How to turn food coloring water into clear water for a kid's experiment

Written by kelly sundstrom
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How to turn food coloring water into clear water for a kid's experiment
You can turn coloured water clear by using a filter. (Dynamic Graphics/Dynamic Graphics Group/Getty Images)

When you filter your drinking water using a commercial water filter, you may not realise how many particulates and microbes are removed before you drink the water. One way to understand this process more clearly is to create a water filter using a few materials that you can find around the house or purchase. Once complete, your homemade water filter can transform coloured water into clean, clear water.

Skill level:
Moderately Easy

Things you need

  • 2-liter plastic bottle
  • Knife
  • Cotton balls
  • Sand
  • Pea gravel
  • Glass jar
  • Food colouring

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  1. 1

    Cut a 2-liter bottle in half crosswise. Place the top half that includes the neck and mouth of the bottle upside down inside the bottom half. The top half of the bottle should look like a funnel inserted into the bottom half of the bottle.

  2. 2

    Place cotton balls into the "spout" of the top half, then pour 1 inch of sand on top of the cotton balls. Cover the sand with 1 inch of pea gravel to complete the filter. The gravel will filter out larger materials, the sand will filter finer materials, and the cotton balls will filter out tiny particles.

  3. 3

    Pour 4 cups of water into a glass jar, and add 10 drops of food colouring. This will make the water brightly coloured.

  4. 4

    Pour the coloured water over the pea gravel in the top of the device. The water will pass through the gravel, sand and cotton balls, effectively filtering out all of the food colouring. The clean and clear water will come out the spout into the bottom half of the bottle.

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