You need some soil, a jar, some water, a coffee filter paper and a fine flour sieve.

Mix the soil in the water. Your task is to get as much of the soil out of the water as possible.

First pour the water through the flour sieve. Throw away what has been trapped on the sieve.

Now place the filter in the sieve and pour the water through the filter. Throw away the filter.

Is the water clear? Would you drink it?

If the answer is no, then it means you do not believe you have fully separated the mixture.

Getting the mixture to separate is what water companies have to do – but with billions of litres! It is a tough job.