Plumbing – UK to East European shower pipe converter

When the S-pipe is firmly threaded into place such that it will not leak then it should be able to hold up the shower head. If the shower head is not staying up in position then you do not have the S-pipe threaded in firmly enough.

I installed one of these shower S-pipes in my shower in order for an accommodate an large "rain shower" type head. I removed the original small angle pipe and then inspected how the shower head plumbing was attached up in the wall behind the drywall. This needs to be FIRMLY fastened to the studs in the wall or to a cross member that bridges between two studs. To get a idea of what the shower head plumbing pipe fixture looks here is a picture of a typical installation:

If the shower head plumbing is not securely fastened then steps need to be taken the strengthen the mounting including the possibility of adding a proper cross member between the studs. The reason for this is that hanging a heavy shower head up on a tall S-pipe will transfer a lot of torque into the plumbing line and if not properly mounted could lead to future plumbing failure and leaks.

For installing the S-pipe first make sure that the mating pipe threads in the plumbing are clean and free of any debris. Then you put Teflon plumbers tape onto the end of the S-pipe. Do not put on an excess of the taping. Finally the S-pipe can be threaded loosely into the plumbing pipe. When tightening the S-pipe no wrench is really needed for the S-pipe itself because its length makes it easy to turn it into place. An the ideal situation, if you have access to the shower head plumbing, is to use a plumbing wrench to counteract the thread-in force of the S-pipe so that the rotational torque does not get transferred into the plumbing. If this is not possible then you have to depend on the quality of the plumbing attachment to the studs or cross member in order to hold the plumbing in position during installation.

When you get the S-pipe rotated into position stop turning when it thread joint is tight. If the joint gets tight before the pipe is in the correct position then you may need to torque it into final position if the amount of turning is less than about a quarter of a turn. If more than the quarter turn it may be necessary to remove the S-pipe, re-clean the threads on both the S-pipe pipe and the plumbing pipes and start afresh with just a little more of the Teflon tape on the end of the S-pipe.

Your problem is the sewer, not the "fresh" water.

Activity on another floor is almost certainly sucking water out of the sewer trap at your laundry and/or bathroom sink. The dry trap then has no resistance to rising sewer gas. Doing laundry fills the trap back up. Here's what it might look like in the wall behind your laundry machine. For proper operation the U shaped part must be full of water at all times:

We're talking China, so shoddy design or construction are a possibility. If the sewer trap is not vented, or is S shaped rather than P shaped ,it is vulnerable to siphoning dry. See https://en.wikipedia.org/wiki/Trap_(plumbing)

Test this next time you have the smell. Slowly pour about 1 liter of fresh clean water down into the drains near the laundry, and see if the smell starts to dissipate.

You can fix this by crudely mounting a second waste trap between the washer and the building's trap. This could even include an "automatic air admittance valve" just to act as a vent without the need to penetrate the roof or reach a window.