The PWA is responsible for the production and distribution of potable water that meets WHO standards to 74 provinces throughout Thailand—all except Bangkok, Samut Prakan, and Nonthaburi)—which are served by the Metropolitan Waterworks Authority.

[1] The Provincial Waterworks Authority was established on 28 February 1979, as a state enterprise under the jurisdiction of the Interior Ministry.

When the performance of these two agencies was found wanting, the government shifted water supply affairs, along with officials and employees, transferred from DOPW's provincial waterworks division and DOH's rural waterworks division, to the newly created Provincial Waterworks Authority.

[2] As of end-May 2014, the PWA had 7,730 employees, 987 of them working at Bangkok headquarters, and the remaining 6,743 staffers working at 10 PWA regional offices and 233 waterworks across the country.

A sister-agency, the Metropolitan Waterworks Authority (MWA), provides water services to 2.1 million households (12.5 percent) or 8.4 million persons in Bangkok and two neighboring provinces.