Section 115(8)(b) in The City of Nagpur Corporation Act, 1948
(b)(i)the water tax of so many per centum of their annual value, as the Corporation may consider necessary for providing water supply;(ii)an additional water tax which shall be called "the water benefit tax" of so many per centum of their annual value, as the Corporation may consider necessary for meeting the whole or part of the expenditure incurred or to be incurred on capital works for making and improving the facilities of water supply and for maintaining and operating such works;