So it is possible the blockage was originally caused by someone next door, a blockage formed downstream of the wye, but since it's vacant, no one sent anything down the drain to trigger any symptoms. 

one issue is if you bought 30k properties they are probably fairly old and will constantly need up keep could be a symptom of the asset its self.

Thus, I feel like my heavy cough symptoms, and inability to run/exercise for long period may be due to mold issues stemming from this roof.  

Bottom line , shutting the system off and waiting may have temporarily treated a symptom but would not have fixed the problem.

@Matthew Paul and @Joe Splitrock, my classic symptom of a toy, or an ink pen, or a similar object in the toilet is a slow flush or no flush (for a while) until the clogged toilet paper wrapped and bunched up around the object dissolves. 

If you suffer from PTSD, anxiety, depression, or are generally unable to handle difficulties in life, please don't read any further.Emotional Support Animals are merely a symptom of an ever-weakening society.

@Lucas Carl The only tenant I ever had that rose to that level of crazy was NPD (narcissistic personality disorder); he actually told me that-- and I believe it because he had all the symptoms.

He shows very few symptoms and is very active.

The common symptoms here are water backing up from the bathtub, toilet and sinks in the garden unit.

It was the final symptom of an over the top complainer who was with my 3 years.