Earth Science Week Classroom Activities

Water Filtration

Activity Source:

Nebraska Earth Systems Education Network, School of Natural Resources, By Kimberly Flessner


Each group will design a water filtration system and present to the class why they picked their design.


  • 1 or 2 2-liter bottles
  • scissors
  • 1 250ml beaker
  • filtration materials (examples: soil, gravel, potting soil, cotton balls, scrap material, charcoal, sand, woodchips, Styrofoam packing, charcoal briquettes)
  • screening
  • rubber bands
  • Bunsen burner or heat source for evaporation
  • “polluted water” (tap water with salt, food coloring, sand, and dish soap added to it)


  1. Each group of 2 or 3 need to design an idea for a filtration system. Each design can use any three(3) of the filtration materials, in any order. The groups will write a short paragraph describing why they used the materials they did, and how they chose their order.
  2. Turn the top of the bottle over (neck down) to use for the filtration chamber. Remove the cap and cover the opening with the screening, attaching it tightly with a rubber band. This is to hold the filtration materials in the chamber.
  3. The group then assembles their designed filtration system and presents their design to the class. They will explain why they chose the materials they did, and also why they arranged them in the order they did.
  4. After the presentations, or during the next class period, each group will be given a 250ml beaker full of “polluted” water.
  5. Their filtration system will be placed into the bottom to act as their collection container. Then the “polluted” water will be poured into the system and allowed to filter for 10 minutes. The collected liquid can be tested for soap right away by taking a small amount in a test tube and shaking it up. The other “pollutants” can be tested for by evaporating the water away using the heat source.
  6. The groups’ results will be compared to see which filtration system seemed to be the most successful. A conclusion statement should be written as to why they think it was the best.