The National Water Supply & Drainage Board had its beginning as a sub department under the Public Works Department with responsibility for the water supply and drainage systems of Sri Lanka. From 1965, it functioned as a division under various ministries until January 1975 when it was converted to a Statutory Board by an Act of Parliament.

     The National Water Supply & Drainage Board functions under the Ministry of Water Supply & Drainage. This Ministry was established in 2007 separately for the subject area of water supply & drainage. Also, the National Water Supply & Drainage Board is the only organization coming under the purview of this Ministry. Around 80% of the population has access to safe drinking water of which 30% is through piped water supply systems of the National Water Supply & Drainage Board.