A few years back, when building our house, we asked the plumber to rough in a sink drain in the basement for a future wet bar. Now I am doing the wet bar and noticed that there are two 1-1/2" pipes coming out of the slab, about two feet apart. I assume that one is a drain and one is a vent, but since they are not marked such, I cannot determine which is which. The only difference that I can tell is how the plumber capped them. One has a normal glued on cap, the other has what I believe to be a dishwasher fitting (see picture) and coupling that were fit without glue. Since I have lost track of the plumber, my hope is that this is some standard way of identifying the vent. Short of this, is there some other way of telling which is drain and which is vent? If not, how do you suggest I proceed?
Thanks in advance,
Thanks in advance,