allow students to bring their cup of “clean water” to the front of the classroom. Compare the differences between the cups. Are some cups clearer than others? What did those groups do that others did not? What worked to remove bigger objects? What worked to remove oil? What did not work?

Extensions and Modifications:

  • To add a story/context:
    • Pretend that a ship and its crew were shipwrecked and need to engineer a way to survive. In order to survive, the crew recognizes the need for water. The crew finds a bucket of dirty water in the galley wreckage, but it is filled with oil, rice, tea, and other non-drinkable materials. Using the few materials you have, design a solution to create clean, drinkable water.



  • Limit the amount of materials groups can use

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