Section 5(1)(b) in The Chennai Metropolitan Water Supply and Sewerage Act, 1978
(b)preparing long term plans to meet the future requirements of water supply and sewerage 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, based on estimates of demand, surveys on availabilities and usage of water and other relevant matters and periodically reviewing, revising and bringing up-to-date such plans;