Who pays for repairing the plumbing in the building
Question
Hello.
If there is a blockage in the main pipe on one side of the building, how are the repair expenses divided?
Answer
Shalom u-vracha (hello and blessings).
If there is no different custom in the building (or in the neighborhood, etc.), only that side pays.
Source
In siman 164 it is explained that, as a matter of strict law, the owner of the house and the owner of the upper story are partners, and each is obligated to repair his section insofar as it affects the stability of the building, and not according to who suffered the damage. Nowadays, however, the building is jointly owned, and in some places there is a custom and/or stipulation that everyone must participate in repairing damage that is not private. Nevertheless, in a place where there is no such custom, the repair falls upon the side to which that line belongs (meaning that in terms of ownership the piping belongs to everyone, but in terms of utility it benefits only one side, and therefore that side must repair it).