I've seen a bunch of old pipes (clay and cast iron especially) that over time, when new roots grow in and around the pipes, they get pushed up and out of proper grade, causing pools like you're getting. If it was a blockage, it probably would have backed up a lot farther now. Fortunately for you, since the pipe is 50" below grade, you've still got plenty of "slope" from the lowest drain in your house to the street.

There's a couple of things you could do to get the water out of there. See if you have a cleanout in the lawn somewhere that would give you access to the sewer pipe (between the backflow and the street). If there's not one, dig up the pipe and have a plumber put one on, it's not to big of a deal unless it's clay, in which case by this point you'd probably need it replaced anyways. Anyways, now that you've got a cleanout up at grade level, get yourself one of these: (see attached photo)

Basically, you shove that down into the pipe and inflate it, so it blocks off the flow of poowater coming back into the house. Then you can vacuum out the water where you're working. They make extensions for the chain and the schrader valve to inflate it with if you're working down a long standpipe. They can be found at any plumbing supply store.



If you're lucky, you could try to cram the test ball in one side of the backflow, but I imagine it would probably obstruct your work.

Or you could get some long, rubber gloves and go at it by feel. ew.

Attached Images

7799.jpg (10.6 KB, 3 views)