Property management of leaking sewer pipes in toilets?

Under normal circumstances, because sewers are public pipes, they should be maintained by residential properties and should be maintained within the scope of maintenance. However, if it is man-made, such as 1, and the pipeline leaks due to improper use by the upstairs owner, the upstairs owner shall bear the responsibility. 2. If the pipeline leaks due to the renovation of the downstairs owner, the downstairs owner shall bear the responsibility.