slope for plastice drain pipe Home › Forums › Archives › Old Bulletin Board Archives › slope for plastice drain pipe This topic has 0 replies, 1 voice, and was last updated 22 years ago by jobehr. Viewing 0 reply threads Author Posts 24 Feb 1999 at 10:53 am #280621 jobehr adding toilet and shower to basement. using 3 plastic pipe connecting to existing 3 iron pipe. need to know how much slope per foot i should have. maximum distance about 8. Author Posts Viewing 0 reply threads The forum ‘Old Bulletin Board Archives’ is closed to new topics and replies.