The water available to a centrifugal pump must always be what?

For a centrifugal pump to operate effectively, the water must be under pressure to ensure that it can flow smoothly into the pump's intake. When water is under pressure, it prevents the occurrence of cavitation, which can cause damage to the pump impeller and reduce its efficiency.

Maintaining a certain level of pressure ensures that the pump can generate the necessary force to move water through the system. If the water were not under pressure, the pump might struggle to draw in the fluid, resulting in inadequate flow and potential operational failures.

While factors like contaminants and temperature can affect the quality of the water and the overall performance of the sprinkler system, the immediate and critical requirement for a centrifugal pump is that the water must be under pressure to facilitate proper operation.