How to get the right slope on a garbage disposal pipe
Garbage disposal outlets often make it difficult to achieve the proper downward slope or align correctly with the wall outlet. This leaves people uncertain whether the math for a required 1/4-inch per foot drop will work, how deep the connection point actually is, or how to figure out local code without paying for professional scoping.
What people tried
Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.
- 1Cutting a sanitary tee into the existing stand pipe or back wall pipe
- 2Using 45-degree fittings or street 90s to route the plumbing
- 3Opening up the cabinet to tie into the main drain
- 4Paying a plumbing company to scope the existing line accurately to determine its depth
- 5Asking the city planning department over the counter before submitting plans
- 6Risking a 1/8" slope and hoping the inspector approves it
In their words
Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.
“I just don't know how deep that point is. I found a plumbing company that says they can scope it accurately to determine depth, but of course they don't work for free, nor should they.”source ↗
“If I need a slope of 1/4" per foot, it is uncertain right now whether the math will work”source ↗
“Minimum slope of 1/4" or 1/8": is this something that the planning department (they're the ones in my city who approve plans and issue permits) can tell me over the counter before I submit plans? Or am I not even looking at the issue the right way?”source ↗
Where this came up
People with this problem also raised
- 2How to route a plumbing vent offset around obstacles
- 3Why does the drain snake keep coming out the other drain?
- 4How to maintain an outdoor sump pump discharge pipe in the yard
- 4How to bury downspouts in a flat yard with no slope
- 2What size pipe do I need when combining two 3-inch pipes?
- 2What to do with a water line under a walkway?