[Original 1931 text] "The Great Bath, which I have reserved to the last, was part of what appears to have been a vast hydropathic establishment and the most imposing of all the remains unearthed at Mohenjo-daro." (Marshall, Vol. I, p. 24)
The Great Bath at Mohenjo-daro related images.
No "Great Bath" like that in Mohenjo-daro has been found in Harappa, and it is not known if one existed among the miles of ruins carted off for railway construction in the early 1850's.
This drain cuts through the edge of the so-called granary. If the entire drain were constructed along with the Great Bath, this feature would indicate that the original "granary" was built before the great bath.
The floor slopes down to the southwest corner where a small outlet (top right) leads to a brick drain, which takes the water to the edge of the mound.
At the southwestern corner of the sloping floor, a small drain first passes through the massive walls of the tank and connects to a corbelled arch drain that curves along the edge of the northern terrace of the granary to the west.
The tank would have been open to the sky, but the surrounding structures would have been roofed. The sidewalls and parts of the floor have been conserved using modern replica bricks.
The side walls of the tank were constructed with finely fitted bricks and a thick layer of bitumen (natural tar) was laid along the sides of the tank to keep water from seeping through the walls and up into the superstructure.