Stinky Shower Dilemma

[Robert Biggins]

Greetings BP Family, I hope all is well for everyone!

So, with the current home that I reside in, my plan is to transfer it to a rental property since I will be relocating to a different state for work related purposes.  The home itself is in great condition.  However, there is one annoying problem with the master shower; it reeks a stinky sewer smell after taking a nice hot shower.  We purchased the home in 2017 and everything was fine.  No smell whatsoever.  Just recently within the past few months this year (2020) we noticed a weird odor, not knowing where it came from at first.  Suddenly we realized it was the from the shower drain.  

A total of four plumbers looked at the situation and provided their recommendations.  The first suggestion was to demolish and rebuild the shower pan and plumbing system, presuming that the p-trap was not properly built to prevent the smell from rising up through the shower drain.  One of the plumbers suggested a shower pan test, and it passed.  A different plumber actually utilized a snake camera to visually check the alignment of the drain system and it was properly built, including the p-trap.  Using the baking soda and vinegar trick lasted for a brief time frame but then the foul smell reappeared.  Basically I don't want this to be a nuisance to future tenants.  We've been attempting to discover a permanent resolution.  Other than exhausting thousands of dollars to rebuild the plumbing system, would anyone have suggestions/recommendations for this situation?  Has anyone been through this plumbing ordeal before?  

[Jim K.]

@Robert Biggins

The p-trap is most likely leaking or siphoning. From your description, it sounds like this shower is built with concrete-embedded piping on a slab (nobody's opened this up from the bottom to look at it). The p-trap may have a hole or crack in it, allowing the small amount of water that's in it to drain out slowly. Sewer gas can then come up out of the drainpipe. Alternatively, there may be a situation is which the water is pulled out of the p-trap too quickly, siphoned out by inadequate venting or movement in the drainpipe, or some kind of blockage, or, or, or.

Please don't tell me that not one of your four plumbers suggested this possibility. I suspect this is exactly what your first guy said, and he was right about the expensive rehab necessary to deal with it.