Physical and chemical processes for making water suitable for human consumption and other purposes. Drinking water must be pathogenically safe, free from toxic or harmful chemical or substances, and comparatively free of turbidity, color, and taste- or odor-producing substances. Excessive hardness and high concentration of dissolved solids are also undesirable, particularly for boiler feedwater and industrial purposes. The treatment processes commonly used are sedimentation, coagulation, filtration, disinfection, softening, and aeration. A recently developed water treatment technology uses pressure-driven membranes as a barrier to pollutants.