Plumbing clogging under slab

[Matt Foster]

I have a tough one here. Brand new house (2 bath). The plumbing repeated clogs under the slab. We had a camera inspection that shows the tolite paper is accumulting around the Y coulpling where the two toilets come together. The camera also showed that as a tolite is flushed, the water level rises around the Y to 3/4 full (3" pipe, maybe 4") then slowly drains out toward the sewer. But as it is slowly draining, sometimes the tolite paper flows back toward the other tolite that was not flushed. Basicly it is taking the path of least resistance. Then as the water level in the pipe drains (takes about 40 seconds), the tolite paper is left sitting aournd the Y. This would leave me to belive that there is a low spot in the piping that would restrict the flow of the water, but the camera inspection shows no standing water in the pipes. The plumber who plumbed the house says no standing water rules out a low spot. The camera technition also had an crude ultrasound devise that showed a low spot around the problem area, but again, we see no standing water in the system. Any ideas? could it be a venting problem (all vents appear cut off on the roof). The lady who lives there says the problem is worse when she uses washer dryer or other sinks.

[hj]

The water rising in the fitting implies a drainage problem, but without knowing more about the job, and actually seeing the tape of the video inspection, it is impossible to give a diagnosis as to what and where it is.

[Cass]

Under normal circumstances the line is snaked and clean water run through the drain to clean out everything and then the camera is run through the line. This allows you to see the problem. Is this how the work was done. There is no sense in running a camera down a line when it is clogged.

[Matt Foster]

We had the lines snaked and cleaned and then we looked at the camera. We can find nothing that would cause a blockage. But when we run the tolites, the problem area appears to fill up to the top of the pipe rather quickly and then drain down slowly. This allows the toilet paper to settle to the bottom of the Y rather than flow down the line. Over time this clogs the line. I suspect a low spot, but I would think a low spot would hold water all the time and would be visible on the camera. I also suspect a venting issue could cause air pressure in the line which would cause the line to drain to slow to get the paper down. I just hate to start jack hammering if there is another solution

[Cass]

Did they flush and watch the water flow with the camera in the line? It has to show something abnormal.

[Mikey]

What HJ said.