Sewer Smell in Shower Drain

[robert ramsperger]

New member here looking for some advice on a sewer smell problem in downstairs shower. I have searched
the site for a solution but have not come up with anything that helps. Great site though, lots of useful knowledge.

We had a plumber install a shower drain next to toilet drain under slab on first floor. I built a bathroom with a custom shower over that work and began to use it recently and discovered a foul smell in the air coming from the shower drain. The smell goes away when shower is used however when the other connecting drains are used the smell comes back. I took the toilet off to watch the flow and the other drains go back to the shower trap first then eventually find their way back out the main. Every thing drains well and the trap stays full but
it always seems to be fouled with sewer water until the shower is used. One other thing, when I pulled the toilet there is standing water in the main under the toilet. My first thoughts are to run a high pressure clean out
down the main from the toilet flange because the main might be partially blocked further down the line, hence the standing water. My other thoughts are to dig and I'm hoping to avoid that. Any comments welcome. thank you. Pictures attached.

 

[Terry]

I'm not a fan of a santee on it's back to pick up the toilet. Poop will splat down and go two directions. I don't know a good way of saying that.

 

[Sponsor]

 

[robert ramsperger]

I'm not a fan of a santee on it's back to pick up the toilet. Poop will splat down and go two directions. I don't know a good way of saying that.

I know I am concerned about that too. Funny thing is we are not using the toilet until we figure out what is going on and we are still getting foul
water in the shower trap. I did a test last week- I wet vac the drain and the trap stayed dry until the other drains were used. The shower drain filled immediately and then found its way out down the main. Flow rate of drains did not matter- its like the trap is downhill from the toilet flange. I wish we would have isolated the shower drain somehow, the plumber who did the work is a good plumber. If we have to dig I might suggest cutting the shower drain behind the flange and going to the washer drain. Thanks for your input Terry. Here is a pic of whats on top.
Bob