Living in the building might make it easier...or it might be even more intrusive to have tenants knocking on your door to ask how to work the dishwasher, ask where the bean is, tell you the toilet is clogged, etc.etc.etc. and you are constantly worried about the cranky people leaving bad reviews, which definitely affect revenue. 

@Brian S.I don't mean to be intrusive, but what is the end game on this deal?

"Oh but that's INTRUSIVE or CREEPY....NO tenant will allow THAT!" 

You did the right thing and I wouldn't give her anything for that minor intrusion.

The City official will never step foot onto your property but they will clear the line just outside your property, which is where, for the most part, the problem lies: ROOT INTRUSION!  

@Ley Nezifort Hi Ley, I would certainly keep an eye out for dry rot and water intrusion on the exterior, just like you would on a smaller property.

During the hydrojet call, the technician snaked the line and suspected there was an obstruction about 50-75 feet in, so I think a fourth possibility is roots intrusion.

I recall one lady in NY just whining up a storm becasue her gutters had leaves in them which caused some issues with water intrusion.. and boy she was all over her PM.. like the PM can go out weekly and check for leaves in the gutters  LOL

Anything more frequent than that will start to feel intrusive to your tenants.

However, they conducted an intrusive and potentially harmful test to my plumbing system without my consent which violates the terms  of the sales agreement.