Sometimes C class tenants drain you and your wallet when dealing with them, other times you end up with a cheap property and a long term tenant that works out great.

You'll give up about 1-2k max per year but free yourself up from all the emotional drain.

A lot of utility companies offer supplemental policies for delivery and drain lines - you could ask them along with the 3rd party carrier mentioned in the comments above.

They even poured concrete in the toilet and shower drain. 

Camera the sewer/drain lines.

If you just blindly establish a LLC, thinking it's serving a "purpose" because hearsay but it's actually not, then you are just throwing time and money down the drain for no reason. 

Both are more often than not the result of a plugged drain or stuck timer.The rest of the advice here is great!

It's most likely caught in the drain trap of the toilet. 

Looking for some insight for a situation, primarily curious how others would handle.Had a guest contact us requesting someone to look at the drain on the tub/shower because even after a couple hours it wouldn’t drain. 

The inspection isn't very hard, make sure the plugs are grounded, the hot water works, the toilets flush, drains work and light switches work.