Water treatment refers to physical and chemical measures taken to make water quality reach a certain standard for use.

The purpose of water treatment is to improve water quality to meet certain water quality standards. According to the different treatment methods, there are physical water treatment, chemical water treatment, biological water treatment, etc. According to the different object of treatment or purpose, there are two categories of water supply treatment and wastewater treatment. Water supply treatment includes domestic drinking water treatment and industrial water treatment; Waste water treatment has domestic sewage treatment and industrial waste water treatment.

Water treatment includes: sewage treatment and drinking water treatment two kinds, some places also put the sewage treatment is divided into two kinds, namely sewage treatment and water reuse two kinds.