Sump pit size

[Sifu]

I am being told that sump pit size from IPC 712.3.2 (2018) applies to all sumps...such as manufactured units like a Zoeller 105 under sink kits. I disagree, and believe they are for field constructed, dug out pits. Applying those size requirements would eliminate the kits used under sinks and lavatories. Thoughts?

 

[Paul Sweet]

IPC 712.1 says that sumps are required for "building subdrains that cannot be discharged to the sewer by gravity flow." This implies multiple fixtures and probably water closets.

IPC 712.3.2 allows smaller sumps if "otherwise approved". I don't see why the Zoeller 105 wouldn't be approved for a single sink unless the inspector is being being a real jerk.

 

[Sifu]

This is an existing building undergoing a minor remodel so I think it is OK on flow requirement. I have been asked my opinion by another reviewer because the inspectors boss is claiming it should not have been accepted in plan review. I have never required those sump dimensions for these under-counter pump & basin kits, and truly believe if I did that same person would let me know how ridiculous it is to do so. But as plumbing is my weakest link, I am interested in other opinions.