How much should a sewr pipe slope?

Take this question to plumming, ask speedball

The usual grade is one eighth to one quarter of an inch. It depends on the diameter of the sanitary drain. The grade of the drain is determined by the journeyman Plumber. When the
Inspection is done a ball test is performed to ensure there is a proper grade.

The usual slope is 1/4" to the foot in drainage 3" or less and 1/8" in pipes 4" or larger.
THe night before inspection we block the sewer off and fill our stacks to overflowing from the roof. Next morning the inspector checks for leaks and lets the water drain. If no leaks and the water drains OK we have passed inspection and can proceed to the next phase which is trim out and final inspection. Did this answer your question? REgards, Tom