Wastewater pumps are used in the collection of sewage, effluent, drainage and seepage water in locations such as homes, farms, light commercial buildings and industrial areas. Many wastewater pumps use centrifugal force or positive displacement to move fluids. Centrifugal pumps apply centrifugal force to generate velocity, use rotating impellers to increase velocity, and push fluids through an outlet valve. Positive displacement pumps use rollers, gears, or impellers to move fluid into a fixed cavity so that when liquid exists, the vacuum that is created draws in more fluid. Diaphragm pumps, the most commonly used type of positive displacement pump, include a diaphragm and chamber, as well as suction and discharge check valves to prevent backflow.