Seems like it would back up in the toilet before the sink drain. I know that if my bath grey water fills, it backs up in the lowest drain which is the shower stall, not the sink. The post seems to say that it doesn't?
2011 351RLTS Eagle, Mor/Ryde suspension & pin box
06 F350 Lariat PSD, SRW, LB, CC, EGR delete kit, 16K DrawTite hitch, Timbrens, TST TPMS
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