Children living in the building must know that the kitchen and bathroom are equipped with relatively thick sewer pipes. This one
This thick pipe goes all the way to the sewer and then through the roof.
This is because there is not only waste water but also air in the sewer. If the air has no way out,
It will block the sewer. The downward flow of waste water will push the air upward and let it flow to the roof.
When it enters the atmosphere, the wastewater will flow into the sewer smoothly.