Thanks for your reply. A plumber will be my last resort as I live in a rural area and a good one is hard to find. The 50' auger that we used was an electric powered unit that was rented from Home Depot. The associate told us it was the one to use on roof vents because it is weighs less and is safe to place on the roof.

This is a single level home on a concrete slab and was built in the late 60s and I have no idea how the plumbing is actually laid out. I've lived in this house for 10 years and have never had any plumbing issues until now.

The 2 bathrooms are on one end of the house. The kitchen, laundry room, and half bath are on the opposite end and are in proper working order. No problems whatsoever.

One clean out is available. It is on the corner of the house by the bathrooms and is on same side as the Master Bath. It has been checked by city sewer person and we were told it is clear all the way out to the road.

Thanks

You are basicly saying "teach me how to snake a sewer line". Do you realize plumbers teach assistants by showing them? Do you realize pros often need to walk all the way around a house to figure out how to approach clearing a drain? Do you realize that machines large enough for 4" lines are much too heavy for average men to carry up a ladder onto a roof? Do you realize large sewer augers are dangerous? More than a few got broken arms and/or living daylights slaped out of them when a power snake hung and threw a loop in snake between machine and cleanout (which they routinely do). There are things in life (like driving cars) that are better left to the experienced individuals until proper training is undertaken. If you still feel you must push forward,rent a machine with 3/4tr cable and put it down toilet where wax was replaced (yes I know,but that's another place where experience pays). Have a helper run water while you operate snake. If water starts rising up toilet line ask helper to slow down or stop before flooding floor. When helper is unable to flood toilet line you have cleared the line.

No I'm not asking to be taught how to snake a line! I am working with someone who knows how to snake a line and we are still working on this issue as I am typing. I am asking for help regarding where the possible blockage might be as we have not found it yet. Thanks...

Question: Are you saying to snake the toilet even though the tub is where the water is backing up?

I'd run a hose, at full blast, into the clean-out. If water backs up, as I suspect it will, you have a blockage in the horizontal main drain, somewhere between the two ends of the house. This assumes that the Master Bath and Guest Bath tie into the main drain separately. If, instead, the baths tie together before going to the main, then the blockage could be in that section. Klem's recommended procedure should work either way, though you might want to snake from the clean-out first as it makes for less of a mess inside.

Also, check your vent pipe. It's probably on the roof. Some go out through walls, and some have them on the ends of pipes usually near the fixtures.

" I am working with someone who knows how to snake a line "

Grace I don't intend to disparage you nor your help but your questions clearly show that is just not true. I misspoke,snake go's down line beneath toilet after toilet has been removed,not into toilet. Other than that, what I told you is accurate. I've done the job many times.When seeking advice you shouldn't counter answers unless you have knowledge to the contrary.

Yes I understand that the toilet has to be removed first

This is a great forum and thanks to all who have been so understanding, courteous and helpful. We located the blockage and it is in the main drain line that ties into the city sewer system. Thanks again!

"We located the blockage and it is in the main drain line that ties into the city sewer system. "

I guess that means "city sewer person" was blowing smoke right from the begaining.