We all know that 1/4" per foot is the minimum slope for sewer pipe with solids. My question is this: Is a drop of 1/2" per foot ok or even more or should you 90 elbo it down to continue the 1/4" drop.
Plumbing Question
Oct 22, 2009
4 Replies
12% or slightly less than 1- 1/2 " per foot is about the maximum slope permitted by most design standards.
My understanding is to not exceed the 1/4/foot. The low flush toilets just don't have the volume to clean the lines and excess pitch just tends to leave solids. You would not change grade with a 90 down, but rather, two 45's.
Uh, sure would require a lot of pipe and 45s to drain and upstairs system.
Dan, Your thinking about the low slope and moving solids in a sanitary sewer is on track, however , it's acceptable to go up to a 12% slope. If that will not accommodate the needed grade change, a vertical drop is required, such as a drop manhole or a tee/wyes with a clean out. Clean outs should be provided every 75' and at every change in direction.
Keep the world flowing ;-)
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