The Metropolitan Waterworks Authority (MWA) was established on August 16, 1967, in accordance with the Metropolitan Waterworks Authority Act 1967 by consolidating 4 preceding agencies namely; the Bangkok Waterworks Authority of the Municipal Public Works Department, Thonburi Waterworks Authority of Thonburi Municipality,Nonthaburi Waterworks Authority under the Provincial Waterworks Division of the Municipal Public Works Department, and Samutprakarn Waterworks Authority of Samutprakarn Municipality called “the Metropolitan Waterworks Authority”.

The Bangkok Waterworks Authority inaugurated its service on November 14,1914 under the Department of Sanitation, Ministry of Municipality, afterward, changed to be the Municipal Public Works Department, the Ministry of interior. Subsequently, the Bangkok Waterworks Authority was transferred to be under the Bangkok Municipality in 1939, and transferred back to the Municipal Public Works Department in 1952 and finally established to be the Metropolitan Waterworks Authority on August 16, 1967.

The Thonburi Waterworks Authority, initially obtained treated water to supply in its area from the Bangkok Waterworks Authority via the distribution pipes along with the King Rama I Bridge. Later, during the World War II, the Bridge was bombed by plane, thus treated water unable to be distributed from Bangkok to Thonburi area. Therefore, the Thonburi Municipality started to implement its waterworks operation by drilling deepwells water and supplied to the people in the area in 1953, and later merged to MWA in accordance with the MWA Act 1967, the MWA has taken over the operation on August 14,1968.

The Nonthaburi Waterworks Authority was operated on January 15,1960, under the supervision of the Municipal Public Works Department, Ministry of Interior, and transferred to consolidate with the MWA in accordance with the MWA Act 1967, the MWA has taken over the Nonthaburi Waterworks Authority on December 14, 1967

The Samutprakarn Waterworks Authority was inacgurated its service on June 20, 1936, under the control of Samutprakarn Municipality, and combined with the MWA in accordance with the MWA Act 1967, the MWA has taken over its operation on March 22,1969.