OK, I'm not sure how to explain this best... If you have a better wording in mind for the title, please edit or tell me:

The setup: I live in an apartment. The bathtub after the U-bend connects to pipe 50mm in diameter. That pipe then connects to a larger pipe (100 or 150, not sure) which then connects to the vertical sewer pipe. The 50mm pipe is straight and about 1m long - but it passes through a wall so I can't remove it. The bathtub connects to the 50mm pipe via a 45 degree junction and the 50mm also continues on in the other direction towards the kitchen.

So.... in Ascii art...

                                        Neighbors above
Kitchen       Bathtub                          #
   |             |      1m        Fat pipe     #
                45°                            #
                                        Neighbors below

The problem: I can clean the U-bend easily enough, but the straight 50mm pipe is another story. Over time it clogs and the bathtub starts draining slowly. With great difficulty I can get disassemble the connection to the kitchen and remove the 45° junction and poke around with a long stick which helps... for a while... but it's a pain to do so. I could however easily access the 45° junction and put a drain snake it (well, if I had one).

What fills me with doubt is that everything I read about drain snakes suggest that they are for removing acute blockage - something big suddenly stuck in the pipe. You can dislodge that and everything is fine. In my case however it's a slow buildup of gunk over years of time. The pipe doesn't block, it's more like it's inner diameter slowly shrinks... And I doubt if gettin a drain snake would help here. If there was something like a 50mm round brush, then maybe... but I can't find any.

Am I overthinking it and a drain snake is exactly the tool for the job, or is there something more specific for this scenario?

  • Look under chimney and/or tube brush, amazon has quite a few. Will be messy when you pull it back out. Will need handles/poles also. Seems like main problem is not enough slope to drain completely, but that just be picture. – crip659 Mar 7 at 15:45
  • @crip659 - The slope is... ugh.. let's not go there. But, yes, you're essentially right. – Vilx- Mar 7 at 17:10
  • @crip659 - I've seen those chimney brushes, but I was wondering if they weren't too hard/rough for PVC sewage pipes. – Vilx- Mar 7 at 17:37
  • @Vilx- if you do own this mess maybe you should consider replacing it with something better. How do you know so much about the pipes? You say "it goes through a wall" ... are these pipes all surface-mounted on walls except where one goes through a wall? If so, replacing them with a better arrangement is relatively easy. Run the fatter pipe as close as you can to the bath and then run a vent upwards from there and parallel to the drain to join the main stack a foot or so higher. – jay613 Mar 7 at 17:37
  • @jay613 - I do own it, and I have replaced most of the pipes myself at some point, so I know them well. Replacing them ALL however would be a significant project at this point. We had some renovations a few years back and the fat pipe (and its joint with the thin pipe) are now rather difficult to access. It can be done, but I'd need to remove the entire toilet seat (forgot to draw that in the picture), and... not easy. Also, what would I gain? Fatter pipes? I don't see anything that I could substantially improve. – Vilx- Mar 7 at 17:43

A. Chemical drain cleaner ought to do a reasonable job in this situation

B. Yes there are snakes with attachments like you suggest

C. If you are renting perhaps the inaccessible part of the plumbing is the owner's responsibility. Without getting into a big discussion about legalities wherever you are, you could ask nicely.

D. Usually a frequently blocking bath drain is caused by someone with long hair who uses too much conditioner. Get a good hair screen for your tub drain and instruct any such user to clean it during and after each use and to go easier on Hair products. Require each such user to participate in the disgusting business of clearing the drain.

E. A common horizontal pipe shared with the kitchen is a whole other level of problems. I've never seen that before. The combination of cooking fats etc plus hair is formidable. Assuming you don't own this mess and can't improve it, you may want to create some kind of Easy Access to do cle an outs.

  • I would think that the combo drain could cause backup into the kitchen when the drain was slow and the shower was in use. If they are really on the same drain line the drain cleaner should be added in the kitchen I would think. – Willk Mar 7 at 16:06
  • A - Haven't tried that yet. How do I keep it from just flushing through? C - Nope, we own the apartment. D - I'd prefer not to sleep on the couch. E - tiny Soviet-era apartments. You wouldn't believe the amount of crazy in them. But on the bright side - there's not much pipe to take care overall. – Vilx- Mar 7 at 17:13
  • A brush should do, but remember when you pull it back out, it is like a hundred tiny slingshots loaded with crud. Brush should be slightly bigger than pipe in diameter, it flexes. – crip659 Mar 7 at 17:27
  • @Vilx- A - there are some products like gel ones or "main drain cleaner" that address this problem. Get local advice about local plumbing and locally available products and read the label carefully, these things are dangerous. D -- Why would even THINK for one second that I was referring to her? :-D – jay613 Mar 7 at 17:28
  • @Willk we can only guess but maybe the height of the kitchen trap above the horizontal pipe, combined with low flow of water from the tap, prevents backup to the sink from becoming noticeable, whereas the lower pressure from the lower level bath drain and the filled up tub make the problem obvious. – jay613 Mar 7 at 17:30

This answer to illustrate the comments about how venting might be a minor factor for OP.

Here is a picture of three fixtures with added venting for the bath and sink. enter image description here

And here is the same picture where I've highlighted in red the section of pipe that is analogous to your problematic one, and in green the venting that you do not have. You could imagine the basin in this diagram to represent your kitchen. (Note in this diagram the vent is connected to the main stack incorrectly, it should not be at 90 degrees but presumably in this diagram it is the upper floor of a house with no water flowing from above).

enter image description here

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