The waterhammer occur when the pumps are started or stopped for the operation or tripped due to the power failure, and the hydraulic transients take place as a result of the sudden change in velocity. Several times, the field tests of the waterhammer were carried out for Pangyo booster pumping station. Pangyo pumping station was installed with the booster pumps of 6 sets and the in-line pumps of 2 sets. The in-line pumps are additionally needed to the surge suppression device so that the pumping station acquire the safety and reliability for the pressure surge.