Section 5(3) in The Chennai Metropolitan Water Supply and Sewerage Act, 1978
(3)Subject to the provisions of this Act, the Board shall exercise all powers, perform all functions and carry out duties in respect of water supply and sewerage systems in the [Chennai] [Substituted for the word 'Madras' by the City of Madras (Alteration of Name) Act, 1996 (Tamil Nadu Act 28 of 1996).] Metropolitan Area to the exclusion of any department of the Government or any other existing authority.
