Huge Ocean Waves

Water Purification Project

Every living being on Earth needs clean water to function. Humans must consume at least two liters of purified water each day. Advancements in technology ensure that drinking water is safe and contaminant-free. This science project aims to help explain how water purification works.

Caution: The resulting water is not safe for consumption. This project is merely for demonstration.

What you need:

  • Timer or stopwatch
  • Spoon (for scooping alum)
  • A large spoon for stirring
  • A rubber band
  • A coffee filter or filter paper
  • 1 cup of small pebbles
  • 1 cup of coarse sand
  • 1 20-ounce cups
  • 1 1000-ml beaker
  • A 2-liter soda bottle (cut in half)
  • A 2-liter soda bottle with a lid
  • Half a liter of tap or swamp water with dirt or mud


How to make it:

  1. Place the swamp or tap water in the 2-liter bottle with a lid. Describe how it smells and looks.
  2. Attach the lid to the bottle. Shake it for 30 seconds (vigorously). Pour the water 10 times between two cups.
  3. Pour this water into the bottle that has no top. See how the water smells and looks.
  4. Add in 2 tablespoons of alum into the tap or swamp water in the bottle that does not have a top. Get a spoon and stir the water slowly for about five minutes. Note what happens to the water.
  5. Get the bottle that has no bottom. Secure the coffee filter to its mouth with a rubber band. Place it upside down in the 1,000-milliliter beaker.
  6. Place the pebbles into the soda bottle. Pour the rough sand over the pebbles. Then, pour the fine sand over the rough sand.
  7. Pour in two liters of clean water while keeping the sand layers intact. Remove the rinsed water out of your beaker.
  8. Next, pour in the top 2/3 of your swamp water through your filter. Also, be careful not to disturb the sediment layers you created.
  9. Compare the swamp water to the filtered water once all the water has passed through your filter. Describe how they smell and look.



The process of water filtration in this project consists of five steps:

  • Aeration

This is the process of adding air into the water. The gases trapped in the water escape. This oxygenates the water.

  • Coagulation

This allows suspended particles like dirt to stick together in a chemical way. The solid particulates become “floc” or clumps of sediment or alum. Coagulation clarifies the water and makes it colorless.

  • Sedimentation

This happens when the Earth’s gravity pulls the particulates to the bottom of your container. If the water remains undisturbed, most of the floc rests in preparation for the next process.

  • Filtration

This separates and removes the floc and particles from the water.

  • Disinfection

This is when water undergoes chemical treatment to remove pathogens.

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