I live in a fairly new apartment built above an old garage/storage building. When I shower upstairs the downstairs toilet as well as a pipe coming out of the floor beheath the stairs, both fill and spill over. The building is on a septic system, and the water does smell like sewage. Any help would be much appreciated. The pipe coming out of the floor has a hose draining into it, and a hand towl jammed in it to keep it from leaking? I had never noticed the pipe until now. When I pulled the towel out water spilled out very quickly.

You have a partial blockage in the drain line to the septic tank. Snake the line from the point where the hose is connected. Properly seal the drain line and the connection of the hose.

Call your landlord, it is their problem.

I agree with the experts, You have a blockage that must be addressed. Will the landlord pick up the job or is it on you? If so we can help.

as well as a pipe coming out of the floor beheath the stairs,Tell me more about this pipe. Is it trapped and vented? A old washer set up? Any smell from it? Back to you, Tom

My "landlord" is my grandfather, he is not familiar with the plumbing in the building at all. So the problem is on me to get taken care of. I cannot trace the hose into the pipe back to the source, it runs up under the stairs into the brick wall. Here is a terrible photo, probably no help at all.

In general, no smell coming from the pipe. After my girlfriend took a shower and there was slow leaking from it, I pull the towel out and the water that came out smelled like sewage.

imgur: the simple image sharer (http://imgur.com/uS6LQZo)

Well, pull the towel and hose out and run a drain snake down the pipe.