P trap into end of waste line (now an S trap)

[PaulNY]

Sorry. I mis-read. I saw "there was definitely dirty water getting into the guest shower drain when flushing the guest toilet" and was thinking there was dirty water coming out of the guest shower drain.

ok, thanks! wanted to clarify.
The shower drain enters the waste line very close to where the guest toilet waste pipe goes into the waste line.
As Terry pointed out, the cause would appear to be the tee from the guest toilet being a santee and not a wye, so waste could flow in both directions on the horizontal.

The S trap that is now in place on the shower drain instead of the P trap (will post a pic later tonight) may indeed "work" and not be an issue, but it's not code (which I definitely want everything to be within code even if I never plan to sell the house).
This guest shower may go unused for a couple of weeks so even a little syphoning coupled with some evaporation might cause a break in the water seal (not certain about this, just thinking logically out loud).
I'm going to get a licensed plumber in to evaluate everything and go from there with a course of action.

Thanks again!

 

[PaulNY]

Again, really appreciate everyone sharing their knowledge and insight!

Here is a picture of the S trap on the guest shower drain that replaced the previous P trap.

 

[Sponsor]

 

[Terry]

Here is a picture of the S trap on the guest shower drain that replaced the previous P trap.

Wow! He's trying, but doesn't understand how it needs to happen.
After the trap, the trap arm can grade downward at a 2% slope. He made that an S trap that will siphon. That needs to come out. What does this guy do for a living? Someone needs to make him stop working with plumbing. If he's been doing this a long time, I can't even imagine the harm he's done. All those homes with weird smells now.

 

[PaulNY]

Wow! He's trying, but doesn't understand how it needs to happen.
After the trap, the trap arm can grade downward at a 2% slope. He made that an S trap that will siphon. That needs to come out. What does this guy do for a living? Someone needs to make him stop working with plumbing. If he's been doing this a long time, I can't even imagine the harm he's done. All those homes with weird smells now.

Thanks Terry, he is a contractor for a living. I messaged him and said I see you put in an S trap instead of the solutions we discussed, is that within code?.. (already knowing it is not within code). He replied "Yeah, should be fine" I told him I was concerned about siphoning and was going to get a licensed plumber to take a look and get a recommendation. He said no problem but his rational was that "if it were a tub maybe could siphon. 2" on a shower was probably good"... "probably good" not confidence inspiring when I am paying for "completely correct".

Would you run the shower drain parallel to the waste line, add an aav if other venting is not possible, and drop it in to the main waste line further down?

 

[Terry]

Would you run the shower drain parallel to the waste line, add an AAV if other venting is not possible, and drop it in to the main waste line further down?

Can you draw the layout that is there now?
The guy you have is mixing pipes, using the wrong fittings, using the wrong couplings, using the wrong configurations.
He should stop plumbing.

 

[CountryBumkin]

I still don't see an "S" trap in any of the pictures. What am I missing?
I'm not a pro.

 

[Terry]

S Trap
He should have come straight off the 2" and added the trap, not adding a bend upward.
Fail.

It should be like this.

With AAV's. Those are lav fittings. For tubs I use a solvent weld (glued) trap and fittings.

 

[Reach4]

I think this is how you would draw the S.

 

[hj]

That is NOT the trap you show in a previous picture. That one is a "P" trap with a sanitary tee adjacent to it with something that looks like an AAV on top of the tee, the line continues to a 45 that drops down into a Y. Where did THAT photo come from? This photo shows a completely wrong "S" trap and would only have been installed by someone completely incompetent to do plumbing.

 

[Jadnashua]

FWIW, when you make a pvc pipe connection, the cement literally melts the plastic and fuses the pipe to the fitting...ABS and PVC plastics don't really melt together well to make a proper joint. I'm not sure the transition cement is legal everywhere. There are approved other ways to do it, but the couplers cost more and a wipe of cement.