If reventing is complicated and wet venting isn't allowed, installing a loop vent is an ideal alternative. An example would ...

An island sink presents a unique plumbing problem ... s overflow level before it goes horizontal. Obviously, a vent pipe in a kitchen island can’t do that. One solution to this quandary is ...

When that line becomes obstructed or improperly vented, wastewater can flow back into the sink instead of draining away as intend ...