A water purifying system includes a base having a storage tank removably connected thereto and purifying device is connected to the storage tank so as to provide purified water into the storage tank. A pumping device pumps the purified water in the storage tank to a faucet. A high level detection unit is located in the storage tank and a low level device is connected to a pipe connected between the storage tank and the pump. The high level detection unit controls the pump to pump the purified water into the storage tank, and the low level detection unit stop the operation of the pump when no water is left in the storage tank so as to protect the pump.