Early sewage treatment plants were all prepared by public institutions, but they were generally public and belonged to public institutions. But to a large extent, it is self-supporting, and it is actually an enterprise. Sewage treatment generally goes through three processes: primary treatment, secondary treatment and tertiary treatment. Urban drainage and sewage treatment should follow the principles of respecting nature, overall planning, supporting construction, ensuring safety and comprehensive utilization. The competent department of housing and urban-rural construction in the State Council guides and supervises the urban drainage and sewage treatment in China. The competent department of urban drainage and sewage treatment of local people's governments at or above the county level shall be responsible for the supervision and management of urban drainage and sewage treatment within their respective administrative areas.