This paper is performed to find out the stability of water-hammer in pipe line and pump station that is happened when additional water needs demanded. At first, the water supply construction project is planned to supply $6,000;m^3/day$ through 17.9 km pipe line. But additional demand ($1,200;m^3/day$) happened from Cheong-ra water reservoir. In this situation, air-chamber($4;m^3$) and vacuum breaker valve(${varphi}100;mm$) are needed to prevent water-hammer. When the additional water is supplied, the existing facilities (air-chamber, vacuum breaker valve) are sufficient to alleviate shock not changing capacity alteration, judging from the airspace change and rise. Therefore, there is no problem for water-hammer by installing air-chamber($4;m^3$) and vacuum breaker valve(${varphi}100;mm$) at the top of Yeo-ju hill.