Excise exemption for machinery and pipes used in water supply plants requires district certification for intended agricultural or industrial use. Exempts from central excise duty machinery, instruments, auxiliary equipment and pipes used for setting up or operating water supply plants for agricultural or industrial use, subject to production of a district-level certificate by the Collector/Deputy Commissioner/District Magistrate to the Deputy Commissioner/Assistant Commissioner of Central Excise confirming clearance of the goods for the intended use; 'water supply plant' includes desalination, demineralization, purification or similar processes.