You may find roots or just a simple blockage.

We attempt to evaluate drainpipes by flushing every drain that has an active fixture whileobserving its draw and watching for blockages or slow drains,but this is not a conclusive test and only a video-scan of themain line would confirm its actual condition.

Make sure your tenant isn’t using flushable wipes, they can lead to pipe blockages. 

Short of some sort of lock-out, or physical blockage of occupancy, I am struggling to come up with any alternatives and thought I'd tap into the community's collective wisdom.Thank-you in advance.   

I am getting it scoped tomorrow to see where the blockage is exactly but we think it is probably a root ball in the pipe (caused by nearby tree).

Does anyone have experience leaving blockages up past the permit date?

I hired a sewage guy last Saturday personally and he found three full blockages (He snaked most of the 160 feet of the line).

After the blockage was cleared, the basement drained out but was left with the very pleasant smell and residue of sewage all over.

It will work for a complete blockage, but to clear the buildup of soap and grease, you need a drain clearing product to break down that mess.Zep has a product called Drain Care.

Upon receiving the sellers disclosure, I learned that the basement flooded (3 in of water) thanks to city pipes backing up from root blockage about a year ago.