Purifying water

The colour of water depends on its impurity: less elements, and relative amount, are present, more shining is its blue, the color of purity and health.
Why water tend to be polluted? it represents the simplest way to make our works:
we use it for cooking, so putting into many organic matter;
we use it for cleaning, so putting into various kind of detergent;
we use it for carrying out our works, so putting into metals, natural and synthetic organic compounds.
All those compounds contribute to the fading of the original blue of water and humans, very recently, realized it must be restored.

How many ways to restore the blue of water?