The cities of the Indus Valley civilisation were built from kiln-fired bricks of a consistent proportion (roughly 1:2:4) used across hundreds of kilometres, an early instance of building standardisation at civilisational scale. Streets carried covered brick drains fed by household bathing platforms and latrines, with manholes and soak-pits for maintenance, while the Great Bath at Mohenjo-daro shows watertight brick-and-bitumen construction. This combination of dimensional standardisation and city-wide waste removal predates comparable systems elsewhere by millennia. It treated sanitation and supply as a planned municipal infrastructure rather than a private matter.
It represents the earliest known fusion of standardised building components with a planned, city-scale sanitation system, foundational to dense urban living. The Indus achievement set a benchmark for public health infrastructure that would not be matched until the modern era.