Undisclosed sewer defect! Seeking advice!

[Sandy Hu]

I just purchased a property and realized there is an undisclosed sewer defect. The property was previously managed by a management company. According to the plumbing company, the property manager was aware of the defect, but they are not sure if the owner knew the situation. However the property manager and the listing agent belongs to the same company, I highly doubt neither the owner nor the agent knew the defect.

Any advice on how to deal with the situation is appreciated!