My wife and I recently purchased a home; a 3 story colonial built in 1920 and measuring appx 20'W X 50'L. It has lots of problems, most of which we are tackling as best we can. However, we are stumped as to why the plumbing system has drainage problems leaving the house to the city sewer system. About every month, we have to open the 3" clean out and snake the sewer line to get some relief from waste water seeping out of drain lines and pooling in the basement. We already suspect that when they upgraded some of the plumbing lines from, what appears to be, galvanized steel to PVC they(the previous owner/contractors who bought it to fix up/modernize to flip it) may have damaged some of the existing piping. However, we noted tonight that there is a covered, unsealed tank(box) of some sort located at the front of the house just past a 3" vent pipe that comes up out of the floor and bends 90deg to exit the front of the house and, I guess, "breathe" under the front porch. This tank(box) is filled with waste waste/sewage. It isn't overflowing into the basement and never has in the 4 months we have lived here. But the basement has always smelled and we, stupidly, chalked it up to just being an old house with left over stench from the few times we didn't snake in a timely fashion and we had some seepage. After finding this tank(box), we tried a few methods to understand why and how waste water/sewage is making its way to this tank(box) and we are at a loss as to what it even is. All my research online tonight indicates it is a cesspool/sink sump of some sort, but why it would be inside the building structure is unfathomable. I have no idea what this tank(box) is and am at a loss as to what to do with it other than to just pump it out(though I don't know where to put this waste water since my block doesn't even have storm drains) and visually inspect it to try figuring it out with it empty. My wife tried scooping it with a snow shovel in an attempt to clear openings for inlet/outlet that may be blocking flow. When we snake the 3" clean out, we can get the snake to travel appx 24', which is just about how far from the clean out access is from this tank(box). We don't know what to do other than call a professional plumber, but I feel kind of foolish doing that after we have done so much to just be stymied by not knowing what this stupid component is. I intend to call the twp in the morning to confirm that 1) we are actually part of a city sewer system, 2) when we were hooked up, 3) what affect Hurricane Sandy had on that system, and 4) if it is possible to get a water dept inspection of our sewer connection to make sure the blockage is in fact within the confines of the property and not a township problem causing a back flush of some sort into our drain system. In the interim, can anyone give us some guidance as to what this tank(box) in our basement that seems to be a final component before waste water leaves our property to empty into the city sewer system is and what we can do to get the problem cleared out? Thank you so much for taking the time to read this lengthy dissertation!

I'd have a professional plumber come out with a camera to run through your sewer drain out to the street and confirm you don't have any collapsed or settled terra cotta pipes between the street and your house.

If there are low spots from settling you will see it as those are prone to clogs there as waste settles.. or if you have tree roots or pipe that's broken and crumbling.

And this is one of those cases a picture beign woth a thousand words... and a video being worth far more than that.

Then you have a better idea what you are fighting. Or at least know what you don't need to worry about.