OK, can someone explain what is going on here? I am not a professional plumber, but I've done my share of plumbing, and I have no explanation for what I see here. This is the plumbing for the shower in a friend's new addition.
Note the shower: orange shower control, hot red Pex line coming in from the left, white cold pex line coming in from the right, then white Pex line going vertically to feed the shower head, steel shower pipe coming out from the wall, all to be expected ... except wait, what the fluff is that T in the Pex line feeding the shower head, about 6" from the top? It leads off to a 3/8" copper pipe, which is carefully threaded through the studs, to be changed back to 1/2" Pex. This Pex then T's off to a horizontal 1/2" white Pex line, that then turns again 90 degrees at both ends towards the floor. Both sides of this Pex line then disappear into the ground beside the main standpipe. So WTF???? So each time she takes a shower, water is being fed into the ground, into the foundation? I live in Ontario, so the ground freezes, though this is a basement with floor well below the frost line. But what is the purpose of this getup? I am at a loss.

It is possible it feeds back into the main drainage. But I question WHY this was done? And it would have to feed in BEFORE some trap to prevent sewer gas coming back in through the shower head. What in heck could this be for???




If you look in this second image, against the far wall you can see the two white Pex pipes coming down vertically off the ends of the horizontal white Pex pipe segment, and then both pipes go into the ground beside the stand-pipe.





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is it going back to the water heater?

No, it's going into the ground. You can see it in the photo: the two white pipes poking down through the concrete floor beside the stand pipe. And besides, that would be incredibly dangerous for bacterial contamination of the hot water. And furthermore, without a tap, you'd have a constant shower. So no, that's not possible.



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? the "plumber" had a nervous breakdown ?

or had mushrooms for lunch ...........................................





An enigma wrapped in a puzzle encased in an unanswerable question.

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

In addition to what Bern said.....

It looks like there is a straight stop valve installed where it branches off from the shower head riser.

Manual trap primer for 2 floor drains ?

Still does not make any sense.

@Bern: lmao. Indeed.
@Curly: Yes, trap prime/feed is the _only_ thing I could think of that is plausible. The top T is now exposed again (the shower tub was not properly sealed and the frame rotted - these photos were taken long ago during construction, so I don't actually have access to the pipes going into the ground), I will check if it is a valve. But trap priming is actually not at all reasonable:

1) There is only one trap under the concrete, the shower trap. Why split that feed into two? You sure aren't priming the toilet or sink traps!
2) To feed this "trap primer", if it is priming the shower trap, you have to turn on the shower...which primes the trap without this feed, so WTF?
3) To prime any traps anywhere, just use the plumbing? In some emergency, use a bucket? Why put plumbing in for that?

That horizontal pipe is carefully plumed: very horizontal, relatively long (12" each side?), equal lengths on both sides. Why all this architecture?

Does anybody know of any building codes anywhere that would call for such an architecture? I am in Ontario (Canada), any Ontario plumbers know if there is some bizarre building code for plumbing basement suites?

I am just at a loss.

@Curly: Good eye! I did not spot that stop valve. I have not actually gone there, just looked at the photos, and completely missed the valve. I see it now. Adds to the mystery. A stop valve buried behind a wall that cannot ever be turned on. Very very useful.

Yah, this is just fluffed. I think Bern had the correct answer.

The more I think about this, the more I am convinced Bern may be on to something: that plumbing (copper pipe, horizontal Pex) is against an outside wall, on the _cold_ side of the insulation. If it ever has water in it, it will freeze and burst. So WTF????



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I can see it going into the ground, but where is the other end of it?

I see a fairly large sized hole drilled through the stud, and three lines entering that hole. The white PEX (cold) the red PEX (hot) go in and may be turn right to go to the other side looks like a stand pipe for a washing machine? The MIXED water after the mixing valve splits off to go into the hole as well, with a restricted section of may be 3/8 copper, with a shutoff then it splits into two both going down...to the slab but they have to lead to somewhere. It looks deliberate & intentional. The fact that the shutoff is inside the wall seems to suggest it was meant to be temporary. I would find the plumber who did this and get some clarity. Very puzzling but I hope there is an explanation...do you have a radiant heat panel or floor system somewhere?

It must have been temporary - why else have a valve closed off/buried within a wall. It's like the plumber wanted to fill the floor traps without using a bucket. I think Bern's comment was on the mark...

Could they have intended to make a recirculation system for the hot water and bungled?

No. The lines go into the floor, which is a basement floor, so into the ground. If you were going to feed back to hot water, you'd go along the ceiling where the hot water feed came from.
Was almost certainly some silly method for priming traps beneath the concrete, so the guy didn't have to use a bucket when the construction took 8 months. But he should have removed it, capped it, something, not left it hooked up to the mixed shower feed.