The right answer is Filtration.
A water filter is composed of a filtration system that aims to separate the water from the solid particles (residues) by passing it through a porous medium, which allows only the liquids and the finer solid particles to pass through. as the filter holes (porosity). The water that comes out of this filtration system is rid of solid particles larger than the pores of the filter.
Some water filters are designed to make drinking water (very fine filtration, less than the size of a microbe).
Post the entire document please so i can find the answers to the entire thing.
I think what they rely on is there experiment and how they do it