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
- 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!