The shower cabin in my apartment has a drain manufactured by Geberit: there's a wide, but very tiny alcove (covered by a decorative plate on the photo) hosting a floor-even vertical collector pipe.

As of late, poor drainage flow is a huge issue, and none of the traditional cleaning procedures known to me work properly:

  • Taking out the comb insert and rinsing it only removes the outermost layer of filth
  • Pouring some amount of drain cleaner in and leaving it overnight doesn't work as well as it used to
  • Flexible spring cables and spiky plastic sticks designed to capture and pull dirt out of the pipe only go a few centimeters in, probably due to the pipe's complex shape
  • Plungers can't fit in, since the entrance is about 4-5 cm high (not enough vertical space inside either required for proper plunging). Same goes with plumbing "guns" that compress and then release air: while some have straight angle joints, these are still too large to get inside.

Are there any other options, other than resorting to calling a plumber?

In my mind, the ideal tool would be a tiny flexible plunger (cup height <= 4 cm, diameter ~= 5-7 cm) powerful enough to generate good suction, but flexible enough to be turned sideways — if those exist at all, what are they called?


  • 1
    Is poor drainage still a problem with the "comb insert" completely removed?
    – brhans
    Feb 7 at 10:41
  • @brhans yes, it's the same, and the comb is pretty generous and obstacle-free anyway. Feb 7 at 10:46
  • Is this a rental apartment? Feb 7 at 11:52
  • 2
    If it's a rental, contact the landlord to have him call in a professional plumber. Should be on his dime in most jurisdictions...
    – FreeMan
    Feb 7 at 12:36
  • 1
    I found a reverse image 5th in the top image carousel at stylepark.com/en/geberit/floor-even-shower-drainage. I can't tell if the p-trap area is flexible and all bunched up maybe for shipping versus shaped unconventionally.
    – popham
    Feb 7 at 16:07

3 Answers 3


Use a large plunger. Rather than centering the plunger over the drain, sneak its side in there over the drain. The shower floor will seal the rest of the air chamber. Depending on the shape of the plunger, you might have to half compress it to get it in there, but it will spring back to give you a workable air chamber.

An accordion plunger with a wide base could probably work similarly. The wall would collapse the side of the accordion quite a bit, but you would still have a workable air bladder. It might take a second person to keep the thing well seated, though.

  • I considered doing this (with a regular plunger), but there's approximately a 1 cm drop, which prevents any tight contact: i.imgur.com/V71FCb1.png (excuse the crude drawing). However now that I think of it, it might be possible to cut out a similar "step" out of a plunger's cup and hope that remaining rubber, when pressed tightly, will seal the gaps. Feb 7 at 22:28
  • 1
    @a small orange, or you could cut a hole in a piece of plywood (or something) to level it out again. Something like duct seal compound could work for getting close to air tightness.
    – popham
    Feb 8 at 0:02

Answering my own question: what helped this time was a whole litre of Tandil gel made of sodium hypochlorite (bleach) and sodium hydroxide (caustic soda), left overnight and rinsed with hot water.

If that doesn't work next time, I'll turn to an accordion plunger with an extra board for levelling the drop, as pointed out by @popham.


That is a Gerberit Duofix Wall Drain for Showers. Like the more common Duofix in-wall toilet, it should be, but almost never is, installed with an access panel. In the case of a shower the panel would have to be on the back of the wall in the next room. Have you looked there?

If you look at the design of the thing, there is no way to snake it. If you are rough with a metal snake you will probably damage it.

You should call Gerberit technical support. Ask them what their thinking was for maintenance.

What will a plumber do if there is no access panel? A plumber will either use chemical drain cleaner or will smash open the wall and rebuild the shower.

Buy some goggles and gloves and the most powerful chemical drain cleaner you are willing to work with, and follow the directions including all the wait time required.

Another possibility: Build, make, or 3D-print an adapter for a plunger or wet-vac. Go to a big hardware store, look at all the 90-degree plumbing fittings, 90-degree vacuum-cleaner attachments, and so on ... find something that will fit inside the wall opening and seal nicely to the drain. At the open end make something (it can just be duct tape?) to connect it to a plunger or a wet vac that you can try in both directions or even to a garden hose.

  • Unfortunately, there is no "next room" in my apartment, and most likely no maintenance panel exists, too (unless it's in an adjacent section of the building). Regarding the hardware store trip idea, yes, I considered making an "extension" of the drain pipe, but 1) thought I'd have reinvented the wheel, and 2) it's still one of these last resort measures you expore if you're absolutely out of quick and/or traditional options. Regardless, a very nice and complete answer, thank you! Feb 8 at 19:29
  • Also, another thing I imagined is that plumbers might have special tools for this exact task (such as wet vacuums or "special" plungers) unknown to me, which I, too, could wield. According to your answer, it seems that no, not really. Feb 8 at 19:33
  • A garden hose is not typically used for sinks, toilets, etc because of the potential to flood the bathroom. And for showers, a short plastic snake and some chemicals are usually very effective. In your case, the circumstances are different: you can't snake it, chemicals have not been effective, and there's no harm in flooding the area. So think about how to make that work.
    – jay613
    Feb 8 at 21:06

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