Which type of pump is designed so the entire pump and motor unit can be placed below the water level in a well?

A submersible pump is specifically designed to be fully submerged in water, making it ideal for applications such as wells. These pumps are constructed to operate underwater, which allows them to push water to the surface rather than relying on suction, as is the case with other types of pumps.

The design of a submersible pump includes a hermetically sealed motor that prevents water from entering and causing damage, thus ensuring reliable operation when installed below the water level. This setup can effectively handle high-pressure conditions that would be encountered while pumping water from significant depths.

In contrast, other types of pumps, such as jet pumps and centrifugal pumps, are typically mounted above the water level and require different mechanisms to draw water up. Jet pumps create a vacuum to pull water into them, while centrifugal pumps can only function efficiently when they are above the water, relying on gravity and air pressure to create flow. Mixed-flow pumps, meanwhile, combine features of both axial and centrifugal pumps but are also not designed to operate entirely submerged in water like submersible pumps.