There are six types of pumps used for dewatering basements or crawl spaces. All six types have their specific advantages and disadvantages. Before deciding upon a particular model, the installer must determine his requirements. The pump capacity (quantity of water pumped in gallons per minute or gallons per hour) and head (the vertical height the water is lifted, normally stated in feet of water) are measures of the pump performance. The pump capacity decreases as the head increases. Performance data supplied by the manufacturer is an important aspect in pump selection. Motor horsepower normally ranges from 1/6 to 1/2 HP Emergency DC with Battery Back-up Type Unit Emergency DC (12 Volt) With Power Pack Pedestal Type Submersible Type Sumpless Sump pumps Water-Powered Type