Bilge water is a mixture of fresh water, sea water, oil, sludge, chemicals and other fluids that accumulates in bilge wells, the lowest compartments below the waterlines of a ship.
Accumulation of contaminated bilge water into the bilge wells is inevitable as it originates from a variety of sources – tank overflows, cleaning, maintenance, drains and leaks. If the bilge wells overflow, bilge water could rise up to or above the floor plates, become a threat to the engine room, lead to accidents, emergency situations or even disturb the stability of the ship.
To avoid these risks, the bilge water is periodically pumped out of the bilge wells using bilge pumps as shown below: