Which of the following is a cause for noisy pumps?

• A. Normal Operation
• B. Not Primed
• C. Regular Maintenance
• D. Adequate Lubrication

Answer: (B)

Not primed means the pump isn’t filled with liquid, so air is drawn into the pump instead of wastewater. The impeller then tries to move air, which cavitates—air bubbles collapse inside the pump—causing loud banging or whistling and general noisy operation. This noise is a telltale sign that the suction side isn’t properly primed and the pump is not delivering liquid.

Normal operation should produce the expected, smoother sound of moving liquid. Regular maintenance and adequate lubrication help reduce noise by addressing wear and friction, not by causing it, so they aren’t the source of the issue in this case.