Water treatment refers to the physical and chemical measures taken to make the water quality reach a certain standard of use. The minimum standard for drinking water is set by the environmental protection department. Industrial water has its own requirements. The physical characteristics of water, such as temperature, color, transparency, smell, and taste, are the basic criteria for judging the quality of water. The chemical properties of water, such as its pH, dissolved solids concentration and oxygen content, are also important criteria for judging water quality.