What is a common maintenance task for pumps in a water system?

Greasing bearings to ensure smooth operation is essential in the maintenance of pumps in a water system. Bearings allow the pump's rotating parts to move efficiently and with minimal friction. Over time, lubrication can degrade or diminish, leading to increased resistance, overheating, and potential failure of the pump. Regular greasing ensures that the components operate smoothly, extending the pump's lifespan and maintaining operational efficiency. This task is part of routine maintenance that helps prevent more significant issues that could arise from neglecting lubrication.

The other options involve actions that are not standard practices for regular pump maintenance. For instance, replacing the entire pump is typically only necessary when the pump is beyond repair or has reached the end of its useful life. Adjusting the pump size periodically is not usually a maintenance task; this is a design consideration that would be addressed during installation. Changing the color of the pump for visibility does not contribute to its functionality or maintenance and is more about aesthetics than operational integrity.