Water treatment describes processes used to make water acceptable for various uses like drinking, industrial processes, and medical uses. The goal is to remove or reduce contaminants to fit the intended use. Processes can include physical separation methods like settling and filtration, chemical processes like disinfection and coagulation, and biological processes for wastewater. Factors in selecting treatment processes include the raw water quality, intended use, desired water quality, system size and cost. Common water treatment processes are pretreatment, coagulation, rapid mixing, flocculation, sedimentation, filtration, disinfection, and softening.