Main line issues, but no root cause? voodoo perhaps? need some wisdom

[John F]

I've had to clear a clog in my main line four or five times in the past two months.

I've run a 50ft snake up and down the line.
I've bought a 50ft power unit (this one) and ran it down the line.

I now fear that the actual setup is improper.

The issue happens where 3 rooms connect to the main line
1) my master bedroom
2) guest room
3) sons room (just his toilet, his sink is further down)

After this last clean out I tried to figure out if it was insufficient slope, or a belly, or something else, and what I saw really confused me. (See pictures for the clean out I observe from)

Once the clog is cleaned, and things are open, I can run a ton of water from the guest room down the pipe..
I had my wife run the tub, sink and flush the toilet, and dump a 3 gallon pail in the toilet all at once
the water ran great down the pipe.
The flow was strong and never looked odd.

But when she went to the master bedroom and flushed the toilet, as soon as it hit the main pipe the water backed up... and the flow seemed to stall out and it slowly (very slowly) drained away without any visible current.

As far as I can tell there are no obstructions..

Hope someone here with some experience can help me out.

Please ask any questions, I wasn't sure what past this would be more information or just more noise.

Here is the setup:

1

• John F
• Jan 6, 2020

2

• John F
• Jan 6, 2020

3

• John F
• Jan 6, 2020

4

• John F
• Jan 6, 2020

5

• John F
• Jan 6, 2020

6

• John F
• Jan 6, 2020

7

• John F
• Jan 6, 2020

Plumb

• John F
• Jan 4, 2020

home

 

[Jeff Handy]

Maybe it’s just the camera angle, but in pic #5 the area with excess purple primer, left of center, looks like the start of a belly.

It looks as though the drain is going uphill to the right, after that point.

Measure down from the joists, assuming they have not sagged.

Or just hold a four foot level under the drain line.
It looks like by the word PROBLEM the drain is level, not pitched down.
And by AREA, it is running uphill.

 

[John F]

I'll go measure it, my fear is that you're right, and I have to work backwards raising the slope of the pipe from there all the way back under the master.

 

[Jeff Handy]

In the meantime. after you clean the line again, flush the toilets at least one extra time, after a poop.

It helps to move the solid loads along, down the line.

Modern toilets don’t put much water down the drain, not like the old days.

Otherwise, you have three lines all dumping their loads together at what looks like a low spot.
So they are probably forming log jams there.