Ballast water is water carried in ships’ ballast tanks to improve stability, balance and trim. It is taken up or discharged when cargo is unloaded or loaded, or when a ship needs extra stability in foul weather. When ships take on ballast water, plants and animals that live in the ocean are also picked up. Pump that are capable of pumping ballast water are crucial for the operation of most vessels. They deliver water in and out of the ballast water tanks; when it is loading, off-loading and trim of the vessel. Ballast water is generally seawater. It is pumped into tanks known as ballast tanks. These tanks are filled by the ballast pump in order to add weight to the ship. When cargo has been discharged, it is used to improve vessel’s stability. Ballast tanks reduce the centre of gravity on the vessel. It is to enable the crafts to be stable.