Science Fair Projects World

Designing a Water Filtration System


Create a water filtration system to purify contaminated water.


  • Plastic bottles
  • Gravel
  • Sand
  • Activated charcoal
  • Coffee filters
  • Dirty water (e.g., soil mixed with water)
  • Notebook for observations


  1. Cut the bottom off a plastic bottle to create a funnel.
  2. Place a coffee filter at the neck of the bottle.
  3. Layer gravel, sand, and activated charcoal inside the bottle, starting with gravel at the bottom.
  4. Pour dirty water through the filtration system and collect the filtered water in another container.
  5. Observe and record the clarity of the filtered water in your notebook.
  6. Test the filtered water for any remaining contaminants if possible.
  7. Analyze the effectiveness of your filtration system and make improvements if needed.