Why can a suction pump lift water only about 10 metres?

A suction pump operates by creating a partial vacuum within its cylinder. This vacuum allows atmospheric pressure acting on the surface of the water source to push the liquid up into the pump.1

Because this process relies entirely on the weight of the atmosphere to move the water, it is limited by the maximum pressure the atmosphere can exert. Consequently, a suction pump can only lift water to a height of approximately 10 metres (34 feet). To move water from greater depths, engineers utilize a force pump, which uses the mechanical force applied to a piston to push water to higher elevations regardless of atmospheric limits.1