PURPOSE: To make it possible to detect the presence of water leakage, and what is more, to detect the amount of water leakage per leakage time in the case of water leakage in an elevated tank type water supply device which uses a storage pump.

CONSTITUTION: In an elevated type water supply tank, an operation status of a motor 5 of a storage pump 4 is recorded with a recording means 20 every time when the pump motor 5 is operated. The recording means 20 displays its operating result by way of a timer 16 within a specified time late at night. The recording means 20 is installed at a remote site while an operation signal of the pump motor 5 is transmitted to the recording means 2 by using a telephone line 17. In addition to that, an intermediate water level detector 13, which is operable only for a specified time late at night, is installed to a spot at a position slightly lower than that of a high water level detector installed in the elevated water tank 7 so that the pump motor 5 may be operated every time a detection signal is transmitted from the intermediate water level detector 13.