Cleaning up water – looking at filtering

Today we are looking at filtering and how it can be used to clean dirty water.


What you need:

Dirty water ( or mud and clean water )

A funnel

Coffee filter/paper towel/muslin

An empty bottle


Place your filter into the funnel and pour the water through slowly.


Is the water cleaner?

Can you see the solids trapped by the filter?


There are many different ways you could construct this investigation. You could try just one filter and talk about how it traps the big bits of mud and dirt but smaller particles pass through, or you could compare 2 or 3 different types of filters to see what happens.

Is kitchen roll better than a coffee filter, would just a sieve work?

You could also work in stages, so try a colander, then a sieve and then a paper towel. Each stage should trap smaller and smaller particles.

The Science Bit

A filter is a porous material which a liquid can be passed though to separate the liquid from solids suspended in it.

We also have this post where we filtered toys.



Author: Emma Vanstone

Science Sparks, is a site dedicated to making Science fun for kids. I’d love you to follow me on my Google Profile+.

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  1. This is such a neat experiment. I bet it would be fun to let the kids think of better ways to filter the water. It will definitely give them a better appreciation for our clean water!

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  2. So simple, and yet so fun! A very good way to learn about filters and clean water. We will definitely have to try this one, thanks :)

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  3. We did that once too and it’s amazing how much gets filtered out and how gross that water still is. I think yours was more easily visble, we have very clay like dirt, so it didn’t quite dissolve right.
    Thanks for linking up to Science Sunday!

    Post a Reply


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