To provide a low tank for preventing decrease of a water storage capacity of the tank by eliminating an overflow pipe.

The low tank is provided with a water inlet 3 for feeding water to a tank 2 and a water outlet 4 for discharging water to a toilet stool. A feed water valve 5 for opening and closing the water inlet 3 is provided in the water inlet 3. A drain valve 6 for opening and closing the water outlet 4 is provided in the water outlet 4. An operation part 8 capable of opening the drain valve 6 through an operation coupling means 12 is provided in the tank 2. A ball tap 9 fluctuating by change of a water level of the inside of the tank 2 and opening and closing a feed water valve 5 is provided in the tank 2. The ball tap 9 is set so that the feed water valve 5 is open in a state not exceeding a prescribed water lever and is close in a state exceeding the prescribed water level. A coupling member 11 coupling the ball tap 9 and the drain valve 6 is provided so that the drain valve 6 is opened by lifting of the ball tap 9 in the state that a water level in the tank 2 is higher than the prescribed water level.