Cavitation, represents one of the most important limitations of all types of hydraulic machinery so as to automotive water pump, is the result of a reduction of the local pressure in a disturbed or flowing liquid to a level at, or near to, its vapor pressure. This paper focused on the criterion for the generation and prevention the cavitation for automotive water pumps. The test was performed on a water pump motoring rig and mixture of 50% antifreeze, ethylene glycol, with 50% water were used for the coolant. The test was carried out for various system pressure and for various coolant temperature which were controlled. The present study shows that the cavitation of water pump is strongly depending on the vapor pressure of the coolant and coolant temperature as well. It has been proved that for above a certain value of system pressure, surge tank pressure there were no cavitation for all tested water pumps and the influence of cavitation for efficiency, flow-rate of water pump was investigated as well.