The pulsator clarifiers is very sensitive about the changing of the water quantity. So the most important part of pulsator clarifiers is the perforated pipe for to drain the raw water with equal pressure and velocity. First, we evaluated the design parameters of the common perforated pipe. The uniformity of outflow from the perforated pipe is directly affected according to area ratio. In other words, the uniformity of outflow is improved as area ratio is smaller. Also, at the same area ratio, the uniformity of outflow is improved as number of holes is increase. Specially, in case of the two holes per length of pipe diameter(2/D) shows the most uniformity of outflow and the best hydraulic with the smaller pressure drop. Second, we evaluated the pulsator clarifiers that has installed and operated in H water treatment plant. Results, it was designed properly that the ratio of cross section between pipe and holes is 8.9%. But the distance of each holes should be improved to 2/D of the optimal value from 1.3/D. The standard deviation of distributed quantity from the middle channel to the hole pipe was 0.12 and from the hole pipe to holes was 0.04.