| Flow rate at the required lift | Pump-curve flow at the expected total dynamic head, stated in gallons per minute (GPM) or litres per minute (L/min). | Flow generally decreases as the pump works against more vertical lift and pipe resistance. A pump’s advertised maximum flow is usually measured at very low head. | Compare flow at your actual discharge height and hose or pipe setup—not maximum-flow figures alone. |
| Maximum head | Maximum vertical water lift, typically given in feet or metres. Total dynamic head also includes losses from fittings, valves, and pipe friction. | A pump near its maximum head may deliver little or no useful flow. For reference, 1 psi of water pressure is approximately 2.31 feet (0.70 metres) of water head. | Allow headroom above the measured lift and check the pump curve at that operating point. |
| Solids-handling capacity | The manufacturer’s stated maximum particle-passage diameter, plus any restrictions on the type of debris. | Leaves, grit, and other debris can block an inlet or impeller. Clear-water pumps are not designed for the same debris load as pumps intended for dirty water. | Choose a model rated for the water condition; do not infer solids capacity from flow rate or outlet size. |
| Minimum water level and drawdown | Minimum operating depth and the residual water level the pump can leave on a flat surface. | Many standard submersible pumps need water around the motor for cooling and may stop before a floor or pit is completely dry. | For shallow-water cleanup, verify the specified drawdown depth and whether manual operation is required. |
| Switch and automatic operation | Float-switch or other automatic-control type, activation level, shutoff level, and required clearance around the switch. | The switch controls when pumping starts and stops. A restricted pit can prevent a float from moving freely. | Check pit dimensions and operating levels; consider a suitable alternative control where float movement is obstructed. |
| Motor protection and duty rating | Thermal overload protection, permitted operating conditions, and whether the pump is rated for continuous or intermittent use. | Overheating, dry running, or operation outside the stated duty can shorten motor life or cause failure. | Match the duty rating to the expected run time and follow the installation and cooling instructions. |
| Materials and water compatibility | Pump-body, impeller, seal, and fastener materials; confirm any limits on water temperature or chemical exposure. | Material suitability affects corrosion resistance and service life. A general drainage pump may not be suitable for corrosive or chemically contaminated water. | Use only within the fluid and temperature limits stated in the product documentation. |
| Power, cable, and outlet connection | Supply voltage and frequency, rated electrical input, cable length, outlet size, and compatible hose or pipe fittings. | Electrical compatibility and a suitable discharge connection are essential for safe installation and expected performance. | Confirm the local electrical supply and connection requirements; use electrical protection appropriate for wet locations. |