Water filtration is an expansive topic that can refer to dozens of different processes all designed to remove impurities from water using a chemical process, a biological process, or a physical barrier.
Natural osmosis occurs when solutions with two different concentrations are separated by a semi-permeable membrane.
Water softening refers to a method of filtration by which “hard” water is made soft.
Ultraviolet radiation is a method of disinfection involving the use of a high concentration of ultraviolet light at a short wavelength.
Distillation has been a mainstay in water treatment for thousands of years, being touted by Aristotle as an effective means of purification as far back as 350 B.C.E.