PURPOSE: To obtain a small scale and separate water receive tank from which water can be manually gotten in an emergency, by providing an inflow pipe, an outflow pipe, and an air plug in a container airtightly closed.

CONSTITUTION: An outflow pipe 3 having an intake opening 13 extended to the level near the bottom 12 of a water tank, an inflow pipe 2, and an air plug 4 are provided in the upper cover 11 of an airtightly closed container 1. Only at the first time, the plug 4 is opened and while discharging the inside residual air of the container, water is fed therein from the inflow pipe 2 and then when the water level reaches the upper cover 11, the plug 4 is closed. From the next time, when a specified faucet 15 is usually opened, a certain volume of water is always secured. In an emergency, a cut-off valve 14 is closed and an air pump for bicycles is fitted to the plug 4 and actuated to feed air with pressure. In this way, the water level is pushed down and the water in the container is discharged to the outside through the outflow pipe 3.