Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. A water eductor or water dredge is a tool used by underwater archaeologists to remove sediments from an underwater archaeological site. Airlifts may be used for the same purpose.It consists of a large bore straight tube to which is attached a hose pipe through which clean water is pumped. The Bernoulli effect from the flow of pumped water causes suction at the mouth of the dredge. Water and sediment is sucked from the excavation site and released from the far end of the tube. The tube can be made of any rigid material such as steel or plastic. The diameter of the tube depends on the power available from the pump and whether delicate work is required.