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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?

Vilx-
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  • 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 07 '21 at 15:45
  • @crip659 - The slope is... ugh.. let's not go there. But, yes, you're essentially right. – Vilx- Mar 07 '21 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 07 '21 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 07 '21 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 07 '21 at 17:43
  • @Vilx- the thinner pipe labeled "1m" in your drawing might be the problem. Simply replacing it with an identical pipe might help, as there might be hardened buildup that no snake can remove. Replacing it with a bigger pipe like the one it connects to will make the problem less likely to occur and adding a vent might (I'm not sure) help improve flow. – jay613 Mar 07 '21 at 17:46
  • @jay613 - A vent? Could you explain more about that? Also - I cannot touch the vertical pipe. And the fat horizontal one is... old. I'm not even sure what it's made of. Some sort of ceramic, I think. I've heard of plumbers breaking them by accident when trying to remove an old Soviet toilet seat. Anyways, the current toilet seat is attached to it via a flexible PVC pipe and some rubber seals, but the horizontal thin pipe is... I don't know how it's attached. Honestly, I'm afraid to touch it. – Vilx- Mar 07 '21 at 17:51
  • @jay613 I could go in to way too much detail about the whole setup, but I don't know if there is a point. Maybe you can tell me what would a proper setup would look like? I know the pipes should have a bit of a slope (which they don't), but the concept of a vent is new to me and there might be some more tricks that I don't know about. – Vilx- Mar 07 '21 at 17:53
  • Some brushes are made with stiff plastic instead of metal wires. Chimney just one name, tube might find softer ones. Even a good size round hair brush would do, if you can attach a longer flexible handle/pipe to it. – crip659 Mar 07 '21 at 18:33
  • A hair brush!! We've already established OP does not want to sleep on the sofa so he hopefully would go buy a hairbrush for this purpose :) – jay613 Mar 07 '21 at 19:09
  • I'm not SURE a vent well help here, but you have a pretty long horizontal run shared by multiple fixtures, it's possible that the horizontal pipe is not adequately vented. That means that as water runs through it, there is no easy way for air to enter and replace the water. I won't try to explain the concept here as you can go read about it elsewhere and I don't think it's your primary problem. Just a suggestion that if you DO bite off replacing this pipework with something better, you should consider venting. – jay613 Mar 07 '21 at 19:14
  • @jay613 - I've been wondering if it's possible for air to become trapped inside the horizontal pipe and thus reduce it's capacity to carry water. Is that a thing? – Vilx- Mar 07 '21 at 20:40
  • It is a thing! It's one kind of problem in pressurized pipes where air trapped in high points can reduce carrying capacity. In unpressurized drains the most common problem that arises is siphoning of traps by the drain water. The flow creates negative pressure that pulls the water out of the traps and lets stink enter your space. Reduced flow is not the primary problem but it could be a factor. The solution is 1) NOT arranging pipes the way they are in your diagram and 2) allowing air to enter at appropriate places. – jay613 Mar 07 '21 at 20:46
  • I've added a picture in a new answer to help illustrate how venting might help your plumbing (but again, is probably not the primary problem you have right now). – jay613 Mar 07 '21 at 20:53
  • @jay613 - Well... I've never had a trap siphoned, so I think that is definitely not an issue. And I do believe that the top of the vertical drain pipe is open to the outside, so there should be no negative pressure there... Uff... this has actually gotten pretty much off topic, but I am very intrigued by all of this. I feel like I need to prepare a more accurate (and complete) picture of things. I'll try to make one soon. – Vilx- Mar 07 '21 at 21:44

2 Answers2

2

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.

jay613
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  • 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 07 '21 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 07 '21 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 07 '21 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 07 '21 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 07 '21 at 17:30
  • @jay613 - Yes, yes. :) Whenever I do clean the horizontal pipe (as I said, with great difficulty poking around with a stick in it), the flow from the bathtub becomes a lot better. Still, it always feels like it could be even better. Luckily, cleaning the U-bend is enough in 99% of cases. The horizontal pipe only needs to be cleaned, like, once a year. – Vilx- Mar 07 '21 at 17:36
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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

jay613
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