Portable water and energy saving bathtub

A portable water and energy saving bathtub comprising:

• a body, it is defined by a first and a second side walls, a first and a second end walls as well as a bottom to become an opened container without a water discharge hole, a step on the bottom is located beside the second end wall;
• a flashboard gate, which is the first end wall, includes a groove on inner faces of the container, a flashboard capable of moving is inserted into the groove, a water seal ring is set between the groove and the flashboard, when the flashboard gate is closed the container holds water without, when the flashboard is opened water is discharged;
• a reducing-volume-chunk for raising water level in the bathtub, liking a cube, a width of the cube is smaller than the same of the container, a height of the cube is smaller than a distance between legs of a bath person sitting on the step and a top of the container;
• the reducing-volume-chunk has two hanging arms extending to outside of the cube, each hanging arm has a groove, the grooves sit on the first and second side walls of the container, therefore, the reducing-volume-chunk is hanged in the container;
• a locking-releasing-device for the reducing-volume-chunk, which can lock the reducing-volume-chunk together with the container or release the lock to separate the reducing-volume-chunk from the container.