Section 11(1)(b) in The Merchant Shipping (Prevention of Pollution by Sewage from Ships) Rules, 2010
(b)the ship has in operation the sewage treatment plant to meet the operational requirements as specified under clause (a) of rule 9 and -(i)the test results of the plant are laid down in the ship's International Sewage Pollution Prevention Certificate; and(ii)the effluent shall not produce visible floating solids nor cause discolouration of the surrounding water.