Which type of pump uses a rotating mechanism to move water?

A centrifugal pump uses a rotating mechanism to move water, making it an effective choice for transporting large volumes of liquid. The design of the pump typically consists of a rotor or impeller that spins within a casing, creating a centrifugal force. This force pushes the water outwards from the center of the pump, increasing its velocity and pressure as it exits through the discharge pipe.

Centrifugal pumps are widely used because they are efficient for applications that require consistent flow rates and low viscosity fluids, making them ideal for various surface water applications. The simplicity of their construction also contributes to ease of maintenance and operation, which is another factor that enhances their popularity.

In contrast, the other types of pumps mentioned operate on different principles. Piston pumps use a reciprocating motion to move water, and a step pump typically denotes a specific type of mechanical movement not directly related to rotating mechanisms. Peristaltic pumps convey fluids through a hose or tube by squeezing it, which is also not based on rotation but rather on the motion of rollers or shoes compressing the tubing. Thus, the centrifugal pump stands out as the correct answer due to its reliance on rotation to effectively move water.