Make Your Own Water Filter


Make Your Own Water Filter

June 29, 2020

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Mud is a wonderful thing.

Mud is also an excellent tool for play. Experiment with us as we make our very own water filter!

Throughout history, mud has been used to build homes, create beautiful art, and even to study the past.

Using our imagination let’s go back 150 million years ago around the time when dinosaurs walked the earth. A long neck dinosaur is walking along a riverbank when (oops!) they step in a mud puddle.

Over time, that footstep is preserved within the earth amongst other rock and sediment to be discovered by paleontologists that will use that footprint to learn more about how dinosaurs may have lived.

In both the past and present, mud has also been used as an excellent tool for play! Whether you run outside after a rain shower and stomp in mud puddles, or bake mud pies in your outdoor kitchen, there are so many exciting ways to have fun with mud.

But what is mud? Mud is a goopy substance that is made of a combination of water and different types of soil. With that in mind, have you ever wondered if it is possible to separate water from mud?

With this fun science activity, you can by building your own water filter!

Let’s get started:


  • One empty, disposable water bottle with cap
  • Small push pin
  • Two coffee filters
  • Two cotton balls
  • A pair of scissors
  • Spoon or scoop
  • Craft sand
  • Playground sand
  • Gravel
  • A cup of muddy water


Carefully cut the water bottle in half. Then, using a push pin, nail, or similar object, poke four or five holes through the cap of the water bottle (we recommend an adult assist with the step). Then attach the cap onto the water bottle.

Tuck the two coffee filters into the top half of the water bottle, leaving space to place filter materials inside the coffee filter.

Rip up the cotton balls and push them into the bottom of the coffee filter.

Using a spoon, measure two spoonfuls of each filtering material into the coffee filter in this order: Craft sand, playground sand, and gravel.

Set the top of the water bottle onto the bottom half of the water bottle with the bottle cap facing down, opening with filtering materials facing up, on the bottom half of the bottle. This will catch your filtered water.

Pour your muddy water mixture inside the coffee filter, on top of the layer filtering materials. Within moments, you should see clear water dripping into the bottom of the water bottle! How cool is that?!

The science behind this DIY water filter

Remember when you layered your filtering materials? You did so in a specific order. You started with a coffee filter and cotton balls (both act as excellent filters!). Then you added craft sand, which is a very fine material. Next, you added playground sand, which has larger grains of sand. Lastly, you added gravel which are small rocks and the largest filter material that you used.

Water can slip through all the filter materials easily, but the dirt, dust, and other particles in your mud were getting caught by the filter materials. The muddy water hit the gravel first, and the gravel helped catch the mud in your water. But the gravel can’t catch all the mud, it needs help!

The next layer, the playground sand, tried to catch what the gravel couldn’t. This process continues throughout the layers in your filter, until what comes out through the cap is clear water!

Thanks for playing along with us. Isn’t mud fun?!

Important: This filtering process does not filter out germs and other small particles, so it is not safe to drink. But you can use it to water your plants!