It was just one young woman living there and she swore she wasn't flushing anything irregular.  

@Michael Slabitcher I'm also from Flushing, NY.

Install cabinets.Installing ceiling fan light.Install dome/flush light.New faucet, install faucet.Carpet (lowes whole house install).

Small leaks can add over time such as toilets etc. i had some bills almost double from usual , back to normal after redoing most of the flush mechanism.

But if the same condition was caused by a tenant who flushed inappropriate items down the toilet, then the tenant pays.

The toilets overflowing because you flushed too much paper?

People flush certain "things" down that have a tendency to clog the drain field up - they won't care nearly as much as if it was your primary residence.  

He taught himself all of the programs that he uses to draw plans and renderings, in just a few months, plus goes to the City Planning and Building Departments to flush out what he needs to get the job done.However; he has been on jobs and in meetings since he was a baby.

We ended up making a little money and had enough cash flow throughout to be relatively  flush. 

I would make sure that you have quality toilets that flush good.