Wrapping up the Plumbing woes..., the Master of the house arranged for the septic service to come out and look at the tanks. Naturally, they were nowhere near full and didn't need to be pumped out. However, we did get dinged for a service call (which was as much as pumping would have been).
The next stop in our plumbing journey was to call a plumber to find the clog. So, I stayed home to supervise the service call. (Which was also as much as pumping the septic tank would've been.)
The cause? A hard bend from the toilet to the main pipe and too much Charmin! We have since made a new house rule for the person using that bathroom that "if it doesn't come from your body, don't put it in the potty!"
As luck would have it, my landlord arrived with his plumber, while the plumber I hired was finishing his work. My estimation of my landlord's plumber is definitely on the low-side.
I don't know where he found this guy (apparently, a number of other folks have found him too since he said his schedule is full for at least a month). I do hope he is getting a rock-bottom price though because his expertise leaves something to be desired.
His solution to the current plumbing situation was to clean out the main pipe. It took me 4 explanations of why that was not the optimal answer before I finally got the point across to the landlord and he decided that my suggestion is in fact the best long-term solution.
As I explained to my landlord (and his plumber), the current issue has been fixed. What I am interested in solving is what caused this to happen like it did in the first place.
It just isn't a good idea to have a toilet empty to a main pipe at less than a 5% grade and is only 15-20 feet long. It means that anytime there is a clog in the main pipe you run the risk of black water backing up into all of the sinks, bathtub(s), and appliances.
One would think a landlord who is interested in maximizing his profit on a rental property would immediately grasp that the immediate investment will save emergency expenditures later. Thankfully, I was able to get that across to him and now we simply await the scheduling of plumbing work.
Watch, it will be scheduled around the same time as a fabulous snowstorm this winter...