(i) The great bath was a large, rectangular tank in a courtyard. It may be the earliest example of a water-proof structure.
(ii) The bath was lined with bricks, coated with plaster and made water-tight using layers of natural bitumen.
(iii) There were steps on the north and south leading into the tank.
(iv) There were rooms on three sides.
(v) Water was drawn from the well, located in the courtyard and drained out after use.

(i) They had well covered drains.The drains were covered with slabs or bricks.
(ii) Each drain had a gentle slope so that water could flow.
(iii) Manholes were provided at regular intervals to clear the drains.
(iv) House drains passed below many lanes before finally emptying into the main : drains.
(v) Every house had its own soak pit, which collected all the sediments and allowed only the water to flow into the street drain.

Indus Civilisation is called urban civilisation because
(i) There was well-conceived town planning.
(ii) Astonishing masonry and architecture were found.
(iii) Priority was given for hygiene and public health.
(iv) They used Standardised weights and measures.
(v) They had solid agricultural and artisanal base.

Indus, civilisation is called Bronze Age civilisation because it is a historical period characterised by the use of articles made of bronze.

(i) Literary sources
(ii) Aerial photographs
(iii) Magnetic scanner
(iv) RADAR 
(v) Remote sensing methods.