Monday morning this week I was informed to "hold it in" and postpone any washing, if I had that planned.
From noon the water was cut off and the old pipes were removed and replaced with new PVC pipes.
I left the house from 11:00 and returned around 17:00 and the work was done.
New pipes for the sewage included the main pipe (see the pictures below) serving the bathrooms inside the attic and first floor apartments and the groundfloor kitchen.

Addtionally new underground drains were installed in the courtyard to prevent water from accumulating and flooding the terrasses and the AC return drainage from the house units.

Most importantly, the new pipes for the masterbedroom toilet and the masterbathroom were installed and connected to the secondary sewage pipe junction in the courtyard.

From the first floor exterior, the outdoor bathroom and the canopy drainage were connected to the new sewage pipes in the yard.