[throw_away_elec]

>> "Among other things, they contain the world's earliest known system of flush toilets." [1]

>> "With a number of courtyard houses having both a washing platform and a dedicated toilet / waste disposal hole. The toilet holes would be flushed by emptying a jar of water, drawn from the house's central well, through a clay brick pipe and into a shared brick drain" [1]

Amazing. This was about the Indus Valley Civilization in 3300–1300 BCE.

It's interesting to note that how much a civilization, like Rome after the collapse as shown in the below thread, can lose much of cultural or technical advances it made earlier.

[1] https://en.wikipedia.org/wiki/Sanitation_of_the_Indus_Valley...