These hand-operated bilge pumps don’t require corded electricity or battery power to drain a boat's bilge water. These manual bilge pumps are used on boats to drain unwanted water that enters the boat from openings on the deck, through the hull, or from a leaking propeller shaft seal. This water collects in the bilge (the lowest compartment on a boat) and often contains chemicals, particles, fuels, combustible liquids, and is pumped out using a manual bilge pump.