A submersible pump is one that has to be immersed in water, and is normally used to drain water.  These pumps are used in situations that involve flooding, such as rising groundwater in cellars or basements, flooded boats, or flooded areas.

Submersible pumps come in different models, and they distinguish themselves mainly in terms of the water that needs to be pumped, for example, clean-water submersible pumps,  which are used for rainwater. Other models are dirty-water or wastewater submersible pumps that are able to process water that contains sand, soil, and residue, or heavy-duty models that can process even coarser materials such as large solid particles. The impeller at the bottom of the pump processes solid particles by cutting them up so that they can be easily drained.

Submersible pumps are supplied with or without a float, though a float is handy if the pump needs to switch on or off automatically. If a space has to be drained completely dry, this will need to be done manually. The pump has to be switched off in time to prevent it from running dry. Some models are fitted with both a manual and an automatic mode (float switch).