Many buildings use a local underground in order to dispose of the waste water used there. Mostly untreated, this waste water is filtered as it percolates into groundwater. Immersive Reader river system

recharge zone

saturation zone

septic system

they had the law tat factories that produces smoke cannot be built near residential buildings.

building of proper sewage system was done to ensure that the waste is carried away from the humans so that they do not get diseases from it.

also they built water systems to provide water in those areas which are drought prone.

this might