drain line slope Home › Forums › Public Forums › Drainage & Sewerage › drain line slope This topic has 1 reply, 2 voices, and was last updated 24 years, 6 months ago by hj. Viewing 1 reply thread Author Posts 21 Feb 2000 at 12:03 am #278448 MasterPlumbersKeymaster What should be the correct slope of the kitchen drain line? Pipe comes through the floor to basement and runs 24 feet to corner and turns 90 degrees and runs 10′ to vertical pipe up from basement floor. All pipe is 1 1/2″ PVC. 21 Feb 2000 at 3:24 pm #298538 hjParticipant About ten inches, but 1 1/2″ pipe is really too small for a sink drain that is that long. Author Posts Viewing 1 reply thread You must be logged in to reply to this topic. Log In Username: Password: Keep me signed in Log In