Analysis study was done to explain the effect of the longitudinal section on the values of pressure of the water hammer resulting from the trip of pumps, which results a low pressure wave often lead to get cavitation, has been shown from the analytical study of several profiles and compare the results, that the shape of the profile and the level of the pressure line after the stopping of pumps determines the type of cavitation formed , the region in which it occurs and the pressure values resulting from it, when the profile doesn’t contain bends or the bends are below the level of line pressure a distributed cavitation is occurred, In the case of the presence of high points , the effect of the bend is linked to several factors: 1 - the greater the height of the bend above line pressure increases the possibility for column separation and increases the pressure forces. 2 –the pressure forces increase whenever the bend closer to the pumps.