It is correct that if you hear gurgling in the shower drain when flushing a toilet, then the trap is being siphoned out. Sewer gases are dangerous. I'll guess you are in a state that doesn't have the strictest plumbing requirements, that you called in repair plumbers and not Master plumbers, or that Master plumbers in your state are not highly qualified. Get this DWV done right. It is more complex than replacing the wrong fittings. Someone with a strong ability to visualize in 3D and express it in writing might be able to explain a solution to you, but this won't matter once you get a Master plumber in there to re-route the pipes. It will look a lot more elegant. There are a number of new geometries he might consider, based on the joists and other mechanical obstacles.)

hth

There is more to a venting system than simply open pipes.

If it was not designed and installed correctly from the start you can have siphoning.

If you have had 2 plumbers look at it,,i wonder why they didn't comment on the major code violations???

Thanks for the replies. So what exactly are the code violations that you're seeing? Do you see something clearly done wrong here?

I don't have any issues with hiring someone to redo the whole works. Thus far though, I haven't had anyone look at it and suggest something was wrong with the way it was done.

Boy, that's some hoakie looking plumbing. The 2 plumbers that you had look at it probably ran out of there because that's going to be a lot of work to try and make that to code. The vent for the toilet should tee in after the toilet bend. If I'm looking at it correctly, is that line coming from the kitchen sink DRAINING THROUGH a tee from the tub AND THEN going through the trap from the tub?? Is there a vent on the kitchen?----The Captain

1. From the base of the VTR (Vent to Roof) to the Wye at the closet bend you have a horizontal dry vent. CODE Prohibits any horizontal dry vent offset until the vent reaches an elevation at least 6" higher than the flood level rim of the highest fixture served by that vent.

2. The Trap on the 2" from tub is constructed with 1/4 bends and a return bend thus the water level in the trap exceeds the maximum allowable depth. (Code requires using Street 1/4bends & Return Bend to make a trap.)

3. It appears as if the line from the kitchen sink is tied in upstream from the trap in the picture. If so and if there is a trap at the kitchen sink location, you then have two traps in series, which is code prohibited. If there is no trap at the kitchen sink you then have two unlike fixtures sharing a common trap, also code prohibited.

4. The tub drain line is connected to the main drain by means of a horizontal Sani-Tee which is prohibited. Code requires a Wye & 1/8 bend.

Need I go on????

Yes, the kitchen drain does in fact go through the bathtub trap.

As best I can tell, there's not a separate vent for the kitchen, but I'm not 100% certain on that.

@ lazypup: Thanks, that's exactly what I was asking for.

So, is there a simple fix that would be worth trying to remedy the issue, or does the whole thing simply need to be redone?

Since it's all made with plastic, the simple fix is to cut out the plastic. Redoing it all is easy for someone 1/ on site, who 2/ is a Master plumber.

It would have to be all cut out and repiped, but it may be a challenge to vent the kitchen sink and the tub if there isn't one there already. May have to open some wall. And to keep the closet bend up in the joist space, if it is desired, and still have it vented properly...