New condo with clogged sewer line.  Who is responsible?

We bought a condo and had it inspected first, but the inspection did not find the sewer problems that we began to experience almost immediately upon moving in. There are blockages in the sewer line that have caused the system to back up and then to cause damage to the ceiling of the unit below. Apparently, someone put wipes or diapers in the system before we bought the condo; the wipes/diapers expanded once we started using the system (the condo had been vacant for a long period before we moved in). What liability do we have, and is there some solution other than for us to be stuck with thousands of dollars for remediation and repairs of the apartment below us?  Baltimore Maryland