Originally Posted by Botnst

"Bilge water" -- that's not a lot of water and originates within the vessel. PThe worst contaminants from bilge water are usually hydrocarbons. Bilge water disposal is regulated in most ports.

robably what you mean is ballast water. Ballast is pumped on board to trim the ship as cargo is loaded, unloaded or shifted or as fuel is burned. It is taken on as-needed and could be fresh or brackish or straight seawater. It's mostly unregulated.