We are a small association of 9 buildings of twin homes that have a shared main sewer drain, which is pvc. In November the association had all of the main lines cleaned as a matter of maintenance which had not been done for at least 10 years. No drains were found to be clogged or slow. Now, in May, an owner called to say she and her neighbor had a backup. This happened while she had a great deal of company. I suspect one her guests or their children overloaded the toilet which caused a clog in the line and then backup to the neighbor but have no way to prove it. Now the owner with the company, as well as the lady who was home alone, want the association to pay for the sewer cleaning bill. I don't see how pvc lines could become clogged in 6 months unless there was a "user" problem. Should the owners or association pay the sewer cleaning bill? No one has indicated thus far that there was any damage to claim.