The light reactions use the reactant water from the equation and release the product oxygen.
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).
