Hi all. I have a question about the need for a p trap. A plumber put in my washer dryer lines and connected drain. See first pic, there is nothing else to the left of the washer dryer line, it's all drain outside the house from there. At first he didn't have a p trap in there at all but a friend mentioned something about it so he added one under the WD box.
I'm wondering, if p trap is supposed to stop sewer gasses, what is stopping those gasses from passing over to my dishwasher and sink that is on nearby wall connected to same drain? Do I need another p trap? Or should p trap be to the left of the WD to stop gases for the whole drain line instead of just the WD part.
I'm wondering, if p trap is supposed to stop sewer gasses, what is stopping those gasses from passing over to my dishwasher and sink that is on nearby wall connected to same drain? Do I need another p trap? Or should p trap be to the left of the WD to stop gases for the whole drain line instead of just the WD part.