Construction
Drain Pipe Slope Calculator
Code minimum is 1/4" per foot for 2" and smaller, 1/8" per foot for 3" and larger. Too steep is bad too (solids leave water behind).
Total fall (in)
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- Min slope (in/ft)
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- Total fall (ft)
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- Max slope (in/ft)
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FAQ
Can it be steeper than 1/2" per foot? +
Generally no — water races ahead of solids, which then dry and clog. Stay between min slope and 1/2"/ft.
Code reference? +
IPC 704.1 / UPC 708.0. Always verify with your AHJ for jurisdiction specifics.