March is going to be a wet month – and we don’t mean rain! This March, Australia celebrates FOUR different events related to water:

There are so many opportunities to learn about the incredible marine habitats in Australia and around the world, as well as how water interacts with the land.

Our Water & the Environment workshop covers the vital role that water plays for our planet and human life. Here’s a project that gives you a taste of the kinds of hands-on activities we facilitate in our sessions!

DIY Water Filter

Teach your students how water filters work with this fun easy project using recycled materials found at home. This project will work for all ages.

Testing of the water filter can take anywhere from an hour to several hours depending on how fast the water drips. By using natural materials that mimic the water cycle of the Earth, children can learn how the process of infiltration works and create a water filter that produces clean potable water.

Duration: 30 minutes


Per pair or group

  • Plastic soda or juice bottle
  • Vase or tall drinking glass
  • Gravel or small stones
  • Clean Sand
  • Activated Charcoal
  • Cotton balls, small cloth or coffee filter
  • Gardening dirt
  • Water
  • Scissors


  1. Cut off the bottom of an old plastic soda or juice bottle using scissors or a knife.
  2. Place the bottle upside down into the vase or tall drinking glass.
  3. Place cotton balls, cloth, or a coffee filter inside the bottle as the first layer. The first layer should be about one to two inches thick.
  4. Add an inch of activated charcoal as the second layer on top of the cotton layer.
  5. Over the charcoal, add about two inches of gravel or small stones as the third layer.
  6. Add about three to four inches of clean sand on top of the gravel.
  7. Add gravel to the bottle as the final layer. Leave about a half inch of space from the top of the upside-down bottle.
  8. Add dirt to a glass of water to create muddy water. Alternatively, get creative and add other things like glitter, beads, cooking oil or other materials to make dirty water.
  9. Pour the glass of muddy water on top of the homemade water filter and watch the water drip clean into the glass below.

Note: Many of the materials used to make a homemade water filter can be found around the house and recycled for the purpose of this project. A small washcloth, chamois cloth or coffee filter can be used instead of cotton balls. If gravel is not available, small pebbles or stones can be used. If a plastic soda bottle cannot be recycled, a large funnel can also be used instead.

Further Investigation:

As part of the experiment, children can test different materials to determine which materials produce the cleanest water. Instead of using sand and gravel, children could try rice and sponges. Kids can build several water filters using different materials to determine which materials filter ‘dirty’ water into clean water.