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New to the forum although I use it frequently for reference. I'm running fixture drains from a bathroom to the main drain stack (about 2 ft to the right of the end of the pic.). My question is about the p trap shown. I have a 2" vertical drain from a shower pan, p-trap, 2" vent then it connects to 3" horizontal drain via a combination wye. Upstream I have waste from vented vanity and vented toilet. Is it permissable to have the bottom of the p trap below the height of the horizontal drain? (Or does the p trap need raised and tied into "2 inch vent/drain via sanitary tee with 2" waste then dropping into 3" horizontal waste line?) I am subject to 2015 IRC. Thanks for the help.