Contact the plumber and find out where the blockage was found in the system.

The only time I could see it being charged to the tenant is if they caused a blockage or if the system is filling up unnecessarily fast.

I recently had a simple drain blockage and called Roto Rooter.

As it was, though, we thought it a much better idea to try the simple solutions ourselves first, in case they worked, before calling in the experts when the average main sewer blockage repair bill was anywhere from $400 to $900, depending on the website researched, and I doubt that includes the cost of clean-up of the crud after the repair, in any case.  

The plumber was called in and removed the blockage and the restoration company has provided fans, dehumidifiers, and microbial compound to kill the bacteria associated with the overflowing fluids.My downstairs floor is laminate wood flooring.

It would turn "open" at times and turn "closed" at times, thus causing the intermittent blockage.

I had another guy come scope it for a second opinion and he said he jetted it, got through any major blockage and it should be fine.

There also could be blockage in your sewer line.  

Our plumber does give us a description of the blockage or issue and we screen this for tenant responsibility- ie superman was snaked out of the toilet, cat litter was dumped out of the now unusable garbage disposal (also interesting in non pet friendly properties) and we will pass that charge on to the tenant with appropriate explanation. 

I have a house that had problems with unruly roots which caused some plumbing blockages.