An example of filtration is making tea, where a filter or sieve separates tea leaves from water, allowing only the liquid tea to pass through while retaining the leaves. The liquid obtained is called the filtrate.Other examples include filtering sand from water using filter paper or muslin cloth, coffee brewing with a coffee filter, and air filtration using HEPA filters to remove dust and pollen. Biological filtration also occurs in kidneys filtering blood.Filtration works by passing a mixture through a porous medium that allows only certain particles (like liquids or smaller molecules) to pass, trapping larger solid particles.