I'm installing a bathroom sink with very little clearance to place the trap below the waste pipe. Will this present a problem draining water or causing gas fumes? There will also be extra bends involved. Please refer to my sketch. Thanks.

Jay

You need to drop lower before adding the trap. Get below the waste then do a trap. You have drawn an S trap that's not allowed in most places.

So, what you are saying is that it would not work to have a trap above the waste? That being the case, in my situation, my only recourse would be to raise the waste pipe inside the wall? Thanks.

Not at all, I am just saying that the P trap should terminate with ahorizontal at the same level as the pipe in the wall. Extend the vertical pipe from the sink and add your trap about 4" lower than in your drawing. You can try a S trap but they are no longer allowed in most plumbing codes fro a reason.

As I understand your question, you don't have enough room below where the waste pipe goes into the wall for a trap. Putting the trap higher and elbowing down between it and the vent in the wall, will create a long banned ''S'' trap. I see 3 solutions.

1 Chop open the wall and raise the tee for the waste line and vet.

2 Chop a hole in the bottom of the vanity to make room for the trap.

3 Install a Studor or other brand of air admittance valve.