The discharge of sewage into the sea is prohibited, except when:
(1) the ship is discharging comminuted and disinfected sewage using an approved system at a distance of more than 3 nautical miles from the nearest land, or sewage which is not comminuted or disinfected at a distance of more than 12 nautical miles from the nearest land, provided that in any case, the sewage that has been stored in holding tanks shall not be discharged instantaneously but at a moderate rate when the ship is en route and proceeding at not less than 4 knots; the rate of discharge shall be approved by the flag State Administration based upon standards developed by IMO; or (2) the ship has in operation an approved sewage treatment plant (provided that its test results are in the International Sewage Pollution Prevention Certificate and the effluent does not produce visible floating solids nor cause discoloration of the surrounding water). (Annex IV Reg. 11)
