Earth Day Activity: DIY Water Purification

Apr 7, 2023

Earth Day is almost here! It’s a special day where we think about how we can help take care of our planet.

Do you know how we can celebrate Earth Day? Let’s try making our own water cleaning system with your friends or family. We’ll learn about why water is so important and do something good for the Earth at the same time!

Question: What will happen to dirty water when you filter it through rocks, cotton balls, and sand?

Hypothesis: If I pour dirty water over rocks, cotton balls, and sand then

*Make sure to ask your #younginventor his hypothesis before moving onto the next step.


      • Cotton Balls
      • Sand
      • Rocks
      • Big plastic bottle
      • Scissors
      • Dirty water – (make your own with mixing water and dirt!)


    1. Cut the bottom off of the plastic bottle (be careful and ask an adult for help!)
    2. Take the lid off
    3. Add the cotton balls into the wide opening you just cut. Use enough to coat the bottom of the plastic bottle. (Be careful as the edges may be a little rough!)
    4. Then add your sand on top of the cotton balls
    5. Add small rocks on top of the sand!
    6. Repeat the layering all again!
    7. Pour your dirty water into the wide opening and watch the water clear up as it drips through!
    8. Filter the water back through to see how clear you can make the water!

Let’s make some conclusions! Ask your child:

      • Is this what you expected to happen?
      • Was your hypothesis correct?
      • Can you get the water to be even cleaner if you refilter it?
      • What happens to the water if you use other materials in place of the cotton balls or rocks?

What Is Happening?

Water filters work as a physical barrier that can block or trap debris (for example sand) and sometimes bacteria from passing through. Generally, the speed of the water flow will depend on the size of the gaps in the filter barrier or membrane.

Looking for a Green book?

Reading is a fantastic way to educate your children about the significance of living an eco-friendly lifestyle! In our fourth book, “We’re Going Green,” the Fairly family adopts pro-environmental concepts and practices in their daily routine. With this book, your kids will learn to be environmentally conscious, discover how they can contribute to the green movement, and become knowledgeable about real-world innovations and eco-friendly practices that are making a positive impact, such as water conservation, butterfly gardens, and solar trees!


Did you know we have a club designed for children ages 4-12 so they can learn the importance of inventions from an early age? As a member of the club, you and your children will learn all about inventions while completing fun, easy STEAM activities. We hope to spark the creativity of every #younginventor!