View Full Version : P trap not into wall?

06-15-2005, 10:07 PM
I am putting in a new sink base cabinet and dispoal. My problem is I cant go into the wall behind the cabinet for various reasons. The current old plumbing is an s trap that drops directly down through the floor of the sink base cabinet into the basement and then to the stack. No vent... it looks like it is a wet vent (only 22" horizontal travel to stack) I have heard that S traps are illegal. If I were to connect a P trap to the disposal is there anything that says it has to go directly to the back of the cabinet wall? What I am thinking about is taking the standard configuration, but "turning it sideways" 90 degrees so it travels to the left of the disposal and then drops down through the bottom of the cabinet and into the basement. If you were to be looking the sink from the front of the cabinet, it would look like a section view of a typical sink plumbing diagram. I hope this explanation is not too confusing. If anyone has any solutions on how to drop a drain line properly inside a cabinet I would love to hear it. Thankssink

06-16-2005, 07:48 AM
It doesn't matter how many turns it makes. If it does not have a vent going upward it is an "S" trap and it will siphon everytime you use the sink, and especially if you have a disposer. As a last resort, and it is not the ideal option, you can install a tee where the ell is and connect an air admittance valve to a riser from the top of the tee.