I am trying to identify the reason for a drain vent in an area of my house with no other plumbing. The house only has 1 bathroom and a kitchen sink. The kitchen sink drains into a grease trap and has a 1.5" vent. The bathroom has a separate drain that meet somewhere in the backyard and has a 2" vent. Then there is a third vent that enters the foundation in an area where there is no other plumbing. Here is a photo of the vent and where it is located in the house:
I have spent the past few days ripping all the rotten drywall out of the house and can say with confidence that nobody ever updated the plumbing in this house with any kind of long term view. Any help is greatly appreciated.
Best Answer
Given the "cast iron transitions to plastic" (or at least "new and older piping connect") it would appear that the toilet was moved, and the vent was preserved.